diff mbox series

[v5] net/vhost: support asynchronous data path

Message ID 20221024151434.1051251-1-yuanx.wang@intel.com (mailing list archive)
State New
Delegated to: Maxime Coquelin
Headers show
Series [v5] net/vhost: support asynchronous data path | expand

Checks

Context Check Description
ci/checkpatch warning coding style issues
ci/Intel-compilation success Compilation OK
ci/iol-mellanox-Performance success Performance Testing PASS
ci/iol-aarch64-unit-testing success Testing PASS
ci/iol-intel-Functional success Functional Testing PASS
ci/iol-intel-Performance success Performance Testing PASS
ci/iol-x86_64-compile-testing success Testing PASS
ci/iol-x86_64-unit-testing success Testing PASS
ci/iol-aarch64-compile-testing success Testing PASS
ci/github-robot: build success github build: passed
ci/intel-Testing success Testing PASS

Commit Message

Wang, YuanX Oct. 24, 2022, 3:14 p.m. UTC
Vhost asynchronous data-path offloads packet copy from the CPU
to the DMA engine. As a result, large packet copy can be accelerated
by the DMA engine, and vhost can free CPU cycles for higher level
functions.

In this patch, we enable asynchronous data-path for vhostpmd.
Asynchronous data path is enabled per tx/rx queue, and users need
to specify the DMA device used by the tx/rx queue. Each tx/rx queue
only supports to use one DMA device, but one DMA device can be shared
among multiple tx/rx queues of different vhost PMD ports.

Two PMD parameters are added:
- dmas:	specify the used DMA device for a tx/rx queue.
	(Default: no queues enable asynchronous data path)
- dma-ring-size: DMA ring size.
	(Default: 4096).

Here is an example:
--vdev 'eth_vhost0,iface=./s0,dmas=[txq0@0000:00.01.0;rxq0@0000:00.01.1],dma-ring-size=4096'

Signed-off-by: Jiayu Hu <jiayu.hu@intel.com>
Signed-off-by: Yuan Wang <yuanx.wang@intel.com>
Signed-off-by: Wenwu Ma <wenwux.ma@intel.com>

---
v5:
- add error log of testpmd cmd

v4:
- add txq allow_queuing check on poll completed
- unregister dma channel in destroy_device
- add dma ring size minimum limit
- fix serveral code style and logging issues

v3:
- add the API to version.map

v2:
- add missing file
- hide async_tx_poll_completed
- change default DMA ring size to 4096

---
 drivers/net/vhost/meson.build     |   1 +
 drivers/net/vhost/rte_eth_vhost.c | 512 ++++++++++++++++++++++++++++--
 drivers/net/vhost/rte_eth_vhost.h |  15 +
 drivers/net/vhost/version.map     |   7 +
 drivers/net/vhost/vhost_testpmd.c |  67 ++++
 5 files changed, 569 insertions(+), 33 deletions(-)
 create mode 100644 drivers/net/vhost/vhost_testpmd.c

Comments

Xia, Chenbo Oct. 24, 2022, 9:02 a.m. UTC | #1
Hi Yuan,

> -----Original Message-----
> From: Wang, YuanX <yuanx.wang@intel.com>
> Sent: Monday, October 24, 2022 11:15 PM
> To: Maxime Coquelin <maxime.coquelin@redhat.com>; Xia, Chenbo
> <chenbo.xia@intel.com>
> Cc: dev@dpdk.org; Hu, Jiayu <jiayu.hu@intel.com>; Jiang, Cheng1
> <cheng1.jiang@intel.com>; Ma, WenwuX <wenwux.ma@intel.com>; He, Xingguang
> <xingguang.he@intel.com>; Wang, YuanX <yuanx.wang@intel.com>
> Subject: [PATCH v5] net/vhost: support asynchronous data path
> 
> Vhost asynchronous data-path offloads packet copy from the CPU
> to the DMA engine. As a result, large packet copy can be accelerated
> by the DMA engine, and vhost can free CPU cycles for higher level
> functions.
> 
> In this patch, we enable asynchronous data-path for vhostpmd.
> Asynchronous data path is enabled per tx/rx queue, and users need
> to specify the DMA device used by the tx/rx queue. Each tx/rx queue
> only supports to use one DMA device, but one DMA device can be shared
> among multiple tx/rx queues of different vhost PMD ports.
> 
> Two PMD parameters are added:
> - dmas:	specify the used DMA device for a tx/rx queue.
> 	(Default: no queues enable asynchronous data path)
> - dma-ring-size: DMA ring size.
> 	(Default: 4096).
> 
> Here is an example:
> --vdev
> 'eth_vhost0,iface=./s0,dmas=[txq0@0000:00.01.0;rxq0@0000:00.01.1],dma-
> ring-size=4096'
> 
> Signed-off-by: Jiayu Hu <jiayu.hu@intel.com>
> Signed-off-by: Yuan Wang <yuanx.wang@intel.com>
> Signed-off-by: Wenwu Ma <wenwux.ma@intel.com>
> 

Sorry that I just realize that we need to change release notes because this
is new feature for vhost PMD. Please mention the async support and new driver
api you added.

Thanks,
Chenbo
Maxime Coquelin Oct. 24, 2022, 9:08 a.m. UTC | #2
Hi Yuan,

Please fix your system for the next times, your patch is dated several
hours in the future.

On 10/24/22 17:14, Yuan Wang wrote:
> Vhost asynchronous data-path offloads packet copy from the CPU
> to the DMA engine. As a result, large packet copy can be accelerated
> by the DMA engine, and vhost can free CPU cycles for higher level

Vhost

> functions.
> 
> In this patch, we enable asynchronous data-path for vhostpmd.
> Asynchronous data path is enabled per tx/rx queue, and users need
> to specify the DMA device used by the tx/rx queue. Each tx/rx queue
> only supports to use one DMA device, but one DMA device can be shared
> among multiple tx/rx queues of different vhost PMD ports.
> 
> Two PMD parameters are added:
> - dmas:	specify the used DMA device for a tx/rx queue.
> 	(Default: no queues enable asynchronous data path)
> - dma-ring-size: DMA ring size.
> 	(Default: 4096).
> 
> Here is an example:
> --vdev 'eth_vhost0,iface=./s0,dmas=[txq0@0000:00.01.0;rxq0@0000:00.01.1],dma-ring-size=4096'
> 
> Signed-off-by: Jiayu Hu <jiayu.hu@intel.com>
> Signed-off-by: Yuan Wang <yuanx.wang@intel.com>
> Signed-off-by: Wenwu Ma <wenwux.ma@intel.com>
> 
> ---
> v5:
> - add error log of testpmd cmd
> 
> v4:
> - add txq allow_queuing check on poll completed
> - unregister dma channel in destroy_device
> - add dma ring size minimum limit
> - fix serveral code style and logging issues
> 
> v3:
> - add the API to version.map
> 
> v2:
> - add missing file
> - hide async_tx_poll_completed
> - change default DMA ring size to 4096
> 
> ---
>   drivers/net/vhost/meson.build     |   1 +
>   drivers/net/vhost/rte_eth_vhost.c | 512 ++++++++++++++++++++++++++++--
>   drivers/net/vhost/rte_eth_vhost.h |  15 +
>   drivers/net/vhost/version.map     |   7 +
>   drivers/net/vhost/vhost_testpmd.c |  67 ++++
>   5 files changed, 569 insertions(+), 33 deletions(-)
>   create mode 100644 drivers/net/vhost/vhost_testpmd.c
> 
> diff --git a/drivers/net/vhost/meson.build b/drivers/net/vhost/meson.build
> index f481a3a4b8..22a0ab3a58 100644
> --- a/drivers/net/vhost/meson.build
> +++ b/drivers/net/vhost/meson.build
> @@ -9,4 +9,5 @@ endif
>   
>   deps += 'vhost'
>   sources = files('rte_eth_vhost.c')
> +testpmd_sources = files('vhost_testpmd.c')
>   headers = files('rte_eth_vhost.h')
> diff --git a/drivers/net/vhost/rte_eth_vhost.c b/drivers/net/vhost/rte_eth_vhost.c
> index b152279fac..80cd9c8d92 100644
> --- a/drivers/net/vhost/rte_eth_vhost.c
> +++ b/drivers/net/vhost/rte_eth_vhost.c
> @@ -7,6 +7,7 @@
>   #include <pthread.h>
>   #include <stdbool.h>
>   #include <sys/epoll.h>
> +#include <ctype.h>
>   
>   #include <rte_mbuf.h>
>   #include <ethdev_driver.h>
> @@ -18,6 +19,8 @@
>   #include <rte_kvargs.h>
>   #include <rte_vhost.h>
>   #include <rte_spinlock.h>
> +#include <rte_vhost_async.h>
> +#include <rte_dmadev.h>
>   
>   #include "rte_eth_vhost.h"
>   
> @@ -37,8 +40,15 @@ enum {VIRTIO_RXQ, VIRTIO_TXQ, VIRTIO_QNUM};
>   #define ETH_VHOST_LINEAR_BUF		"linear-buffer"
>   #define ETH_VHOST_EXT_BUF		"ext-buffer"
>   #define ETH_VHOST_LEGACY_OL_FLAGS	"legacy-ol-flags"
> +#define ETH_VHOST_DMA_ARG		"dmas"
> +#define ETH_VHOST_DMA_RING_SIZE		"dma-ring-size"
>   #define VHOST_MAX_PKT_BURST 32
>   
> +#define INVALID_DMA_ID		-1
> +#define DEFAULT_DMA_RING_SIZE	4096
> +/* Minimum package size is 64, dma ring size should be greater than 32 */
> +#define MINIMUM_DMA_RING_SIZE	64

Why? Is that related to Intel HW?

> +
>   static const char *valid_arguments[] = {
>   	ETH_VHOST_IFACE_ARG,
>   	ETH_VHOST_QUEUES_ARG,
> @@ -49,6 +59,8 @@ static const char *valid_arguments[] = {
>   	ETH_VHOST_LINEAR_BUF,
>   	ETH_VHOST_EXT_BUF,
>   	ETH_VHOST_LEGACY_OL_FLAGS,
> +	ETH_VHOST_DMA_ARG,
> +	ETH_VHOST_DMA_RING_SIZE,
>   	NULL
>   };
>   
> @@ -80,8 +92,39 @@ struct vhost_queue {
>   	struct vhost_stats stats;
>   	int intr_enable;
>   	rte_spinlock_t intr_lock;
> +
> +	/* Flag of enabling async data path */
> +	bool async_register;
> +	/* DMA device ID */
> +	int16_t dma_id;
> +	/**
> +	 * For a Rx queue, "txq" points to its peer Tx queue.
> +	 * For a Tx queue, "txq" is never used.
> +	 */
> +	struct vhost_queue *txq;
> +	/* Array to keep DMA completed packets */
> +	struct rte_mbuf *cmpl_pkts[VHOST_MAX_PKT_BURST];
>   };
>   
> +struct dma_input_info {
> +	int16_t dmas[RTE_MAX_QUEUES_PER_PORT * 2];
> +	uint16_t dma_ring_size;
> +};
> +
> +static int16_t configured_dmas[RTE_DMADEV_DEFAULT_MAX];
> +static int dma_count;
> +
> +/**
> + * By default, its Rx path to call rte_vhost_poll_enqueue_completed() for enqueue operations.
> + * However, Rx function is never been called in testpmd "txonly" mode, thus causing virtio
> + * cannot receive DMA completed packets. To make txonly mode work correctly, we provide a
> + * command in testpmd to call rte_vhost_poll_enqueue_completed() in Tx path.
> + *
> + * When set async_tx_poll_completed to true, Tx path calls rte_vhost_poll_enqueue_completed();
> + * otherwise, Rx path calls it.
> + */
> +bool async_tx_poll_completed;
> +
>   struct pmd_internal {
>   	rte_atomic32_t dev_attached;
>   	char *iface_name;
> @@ -94,6 +137,10 @@ struct pmd_internal {
>   	bool vlan_strip;
>   	bool rx_sw_csum;
>   	bool tx_sw_csum;
> +	struct {
> +		int16_t dma_id;
> +		bool async_register;
> +	} queue_dmas[RTE_MAX_QUEUES_PER_PORT * 2];
>   };
>   
>   struct internal_list {
> @@ -124,6 +171,17 @@ struct rte_vhost_vring_state {
>   
>   static struct rte_vhost_vring_state *vring_states[RTE_MAX_ETHPORTS];
>   
> +static bool
> +dma_is_configured(int16_t dma_id)
> +{
> +	int i;
> +
> +	for (i = 0; i < dma_count; i++)
> +		if (configured_dmas[i] == dma_id)
> +			return true;
> +	return false;
> +}
> +
>   static int
>   vhost_dev_xstats_reset(struct rte_eth_dev *dev)
>   {
> @@ -396,15 +454,27 @@ vhost_dev_rx_sw_csum(struct rte_mbuf *mbuf)
>   	mbuf->ol_flags |= RTE_MBUF_F_RX_L4_CKSUM_GOOD;
>   }
>   
> +static inline void
> +vhost_tx_free_completed(int vid, uint16_t virtqueue_id, int16_t dma_id,
> +		struct rte_mbuf **pkts, uint16_t count)
> +{
> +	uint16_t i, ret;
> +
> +	ret = rte_vhost_poll_enqueue_completed(vid, virtqueue_id, pkts, count, dma_id, 0);
> +	for (i = 0; likely(i < ret); i++)
> +		rte_pktmbuf_free(pkts[i]);
> +}
> +
>   static uint16_t
>   eth_vhost_rx(void *q, struct rte_mbuf **bufs, uint16_t nb_bufs)
>   {
>   	struct vhost_queue *r = q;
>   	uint16_t i, nb_rx = 0;
>   	uint16_t nb_receive = nb_bufs;
> +	uint16_t nb_pkts, num;
>   
>   	if (unlikely(rte_atomic32_read(&r->allow_queuing) == 0))
> -		return 0;
> +		goto tx_poll;
>   
>   	rte_atomic32_set(&r->while_queuing, 1);
>   
> @@ -412,19 +482,32 @@ eth_vhost_rx(void *q, struct rte_mbuf **bufs, uint16_t nb_bufs)
>   		goto out;
>   
>   	/* Dequeue packets from guest TX queue */
> -	while (nb_receive) {
> -		uint16_t nb_pkts;
> -		uint16_t num = (uint16_t)RTE_MIN(nb_receive,
> -						 VHOST_MAX_PKT_BURST);
> -
> -		nb_pkts = rte_vhost_dequeue_burst(r->vid, r->virtqueue_id,
> -						  r->mb_pool, &bufs[nb_rx],
> -						  num);
> -
> -		nb_rx += nb_pkts;
> -		nb_receive -= nb_pkts;
> -		if (nb_pkts < num)
> -			break;
> +	if (!r->async_register) {
> +		while (nb_receive) {
> +			num = (uint16_t)RTE_MIN(nb_receive, VHOST_MAX_PKT_BURST);
> +			nb_pkts = rte_vhost_dequeue_burst(r->vid, r->virtqueue_id,
> +						r->mb_pool, &bufs[nb_rx],
> +						num);
> +
> +			nb_rx += nb_pkts;
> +			nb_receive -= nb_pkts;
> +			if (nb_pkts < num)
> +				break;
> +		}
> +	} else {
> +		int nr_inflight;
> +
> +		while (nb_receive) {
> +			num = (uint16_t)RTE_MIN(nb_receive, VHOST_MAX_PKT_BURST);
> +			nb_pkts = rte_vhost_async_try_dequeue_burst(r->vid, r->virtqueue_id,
> +						r->mb_pool, &bufs[nb_rx], num, &nr_inflight,
> +						r->dma_id, 0);
> +
> +			nb_rx += nb_pkts;
> +			nb_receive -= nb_pkts;
> +			if (nb_pkts < num)
> +				break;
> +		}
>   	}
>   
>   	r->stats.pkts += nb_rx;
> @@ -445,6 +528,17 @@ eth_vhost_rx(void *q, struct rte_mbuf **bufs, uint16_t nb_bufs)
>   out:
>   	rte_atomic32_set(&r->while_queuing, 0);
>   
> +tx_poll:
> +	/**
> +	 * Poll and free completed packets for the virtqueue of Tx queue.
> +	 * Note that we access Tx queue's virtqueue, which is protected
> +	 * by vring lock.
> +	 */
> +	if (r->txq->async_register && !async_tx_poll_completed &&
> +			rte_atomic32_read(&r->txq->allow_queuing) == 1)
> +		vhost_tx_free_completed(r->vid, r->txq->virtqueue_id, r->txq->dma_id,
> +				r->cmpl_pkts, VHOST_MAX_PKT_BURST);
> +
>   	return nb_rx;
>   }
>   
> @@ -456,6 +550,7 @@ eth_vhost_tx(void *q, struct rte_mbuf **bufs, uint16_t nb_bufs)
>   	uint16_t nb_send = 0;
>   	uint64_t nb_bytes = 0;
>   	uint64_t nb_missed = 0;
> +	uint16_t nb_pkts, num;
>   
>   	if (unlikely(rte_atomic32_read(&r->allow_queuing) == 0))
>   		return 0;
> @@ -486,31 +581,49 @@ eth_vhost_tx(void *q, struct rte_mbuf **bufs, uint16_t nb_bufs)
>   	}
>   
>   	/* Enqueue packets to guest RX queue */
> -	while (nb_send) {
> -		uint16_t nb_pkts;
> -		uint16_t num = (uint16_t)RTE_MIN(nb_send,
> -						 VHOST_MAX_PKT_BURST);
> +	if (!r->async_register) {
> +		while (nb_send) {
> +			num = (uint16_t)RTE_MIN(nb_send, VHOST_MAX_PKT_BURST);
> +			nb_pkts = rte_vhost_enqueue_burst(r->vid, r->virtqueue_id,
> +						&bufs[nb_tx], num);
> +
> +			nb_tx += nb_pkts;
> +			nb_send -= nb_pkts;
> +			if (nb_pkts < num)
> +				break;
> +		}
>   
> -		nb_pkts = rte_vhost_enqueue_burst(r->vid, r->virtqueue_id,
> -						  &bufs[nb_tx], num);
> +		for (i = 0; likely(i < nb_tx); i++) {
> +			nb_bytes += bufs[i]->pkt_len;
> +			rte_pktmbuf_free(bufs[i]);
> +		}
>   
> -		nb_tx += nb_pkts;
> -		nb_send -= nb_pkts;
> -		if (nb_pkts < num)
> -			break;
> -	}
> +	} else {
> +		while (nb_send) {
> +			num = (uint16_t)RTE_MIN(nb_send, VHOST_MAX_PKT_BURST);
> +			nb_pkts = rte_vhost_submit_enqueue_burst(r->vid, r->virtqueue_id,
> +							&bufs[nb_tx], num, r->dma_id, 0);
> +
> +			nb_tx += nb_pkts;
> +			nb_send -= nb_pkts;
> +			if (nb_pkts < num)
> +				break;
> +		}
>   
> -	for (i = 0; likely(i < nb_tx); i++)
> -		nb_bytes += bufs[i]->pkt_len;
> +		for (i = 0; likely(i < nb_tx); i++)
> +			nb_bytes += bufs[i]->pkt_len;
>   
> -	nb_missed = nb_bufs - nb_tx;
> +		if (unlikely(async_tx_poll_completed)) {
> +			vhost_tx_free_completed(r->vid, r->virtqueue_id, r->dma_id, r->cmpl_pkts,
> +					VHOST_MAX_PKT_BURST);
> +		}
> +	}
>   
> +	nb_missed = nb_bufs - nb_tx;
>   	r->stats.pkts += nb_tx;
>   	r->stats.bytes += nb_bytes;
>   	r->stats.missed_pkts += nb_missed;
>   
> -	for (i = 0; likely(i < nb_tx); i++)
> -		rte_pktmbuf_free(bufs[i]);
>   out:
>   	rte_atomic32_set(&r->while_queuing, 0);
>   
> @@ -798,6 +911,8 @@ queue_setup(struct rte_eth_dev *eth_dev, struct pmd_internal *internal)
>   		vq->vid = internal->vid;
>   		vq->internal = internal;
>   		vq->port = eth_dev->data->port_id;
> +		if (i < eth_dev->data->nb_tx_queues)
> +			vq->txq = eth_dev->data->tx_queues[i];
>   	}
>   	for (i = 0; i < eth_dev->data->nb_tx_queues; i++) {
>   		vq = eth_dev->data->tx_queues[i];
> @@ -878,6 +993,30 @@ new_device(int vid)
>   	return 0;
>   }
>   
> +static inline void
> +async_clear_virtqueue(int vid, uint16_t virtqueue_id, int16_t dma_id)
> +{
> +	struct rte_mbuf *pkts[VHOST_MAX_PKT_BURST];
> +	uint16_t i, ret, nr_done = 0;
> +
> +	if (vid == -1)
> +		return;
> +
> +	while (rte_vhost_async_get_inflight(vid, virtqueue_id) > 0) {
> +		ret = rte_vhost_clear_queue(vid, virtqueue_id, pkts, VHOST_MAX_PKT_BURST, dma_id,
> +				0);
> +		for (i = 0; i < ret ; i++)
> +			rte_pktmbuf_free(pkts[i]);
> +
> +		nr_done += ret;
> +	}
> +	VHOST_LOG(INFO, "Completed %u pkts for vid-%u vring-%u\n", nr_done, vid, virtqueue_id);
> +
> +	if (rte_vhost_async_channel_unregister(vid, virtqueue_id))
> +		VHOST_LOG(ERR, "Failed to unregister async for vid-%u vring-%u\n", vid,
> +				virtqueue_id);
> +}
> +
>   static void
>   destroy_device(int vid)
>   {
> @@ -908,13 +1047,27 @@ destroy_device(int vid)
>   			vq = eth_dev->data->rx_queues[i];
>   			if (!vq)
>   				continue;
> +			if (vq->async_register) {
> +				async_clear_virtqueue(vq->vid, vq->virtqueue_id,
> +							vq->dma_id);
> +				vq->async_register = false;
> +				internal->queue_dmas[vq->virtqueue_id].async_register = false;
> +			}
>   			vq->vid = -1;
> +
>   		}
>   		for (i = 0; i < eth_dev->data->nb_tx_queues; i++) {
>   			vq = eth_dev->data->tx_queues[i];
>   			if (!vq)
>   				continue;
> +			if (vq->async_register) {
> +				async_clear_virtqueue(vq->vid, vq->virtqueue_id,
> +							vq->dma_id);
> +				vq->async_register = false;
> +				internal->queue_dmas[vq->virtqueue_id].async_register = false;
> +			}
>   			vq->vid = -1;
> +
>   		}
>   	}
>   
> @@ -983,6 +1136,9 @@ vring_state_changed(int vid, uint16_t vring, int enable)
>   	struct rte_vhost_vring_state *state;
>   	struct rte_eth_dev *eth_dev;
>   	struct internal_list *list;
> +	struct vhost_queue *queue;
> +	struct pmd_internal *internal;
> +	int qid;
>   	char ifname[PATH_MAX];
>   
>   	rte_vhost_get_ifname(vid, ifname, sizeof(ifname));
> @@ -1011,6 +1167,65 @@ vring_state_changed(int vid, uint16_t vring, int enable)
>   
>   	update_queuing_status(eth_dev, false);
>   
> +	qid = vring / VIRTIO_QNUM;
> +	if (vring % VIRTIO_QNUM == VIRTIO_RXQ)
> +		queue = eth_dev->data->tx_queues[qid];
> +	else
> +		queue = eth_dev->data->rx_queues[qid];
> +
> +	if (!queue)
> +		goto skip;
> +
> +	internal = eth_dev->data->dev_private;
> +
> +	/* Register async data path for the queue assigned valid DMA device */
> +	if (internal->queue_dmas[queue->virtqueue_id].dma_id == INVALID_DMA_ID)
> +		goto skip;
> +
> +	if (enable && !queue->async_register) {
> +		if (rte_vhost_async_channel_register_thread_unsafe(vid, vring)) {
> +			VHOST_LOG(ERR, "Failed to register async for vid-%u vring-%u!\n", vid,
> +					vring);
> +			return -1;
> +		}
> +
> +		queue->async_register = true;
> +		internal->queue_dmas[vring].async_register = true;
> +
> +		VHOST_LOG(INFO, "Succeed to register async for vid-%u vring-%u\n", vid, vring);
> +	}
> +
> +	if (!enable && queue->async_register) {
> +		struct rte_mbuf *pkts[VHOST_MAX_PKT_BURST];
> +		uint16_t ret, i, nr_done = 0;
> +		uint16_t dma_id = queue->dma_id;
> +
> +		while (rte_vhost_async_get_inflight_thread_unsafe(vid, vring) > 0) {
> +			ret = rte_vhost_clear_queue_thread_unsafe(vid, vring, pkts,
> +					VHOST_MAX_PKT_BURST, dma_id, 0);
> +
> +			for (i = 0; i < ret ; i++)
> +				rte_pktmbuf_free(pkts[i]);
> +
> +			nr_done += ret;
> +		}
> +
> +		VHOST_LOG(INFO, "Completed %u in-flight pkts for vid-%u vring-%u\n", nr_done, vid,
> +				vring);
> +
> +		if (rte_vhost_async_channel_unregister_thread_unsafe(vid, vring)) {
> +			VHOST_LOG(ERR, "Failed to unregister async for vid-%u vring-%u\n", vid,
> +					vring);
> +			return -1;
> +		}
> +
> +		queue->async_register = false;
> +		internal->queue_dmas[vring].async_register = false;
> +
> +		VHOST_LOG(INFO, "Succeed to unregister async for vid-%u vring-%u\n", vid, vring);
> +	}
> +
> +skip:
>   	VHOST_LOG(INFO, "vring%u is %s\n",
>   			vring, enable ? "enabled" : "disabled");
>   
> @@ -1159,6 +1374,12 @@ rte_eth_vhost_get_vid_from_port_id(uint16_t port_id)
>   	return vid;
>   }
>   
> +void
> +rte_eth_vhost_async_tx_poll_completed(bool enable)
> +{
> +	async_tx_poll_completed = enable;
> +}
> +
>   static int
>   eth_dev_configure(struct rte_eth_dev *dev)
>   {
> @@ -1220,6 +1441,7 @@ eth_dev_close(struct rte_eth_dev *dev)
>   {
>   	struct pmd_internal *internal;
>   	struct internal_list *list;
> +	struct vhost_queue *queue;
>   	unsigned int i, ret;
>   
>   	if (rte_eal_process_type() != RTE_PROC_PRIMARY)
> @@ -1233,6 +1455,25 @@ eth_dev_close(struct rte_eth_dev *dev)
>   
>   	list = find_internal_resource(internal->iface_name);
>   	if (list) {
> +		/* Make sure all in-flight packets are completed before destroy vhost */
> +		if (dev->data->rx_queues) {
> +			for (i = 0; i < dev->data->nb_rx_queues; i++) {
> +				queue = dev->data->rx_queues[i];
> +				if (queue->async_register)
> +					async_clear_virtqueue(queue->vid, queue->virtqueue_id,
> +							queue->dma_id);
> +			}
> +		}
> +
> +		if (dev->data->tx_queues) {
> +			for (i = 0; i < dev->data->nb_tx_queues; i++) {
> +				queue = dev->data->tx_queues[i];
> +				if (queue->async_register)
> +					async_clear_virtqueue(queue->vid, queue->virtqueue_id,
> +							queue->dma_id);
> +			}
> +		}
> +
>   		rte_vhost_driver_unregister(internal->iface_name);
>   		pthread_mutex_lock(&internal_list_lock);
>   		TAILQ_REMOVE(&internal_list, list, next);
> @@ -1267,6 +1508,7 @@ eth_rx_queue_setup(struct rte_eth_dev *dev, uint16_t rx_queue_id,
>   		   struct rte_mempool *mb_pool)
>   {
>   	struct vhost_queue *vq;
> +	struct pmd_internal *internal = dev->data->dev_private;
>   
>   	vq = rte_zmalloc_socket(NULL, sizeof(struct vhost_queue),
>   			RTE_CACHE_LINE_SIZE, socket_id);
> @@ -1277,6 +1519,8 @@ eth_rx_queue_setup(struct rte_eth_dev *dev, uint16_t rx_queue_id,
>   
>   	vq->mb_pool = mb_pool;
>   	vq->virtqueue_id = rx_queue_id * VIRTIO_QNUM + VIRTIO_TXQ;
> +	vq->async_register = internal->queue_dmas[vq->virtqueue_id].async_register;
> +	vq->dma_id = internal->queue_dmas[vq->virtqueue_id].dma_id;
>   	rte_spinlock_init(&vq->intr_lock);
>   	dev->data->rx_queues[rx_queue_id] = vq;
>   
> @@ -1290,6 +1534,7 @@ eth_tx_queue_setup(struct rte_eth_dev *dev, uint16_t tx_queue_id,
>   		   const struct rte_eth_txconf *tx_conf __rte_unused)
>   {
>   	struct vhost_queue *vq;
> +	struct pmd_internal *internal = dev->data->dev_private;
>   
>   	vq = rte_zmalloc_socket(NULL, sizeof(struct vhost_queue),
>   			RTE_CACHE_LINE_SIZE, socket_id);
> @@ -1299,6 +1544,8 @@ eth_tx_queue_setup(struct rte_eth_dev *dev, uint16_t tx_queue_id,
>   	}
>   
>   	vq->virtqueue_id = tx_queue_id * VIRTIO_QNUM + VIRTIO_RXQ;
> +	vq->async_register = internal->queue_dmas[vq->virtqueue_id].async_register;
> +	vq->dma_id = internal->queue_dmas[vq->virtqueue_id].dma_id;
>   	rte_spinlock_init(&vq->intr_lock);
>   	dev->data->tx_queues[tx_queue_id] = vq;
>   
> @@ -1509,13 +1756,14 @@ static const struct eth_dev_ops ops = {
>   static int
>   eth_dev_vhost_create(struct rte_vdev_device *dev, char *iface_name,
>   	int16_t queues, const unsigned int numa_node, uint64_t flags,
> -	uint64_t disable_flags)
> +	uint64_t disable_flags, struct dma_input_info *dma_input)
>   {
>   	const char *name = rte_vdev_device_name(dev);
>   	struct rte_eth_dev_data *data;
>   	struct pmd_internal *internal = NULL;
>   	struct rte_eth_dev *eth_dev = NULL;
>   	struct rte_ether_addr *eth_addr = NULL;
> +	int i;
>   
>   	VHOST_LOG(INFO, "Creating VHOST-USER backend on numa socket %u\n",
>   		numa_node);
> @@ -1564,6 +1812,12 @@ eth_dev_vhost_create(struct rte_vdev_device *dev, char *iface_name,
>   	eth_dev->rx_pkt_burst = eth_vhost_rx;
>   	eth_dev->tx_pkt_burst = eth_vhost_tx;
>   
> +	for (i = 0; i < RTE_MAX_QUEUES_PER_PORT * 2; i++) {
> +		/* Invalid DMA ID indicates the queue does not want to enable async data path */
> +		internal->queue_dmas[i].dma_id = dma_input->dmas[i];
> +		internal->queue_dmas[i].async_register = false;
> +	}
> +
>   	rte_eth_dev_probing_finish(eth_dev);
>   	return 0;
>   
> @@ -1603,6 +1857,155 @@ open_int(const char *key __rte_unused, const char *value, void *extra_args)
>   	return 0;
>   }
>   
> +static int
> +init_dma(int16_t dma_id, uint16_t ring_size)
> +{
> +	struct rte_dma_info info;
> +	struct rte_dma_conf dev_config = { .nb_vchans = 1 };
> +	struct rte_dma_vchan_conf qconf = {
> +		.direction = RTE_DMA_DIR_MEM_TO_MEM,
> +	};
> +	int ret = 0;
> +
> +	if (dma_is_configured(dma_id))
> +		goto out;
> +
> +	if (rte_dma_info_get(dma_id, &info) != 0) {
> +		VHOST_LOG(ERR, "dma %u get info failed\n", dma_id);
> +		ret = -1;
> +		goto out;
> +	}
> +
> +	if (info.max_vchans < 1) {
> +		VHOST_LOG(ERR, "No channels available on dma %d\n", dma_id);
> +		ret = -1;
> +		goto out;
> +	}
> +
> +	if (rte_dma_configure(dma_id, &dev_config) != 0) {
> +		VHOST_LOG(ERR, "dma %u configure failed\n", dma_id);
> +		ret = -1;
> +		goto out;
> +	}
> +
> +	rte_dma_info_get(dma_id, &info);
> +	if (info.nb_vchans != 1) {
> +		VHOST_LOG(ERR, "dma %u has no queues\n", dma_id);
> +		ret = -1;
> +		goto out;
> +	}
> +
> +	ring_size = RTE_MAX(ring_size, MINIMUM_DMA_RING_SIZE);
> +	ring_size = RTE_MAX(ring_size, info.min_desc);
> +	qconf.nb_desc = RTE_MIN(ring_size, info.max_desc);
> +	if (rte_dma_vchan_setup(dma_id, 0, &qconf) != 0) {
> +		VHOST_LOG(ERR, "dma %u queue setup failed\n", dma_id);
> +		ret = -1;
> +		goto out;
> +	}
> +
> +	if (rte_dma_start(dma_id) != 0) {
> +		VHOST_LOG(ERR, "dma %u start failed\n", dma_id);
> +		ret = -1;
> +		goto out;
> +	}
> +
> +	configured_dmas[dma_count++] = dma_id;
> +
> +out:
> +	return ret;
> +}
> +
> +static int
> +open_dma(const char *key __rte_unused, const char *value, void *extra_args)
> +{
> +	struct dma_input_info *dma_input = extra_args;
> +	char *input = strndup(value, strlen(value) + 1);
> +	char *addrs = input;
> +	char *ptrs[2];
> +	char *start, *end, *substr;
> +	uint16_t qid, virtqueue_id;
> +	int16_t dma_id;
> +	int i, ret = 0;
> +
> +	while (isblank(*addrs))
> +		addrs++;
> +	if (*addrs == '\0') {
> +		VHOST_LOG(ERR, "No input DMA addresses\n");
> +		ret = -1;
> +		goto out;
> +	}
> +
> +	/* process DMA devices within bracket. */
> +	addrs++;
> +	substr = strtok(addrs, ";]");
> +	if (!substr) {
> +		VHOST_LOG(ERR, "No input DMA addresse\n");
> +		ret = -1;
> +		goto out;
> +	}
> +
> +	do {
> +		rte_strsplit(substr, strlen(substr), ptrs, 2, '@');
> +
> +		char *txq, *rxq;
> +		bool is_txq;
> +
> +		txq = strstr(ptrs[0], "txq");
> +		rxq = strstr(ptrs[0], "rxq");
> +		if (txq == NULL && rxq == NULL) {
> +			VHOST_LOG(ERR, "Illegal queue\n");
> +			ret = -1;
> +			goto out;
> +		} else if (txq) {
> +			is_txq = true;
> +			start = txq;
> +		} else {
> +			is_txq = false;
> +			start = rxq;
> +		}
> +
> +		start += 3;
> +		qid = strtol(start, &end, 0);
> +		if (end == start) {
> +			VHOST_LOG(ERR, "No input queue ID\n");
> +			ret = -1;
> +			goto out;
> +		}
> +
> +		virtqueue_id = is_txq ? qid * 2 + VIRTIO_RXQ : qid * 2 + VIRTIO_TXQ;
> +
> +		dma_id = rte_dma_get_dev_id_by_name(ptrs[1]);
> +		if (dma_id < 0) {
> +			VHOST_LOG(ERR, "Fail to find DMA device %s.\n", ptrs[1]);
> +			ret = -1;
> +			goto out;
> +		}
> +
> +		ret = init_dma(dma_id, dma_input->dma_ring_size);
> +		if (ret != 0) {
> +			VHOST_LOG(ERR, "Fail to initialize DMA %u\n", dma_id);
> +			ret = -1;
> +			break;
> +		}
> +
> +		dma_input->dmas[virtqueue_id] = dma_id;
> +
> +		substr = strtok(NULL, ";]");
> +	} while (substr);
> +
> +	for (i = 0; i < dma_count; i++) {
> +		if (rte_vhost_async_dma_configure(configured_dmas[i], 0) < 0) {
> +			VHOST_LOG(ERR, "Fail to configure DMA %u to vhost\n", configured_dmas[i]);
> +			ret = -1;
> +		}
> +	}
> +
> +out:
> +	free(input);
> +	return ret;
> +}
> +
>   static int
>   rte_pmd_vhost_probe(struct rte_vdev_device *dev)
>   {
> @@ -1621,6 +2024,10 @@ rte_pmd_vhost_probe(struct rte_vdev_device *dev)
>   	int legacy_ol_flags = 0;
>   	struct rte_eth_dev *eth_dev;
>   	const char *name = rte_vdev_device_name(dev);
> +	struct dma_input_info dma_input;
> +
> +	memset(dma_input.dmas, INVALID_DMA_ID, sizeof(dma_input.dmas));
> +	dma_input.dma_ring_size = DEFAULT_DMA_RING_SIZE;
>   
>   	VHOST_LOG(INFO, "Initializing pmd_vhost for %s\n", name);
>   
> @@ -1736,6 +2143,43 @@ rte_pmd_vhost_probe(struct rte_vdev_device *dev)
>   			goto out_free;
>   	}
>   
> +	if (rte_kvargs_count(kvlist, ETH_VHOST_DMA_RING_SIZE) == 1) {
> +		if (rte_kvargs_count(kvlist, ETH_VHOST_DMA_ARG) == 1) {
> +			ret = rte_kvargs_process(kvlist, ETH_VHOST_DMA_RING_SIZE,
> +					&open_int, &dma_input.dma_ring_size);
> +			if (ret < 0)
> +				goto out_free;
> +
> +			if (!rte_is_power_of_2(dma_input.dma_ring_size)) {
> +				dma_input.dma_ring_size = rte_align32pow2(dma_input.dma_ring_size);
> +				VHOST_LOG(INFO, "Convert dma_ring_size to the power of two %u\n",
> +						dma_input.dma_ring_size);
> +			}
> +		} else {
> +			VHOST_LOG(WARNING, "%s is not specified, skip to parse %s\n",
> +					ETH_VHOST_DMA_ARG, ETH_VHOST_DMA_RING_SIZE);
> +		}
> +	}
> +
> +	if (rte_kvargs_count(kvlist, ETH_VHOST_DMA_ARG) == 1) {
> +		if (rte_kvargs_count(kvlist, ETH_VHOST_DMA_RING_SIZE) == 0)
> +			VHOST_LOG(INFO, "Use default dma ring size %d\n", DEFAULT_DMA_RING_SIZE);
> +
> +		ret = rte_kvargs_process(kvlist, ETH_VHOST_DMA_ARG,
> +					 &open_dma, &dma_input);
> +		if (ret < 0) {
> +			VHOST_LOG(ERR, "Failed to parse %s\n", ETH_VHOST_DMA_ARG);
> +			goto out_free;
> +		}
> +
> +		flags |= RTE_VHOST_USER_ASYNC_COPY;
> +		/**
> +		 * Don't support live migration when enable
> +		 * DMA acceleration.
> +		 */
> +		disable_flags |= (1ULL << VHOST_F_LOG_ALL);
> +	}
> +
>   	if (legacy_ol_flags == 0)
>   		flags |= RTE_VHOST_USER_NET_COMPLIANT_OL_FLAGS;
>   
> @@ -1743,7 +2187,7 @@ rte_pmd_vhost_probe(struct rte_vdev_device *dev)
>   		dev->device.numa_node = rte_socket_id();
>   
>   	ret = eth_dev_vhost_create(dev, iface_name, queues,
> -				   dev->device.numa_node, flags, disable_flags);
> +			dev->device.numa_node, flags, disable_flags, &dma_input);
>   	if (ret == -1)
>   		VHOST_LOG(ERR, "Failed to create %s\n", name);
>   
> @@ -1787,4 +2231,6 @@ RTE_PMD_REGISTER_PARAM_STRING(net_vhost,
>   	"postcopy-support=<0|1> "
>   	"tso=<0|1> "
>   	"linear-buffer=<0|1> "
> -	"ext-buffer=<0|1>");
> +	"ext-buffer=<0|1> "
> +	"dma-ring-size=<int> "
> +	"dmas=[txq0@dma_addr;rxq0@dma_addr]");
> diff --git a/drivers/net/vhost/rte_eth_vhost.h b/drivers/net/vhost/rte_eth_vhost.h
> index 0e68b9f668..146c98803d 100644
> --- a/drivers/net/vhost/rte_eth_vhost.h
> +++ b/drivers/net/vhost/rte_eth_vhost.h
> @@ -52,6 +52,21 @@ int rte_eth_vhost_get_queue_event(uint16_t port_id,
>    */
>   int rte_eth_vhost_get_vid_from_port_id(uint16_t port_id);
>   
> +/**
> + * @warning
> + * @b EXPERIMENTAL: this API may change, or be removed, without prior notice
> + *
> + * By default, rte_vhost_poll_enqueue_completed() is called in Rx path.
> + * This function enables Tx path, rather than Rx path, to poll completed
> + * packets for vhost async enqueue operations. Note that virtio may never
> + * receive DMA completed packets if there are no more Tx operations.
> + *
> + * @param enable
> + *  True indicates Tx path to call rte_vhost_poll_enqueue_completed().
> + */
> +__rte_experimental
> +void rte_eth_vhost_async_tx_poll_completed(bool enable);
> +
>   #ifdef __cplusplus
>   }
>   #endif
> diff --git a/drivers/net/vhost/version.map b/drivers/net/vhost/version.map
> index e42c89f1eb..0a40441227 100644
> --- a/drivers/net/vhost/version.map
> +++ b/drivers/net/vhost/version.map
> @@ -6,3 +6,10 @@ DPDK_23 {
>   
>   	local: *;
>   };
> +
> +EXPERIMENTAL {
> +	global:
> +
> +	# added in 22.11
> +	rte_eth_vhost_async_tx_poll_completed;

I'm not in favor of adding driver-specific API.
IMHO, you should just decide whether doing completion on Tx or Rx path
and stick with it.

Doing completion on the Tx path not being reliable (i.e. if not other
packets are sent, last enqueued packets are not completed), I guess only
doing completion in Rx path is the right thing to do.

> +};
> diff --git a/drivers/net/vhost/vhost_testpmd.c b/drivers/net/vhost/vhost_testpmd.c
> new file mode 100644
> index 0000000000..11990ea152
> --- /dev/null
> +++ b/drivers/net/vhost/vhost_testpmd.c
> @@ -0,0 +1,67 @@
> +/* SPDX-License-Identifier: BSD-3-Clause
> + * Copyright(c) 2022 Intel Corporation.
> + */
> +#include <rte_eth_vhost.h>
> +#include <cmdline_parse_num.h>
> +#include <cmdline_parse_string.h>
> +
> +#include "testpmd.h"
> +
> +struct cmd_tx_poll_result {
> +	cmdline_fixed_string_t async_vhost;
> +	cmdline_fixed_string_t tx;
> +	cmdline_fixed_string_t poll;
> +	cmdline_fixed_string_t completed;
> +	cmdline_fixed_string_t what;
> +};
> +
> +static cmdline_parse_token_string_t cmd_tx_async_vhost =
> +	TOKEN_STRING_INITIALIZER(struct cmd_tx_poll_result, async_vhost, "async_vhost");
> +static cmdline_parse_token_string_t cmd_tx_tx =
> +	TOKEN_STRING_INITIALIZER(struct cmd_tx_poll_result, tx, "tx");
> +static cmdline_parse_token_string_t cmd_tx_poll =
> +	TOKEN_STRING_INITIALIZER(struct cmd_tx_poll_result, poll, "poll");
> +static cmdline_parse_token_string_t cmd_tx_completed =
> +	TOKEN_STRING_INITIALIZER(struct cmd_tx_poll_result, completed, "completed");
> +static cmdline_parse_token_string_t cmd_tx_what =
> +	TOKEN_STRING_INITIALIZER(struct cmd_tx_poll_result, what, "on#off");
> +
> +static void
> +cmd_tx_poll_parsed(void *parsed_result, __rte_unused struct cmdline *cl, __rte_unused void *data)
> +{
> +	struct cmd_tx_poll_result *res = parsed_result;
> +
> +	if (!strcmp(res->what, "on"))
> +		rte_eth_vhost_async_tx_poll_completed(true);
> +	else if (!strcmp(res->what, "off"))
> +		rte_eth_vhost_async_tx_poll_completed(false);
> +	else
> +		fprintf(stderr, "Unknown parameter\n");
> +}
> +
> +static cmdline_parse_inst_t async_vhost_cmd_tx_poll = {
> +	.f = cmd_tx_poll_parsed,
> +	.data = NULL,
> +	.help_str = "async-vhost tx poll completed on|off",
> +	.tokens = {
> +		(void *)&cmd_tx_async_vhost,
> +		(void *)&cmd_tx_tx,
> +		(void *)&cmd_tx_poll,
> +		(void *)&cmd_tx_completed,
> +		(void *)&cmd_tx_what,
> +		NULL,
> +	},
> +};
> +
> +static struct testpmd_driver_commands async_vhost_cmds = {
> +	.commands = {
> +	{
> +		&async_vhost_cmd_tx_poll,
> +		"async_vhost tx poll completed (on|off)\n"
> +		"    Poll and free DMA completed packets in Tx path.\n",
> +	},
> +	{ NULL, NULL },
> +	},
> +};
> +
> +TESTPMD_ADD_DRIVER_COMMANDS(async_vhost_cmds)
Wang, YuanX Oct. 24, 2022, 9:25 a.m. UTC | #3
Hi Chenbo,

> -----Original Message-----
> From: Xia, Chenbo <chenbo.xia@intel.com>
> Sent: Monday, October 24, 2022 5:03 PM
> To: Wang, YuanX <yuanx.wang@intel.com>; Maxime Coquelin
> <maxime.coquelin@redhat.com>
> Cc: dev@dpdk.org; Hu, Jiayu <jiayu.hu@intel.com>; Jiang, Cheng1
> <cheng1.jiang@intel.com>; Ma, WenwuX <wenwux.ma@intel.com>; He,
> Xingguang <xingguang.he@intel.com>
> Subject: RE: [PATCH v5] net/vhost: support asynchronous data path
> 
> Hi Yuan,
> 
> > -----Original Message-----
> > From: Wang, YuanX <yuanx.wang@intel.com>
> > Sent: Monday, October 24, 2022 11:15 PM
> > To: Maxime Coquelin <maxime.coquelin@redhat.com>; Xia, Chenbo
> > <chenbo.xia@intel.com>
> > Cc: dev@dpdk.org; Hu, Jiayu <jiayu.hu@intel.com>; Jiang, Cheng1
> > <cheng1.jiang@intel.com>; Ma, WenwuX <wenwux.ma@intel.com>; He,
> > Xingguang <xingguang.he@intel.com>; Wang, YuanX
> <yuanx.wang@intel.com>
> > Subject: [PATCH v5] net/vhost: support asynchronous data path
> >
> > Vhost asynchronous data-path offloads packet copy from the CPU to the
> > DMA engine. As a result, large packet copy can be accelerated by the
> > DMA engine, and vhost can free CPU cycles for higher level functions.
> >
> > In this patch, we enable asynchronous data-path for vhostpmd.
> > Asynchronous data path is enabled per tx/rx queue, and users need to
> > specify the DMA device used by the tx/rx queue. Each tx/rx queue only
> > supports to use one DMA device, but one DMA device can be shared
> among
> > multiple tx/rx queues of different vhost PMD ports.
> >
> > Two PMD parameters are added:
> > - dmas:	specify the used DMA device for a tx/rx queue.
> > 	(Default: no queues enable asynchronous data path)
> > - dma-ring-size: DMA ring size.
> > 	(Default: 4096).
> >
> > Here is an example:
> > --vdev
> >
> 'eth_vhost0,iface=./s0,dmas=[txq0@0000:00.01.0;rxq0@0000:00.01.1],dma-
> > ring-size=4096'
> >
> > Signed-off-by: Jiayu Hu <jiayu.hu@intel.com>
> > Signed-off-by: Yuan Wang <yuanx.wang@intel.com>
> > Signed-off-by: Wenwu Ma <wenwux.ma@intel.com>
> >
> 
> Sorry that I just realize that we need to change release notes because this is
> new feature for vhost PMD. Please mention the async support and new
> driver api you added.

Sure, will update docs in new version.

Thanks,
Yuan

> 
> Thanks,
> Chenbo
Hu, Jiayu Oct. 25, 2022, 2:14 a.m. UTC | #4
Hi Maxime,

Thanks for your comments. Please see replies inline.

> -----Original Message-----
> From: Maxime Coquelin <maxime.coquelin@redhat.com>
> Sent: Monday, October 24, 2022 5:08 PM
> To: Wang, YuanX <yuanx.wang@intel.com>; Xia, Chenbo
> <chenbo.xia@intel.com>
> Cc: dev@dpdk.org; Hu, Jiayu <jiayu.hu@intel.com>; Jiang, Cheng1
> <cheng1.jiang@intel.com>; Ma, WenwuX <wenwux.ma@intel.com>; He,
> Xingguang <xingguang.he@intel.com>
> Subject: Re: [PATCH v5] net/vhost: support asynchronous data path
> 
> Hi Yuan,
> 
> Please fix your system for the next times, your patch is dated several hours in
> the future.
> 
> On 10/24/22 17:14, Yuan Wang wrote:
> > Vhost asynchronous data-path offloads packet copy from the CPU to the
> > DMA engine. As a result, large packet copy can be accelerated by the
> > DMA engine, and vhost can free CPU cycles for higher level
> 
> Vhost
> 
> > functions.
> >
> > In this patch, we enable asynchronous data-path for vhostpmd.
> > Asynchronous data path is enabled per tx/rx queue, and users need to
> > specify the DMA device used by the tx/rx queue. Each tx/rx queue only
> > supports to use one DMA device, but one DMA device can be shared
> among
> > multiple tx/rx queues of different vhost PMD ports.
> >
> > Two PMD parameters are added:
> > - dmas:	specify the used DMA device for a tx/rx queue.
> > 	(Default: no queues enable asynchronous data path)
> > - dma-ring-size: DMA ring size.
> > 	(Default: 4096).
> >
> > Here is an example:
> > --vdev
> 'eth_vhost0,iface=./s0,dmas=[txq0@0000:00.01.0;rxq0@0000:00.01.1],dma-
> ring-size=4096'
> >
> > Signed-off-by: Jiayu Hu <jiayu.hu@intel.com>
> > Signed-off-by: Yuan Wang <yuanx.wang@intel.com>
> > Signed-off-by: Wenwu Ma <wenwux.ma@intel.com>
> >
> > ---
> > v5:
> > - add error log of testpmd cmd
> >
> > v4:
> > - add txq allow_queuing check on poll completed
> > - unregister dma channel in destroy_device
> > - add dma ring size minimum limit
> > - fix serveral code style and logging issues
> >
> > v3:
> > - add the API to version.map
> >
> > v2:
> > - add missing file
> > - hide async_tx_poll_completed
> > - change default DMA ring size to 4096
> >
> > ---
> >   drivers/net/vhost/meson.build     |   1 +
> >   drivers/net/vhost/rte_eth_vhost.c | 512
> ++++++++++++++++++++++++++++--
> >   drivers/net/vhost/rte_eth_vhost.h |  15 +
> >   drivers/net/vhost/version.map     |   7 +
> >   drivers/net/vhost/vhost_testpmd.c |  67 ++++
> >   5 files changed, 569 insertions(+), 33 deletions(-)
> >   create mode 100644 drivers/net/vhost/vhost_testpmd.c
> >
> > diff --git a/drivers/net/vhost/meson.build
> > b/drivers/net/vhost/meson.build index f481a3a4b8..22a0ab3a58 100644
> > --- a/drivers/net/vhost/meson.build
> > +++ b/drivers/net/vhost/meson.build
> > @@ -9,4 +9,5 @@ endif
> >
> >   deps += 'vhost'
> >   sources = files('rte_eth_vhost.c')
> > +testpmd_sources = files('vhost_testpmd.c')
> >   headers = files('rte_eth_vhost.h')
> > diff --git a/drivers/net/vhost/rte_eth_vhost.c
> > b/drivers/net/vhost/rte_eth_vhost.c
> > index b152279fac..80cd9c8d92 100644
> > --- a/drivers/net/vhost/rte_eth_vhost.c
> > +++ b/drivers/net/vhost/rte_eth_vhost.c
> > @@ -7,6 +7,7 @@
> >   #include <pthread.h>
> >   #include <stdbool.h>
> >   #include <sys/epoll.h>
> > +#include <ctype.h>
> >
> >   #include <rte_mbuf.h>
> >   #include <ethdev_driver.h>
> > @@ -18,6 +19,8 @@
> >   #include <rte_kvargs.h>
> >   #include <rte_vhost.h>
> >   #include <rte_spinlock.h>
> > +#include <rte_vhost_async.h>
> > +#include <rte_dmadev.h>
> >
> >   #include "rte_eth_vhost.h"
> >
> > @@ -37,8 +40,15 @@ enum {VIRTIO_RXQ, VIRTIO_TXQ, VIRTIO_QNUM};
> >   #define ETH_VHOST_LINEAR_BUF		"linear-buffer"
> >   #define ETH_VHOST_EXT_BUF		"ext-buffer"
> >   #define ETH_VHOST_LEGACY_OL_FLAGS	"legacy-ol-flags"
> > +#define ETH_VHOST_DMA_ARG		"dmas"
> > +#define ETH_VHOST_DMA_RING_SIZE		"dma-ring-size"
> >   #define VHOST_MAX_PKT_BURST 32
> >
> > +#define INVALID_DMA_ID		-1
> > +#define DEFAULT_DMA_RING_SIZE	4096
> > +/* Minimum package size is 64, dma ring size should be greater than 32 */
> > +#define MINIMUM_DMA_RING_SIZE	64
> 
> Why? Is that related to Intel HW?

No, it is for TCP/UDP tests. The max TCP/UDP length is 64KB, so one packet
needs 32 pktmbufs. If we set DMA ring size to 32, it's possible that vhost cannot
enqueue/dequeue one packet, as there may be some control packets mixed and
DMA ring full will cause enqueue/dequeue the packet failed. So the recommend
minimal DMA ring size is > 32.

We can remove the macro, but add one comment to suggest the DMA ring
size.
> 
> > +
> >   static const char *valid_arguments[] = {
> >   	ETH_VHOST_IFACE_ARG,
> >   	ETH_VHOST_QUEUES_ARG,
> > @@ -49,6 +59,8 @@ static const char *valid_arguments[] = {
> >   	ETH_VHOST_LINEAR_BUF,
> >   	ETH_VHOST_EXT_BUF,
> >   	ETH_VHOST_LEGACY_OL_FLAGS,
> > +	ETH_VHOST_DMA_ARG,
> > +	ETH_VHOST_DMA_RING_SIZE,
> >   	NULL
> >   };
> >
> > @@ -80,8 +92,39 @@ struct vhost_queue {
> >   	struct vhost_stats stats;
> >   	int intr_enable;
> >   	rte_spinlock_t intr_lock;
> > +
> > +	/* Flag of enabling async data path */
> > +	bool async_register;
> > +	/* DMA device ID */
> > +	int16_t dma_id;
> > +	/**
> > +	 * For a Rx queue, "txq" points to its peer Tx queue.
> > +	 * For a Tx queue, "txq" is never used.
> > +	 */
> > +	struct vhost_queue *txq;
> > +	/* Array to keep DMA completed packets */
> > +	struct rte_mbuf *cmpl_pkts[VHOST_MAX_PKT_BURST];
> >   };
> >
> > +struct dma_input_info {
> > +	int16_t dmas[RTE_MAX_QUEUES_PER_PORT * 2];
> > +	uint16_t dma_ring_size;
> > +};
> > +
> > +static int16_t configured_dmas[RTE_DMADEV_DEFAULT_MAX];
> > +static int dma_count;
> > +
> > +/**
> > + * By default, its Rx path to call rte_vhost_poll_enqueue_completed() for
> enqueue operations.
> > + * However, Rx function is never been called in testpmd "txonly"
> > +mode, thus causing virtio
> > + * cannot receive DMA completed packets. To make txonly mode work
> > +correctly, we provide a
> > + * command in testpmd to call rte_vhost_poll_enqueue_completed() in Tx
> path.
> > + *
> > + * When set async_tx_poll_completed to true, Tx path calls
> > +rte_vhost_poll_enqueue_completed();
> > + * otherwise, Rx path calls it.
> > + */
> > +bool async_tx_poll_completed;
> > +
> >   struct pmd_internal {
> >   	rte_atomic32_t dev_attached;
> >   	char *iface_name;
> > @@ -94,6 +137,10 @@ struct pmd_internal {
> >   	bool vlan_strip;
> >   	bool rx_sw_csum;
> >   	bool tx_sw_csum;
> > +	struct {
> > +		int16_t dma_id;
> > +		bool async_register;
> > +	} queue_dmas[RTE_MAX_QUEUES_PER_PORT * 2];
> >   };
> >
> >   struct internal_list {
> > @@ -124,6 +171,17 @@ struct rte_vhost_vring_state {
> >
> >   static struct rte_vhost_vring_state *vring_states[RTE_MAX_ETHPORTS];
> >
> > +static bool
> > +dma_is_configured(int16_t dma_id)
> > +{
> > +	int i;
> > +
> > +	for (i = 0; i < dma_count; i++)
> > +		if (configured_dmas[i] == dma_id)
> > +			return true;
> > +	return false;
> > +}
> > +
> >   static int
> >   vhost_dev_xstats_reset(struct rte_eth_dev *dev)
> >   {
> > @@ -396,15 +454,27 @@ vhost_dev_rx_sw_csum(struct rte_mbuf *mbuf)
> >   	mbuf->ol_flags |= RTE_MBUF_F_RX_L4_CKSUM_GOOD;
> >   }
> >
> > +static inline void
> > +vhost_tx_free_completed(int vid, uint16_t virtqueue_id, int16_t dma_id,
> > +		struct rte_mbuf **pkts, uint16_t count) {
> > +	uint16_t i, ret;
> > +
> > +	ret = rte_vhost_poll_enqueue_completed(vid, virtqueue_id, pkts,
> count, dma_id, 0);
> > +	for (i = 0; likely(i < ret); i++)
> > +		rte_pktmbuf_free(pkts[i]);
> > +}
> > +
> >   static uint16_t
> >   eth_vhost_rx(void *q, struct rte_mbuf **bufs, uint16_t nb_bufs)
> >   {
> >   	struct vhost_queue *r = q;
> >   	uint16_t i, nb_rx = 0;
> >   	uint16_t nb_receive = nb_bufs;
> > +	uint16_t nb_pkts, num;
> >
> >   	if (unlikely(rte_atomic32_read(&r->allow_queuing) == 0))
> > -		return 0;
> > +		goto tx_poll;
> >
> >   	rte_atomic32_set(&r->while_queuing, 1);
> >
> > @@ -412,19 +482,32 @@ eth_vhost_rx(void *q, struct rte_mbuf **bufs,
> uint16_t nb_bufs)
> >   		goto out;
> >
> >   	/* Dequeue packets from guest TX queue */
> > -	while (nb_receive) {
> > -		uint16_t nb_pkts;
> > -		uint16_t num = (uint16_t)RTE_MIN(nb_receive,
> > -						 VHOST_MAX_PKT_BURST);
> > -
> > -		nb_pkts = rte_vhost_dequeue_burst(r->vid, r->virtqueue_id,
> > -						  r->mb_pool, &bufs[nb_rx],
> > -						  num);
> > -
> > -		nb_rx += nb_pkts;
> > -		nb_receive -= nb_pkts;
> > -		if (nb_pkts < num)
> > -			break;
> > +	if (!r->async_register) {
> > +		while (nb_receive) {
> > +			num = (uint16_t)RTE_MIN(nb_receive,
> VHOST_MAX_PKT_BURST);
> > +			nb_pkts = rte_vhost_dequeue_burst(r->vid, r-
> >virtqueue_id,
> > +						r->mb_pool, &bufs[nb_rx],
> > +						num);
> > +
> > +			nb_rx += nb_pkts;
> > +			nb_receive -= nb_pkts;
> > +			if (nb_pkts < num)
> > +				break;
> > +		}
> > +	} else {
> > +		int nr_inflight;
> > +
> > +		while (nb_receive) {
> > +			num = (uint16_t)RTE_MIN(nb_receive,
> VHOST_MAX_PKT_BURST);
> > +			nb_pkts = rte_vhost_async_try_dequeue_burst(r-
> >vid, r->virtqueue_id,
> > +						r->mb_pool, &bufs[nb_rx],
> num, &nr_inflight,
> > +						r->dma_id, 0);
> > +
> > +			nb_rx += nb_pkts;
> > +			nb_receive -= nb_pkts;
> > +			if (nb_pkts < num)
> > +				break;
> > +		}
> >   	}
> >
> >   	r->stats.pkts += nb_rx;
> > @@ -445,6 +528,17 @@ eth_vhost_rx(void *q, struct rte_mbuf **bufs,
> uint16_t nb_bufs)
> >   out:
> >   	rte_atomic32_set(&r->while_queuing, 0);
> >
> > +tx_poll:
> > +	/**
> > +	 * Poll and free completed packets for the virtqueue of Tx queue.
> > +	 * Note that we access Tx queue's virtqueue, which is protected
> > +	 * by vring lock.
> > +	 */
> > +	if (r->txq->async_register && !async_tx_poll_completed &&
> > +			rte_atomic32_read(&r->txq->allow_queuing) == 1)
> > +		vhost_tx_free_completed(r->vid, r->txq->virtqueue_id, r-
> >txq->dma_id,
> > +				r->cmpl_pkts, VHOST_MAX_PKT_BURST);
> > +
> >   	return nb_rx;
> >   }
> >
> > @@ -456,6 +550,7 @@ eth_vhost_tx(void *q, struct rte_mbuf **bufs,
> uint16_t nb_bufs)
> >   	uint16_t nb_send = 0;
> >   	uint64_t nb_bytes = 0;
> >   	uint64_t nb_missed = 0;
> > +	uint16_t nb_pkts, num;
> >
> >   	if (unlikely(rte_atomic32_read(&r->allow_queuing) == 0))
> >   		return 0;
> > @@ -486,31 +581,49 @@ eth_vhost_tx(void *q, struct rte_mbuf **bufs,
> uint16_t nb_bufs)
> >   	}
> >
> >   	/* Enqueue packets to guest RX queue */
> > -	while (nb_send) {
> > -		uint16_t nb_pkts;
> > -		uint16_t num = (uint16_t)RTE_MIN(nb_send,
> > -						 VHOST_MAX_PKT_BURST);
> > +	if (!r->async_register) {
> > +		while (nb_send) {
> > +			num = (uint16_t)RTE_MIN(nb_send,
> VHOST_MAX_PKT_BURST);
> > +			nb_pkts = rte_vhost_enqueue_burst(r->vid, r-
> >virtqueue_id,
> > +						&bufs[nb_tx], num);
> > +
> > +			nb_tx += nb_pkts;
> > +			nb_send -= nb_pkts;
> > +			if (nb_pkts < num)
> > +				break;
> > +		}
> >
> > -		nb_pkts = rte_vhost_enqueue_burst(r->vid, r->virtqueue_id,
> > -						  &bufs[nb_tx], num);
> > +		for (i = 0; likely(i < nb_tx); i++) {
> > +			nb_bytes += bufs[i]->pkt_len;
> > +			rte_pktmbuf_free(bufs[i]);
> > +		}
> >
> > -		nb_tx += nb_pkts;
> > -		nb_send -= nb_pkts;
> > -		if (nb_pkts < num)
> > -			break;
> > -	}
> > +	} else {
> > +		while (nb_send) {
> > +			num = (uint16_t)RTE_MIN(nb_send,
> VHOST_MAX_PKT_BURST);
> > +			nb_pkts = rte_vhost_submit_enqueue_burst(r->vid,
> r->virtqueue_id,
> > +							&bufs[nb_tx], num, r-
> >dma_id, 0);
> > +
> > +			nb_tx += nb_pkts;
> > +			nb_send -= nb_pkts;
> > +			if (nb_pkts < num)
> > +				break;
> > +		}
> >
> > -	for (i = 0; likely(i < nb_tx); i++)
> > -		nb_bytes += bufs[i]->pkt_len;
> > +		for (i = 0; likely(i < nb_tx); i++)
> > +			nb_bytes += bufs[i]->pkt_len;
> >
> > -	nb_missed = nb_bufs - nb_tx;
> > +		if (unlikely(async_tx_poll_completed)) {
> > +			vhost_tx_free_completed(r->vid, r->virtqueue_id, r-
> >dma_id, r->cmpl_pkts,
> > +					VHOST_MAX_PKT_BURST);
> > +		}
> > +	}
> >
> > +	nb_missed = nb_bufs - nb_tx;
> >   	r->stats.pkts += nb_tx;
> >   	r->stats.bytes += nb_bytes;
> >   	r->stats.missed_pkts += nb_missed;
> >
> > -	for (i = 0; likely(i < nb_tx); i++)
> > -		rte_pktmbuf_free(bufs[i]);
> >   out:
> >   	rte_atomic32_set(&r->while_queuing, 0);
> >
> > @@ -798,6 +911,8 @@ queue_setup(struct rte_eth_dev *eth_dev, struct
> pmd_internal *internal)
> >   		vq->vid = internal->vid;
> >   		vq->internal = internal;
> >   		vq->port = eth_dev->data->port_id;
> > +		if (i < eth_dev->data->nb_tx_queues)
> > +			vq->txq = eth_dev->data->tx_queues[i];
> >   	}
> >   	for (i = 0; i < eth_dev->data->nb_tx_queues; i++) {
> >   		vq = eth_dev->data->tx_queues[i];
> > @@ -878,6 +993,30 @@ new_device(int vid)
> >   	return 0;
> >   }
> >
> > +static inline void
> > +async_clear_virtqueue(int vid, uint16_t virtqueue_id, int16_t dma_id)
> > +{
> > +	struct rte_mbuf *pkts[VHOST_MAX_PKT_BURST];
> > +	uint16_t i, ret, nr_done = 0;
> > +
> > +	if (vid == -1)
> > +		return;
> > +
> > +	while (rte_vhost_async_get_inflight(vid, virtqueue_id) > 0) {
> > +		ret = rte_vhost_clear_queue(vid, virtqueue_id, pkts,
> VHOST_MAX_PKT_BURST, dma_id,
> > +				0);
> > +		for (i = 0; i < ret ; i++)
> > +			rte_pktmbuf_free(pkts[i]);
> > +
> > +		nr_done += ret;
> > +	}
> > +	VHOST_LOG(INFO, "Completed %u pkts for vid-%u vring-%u\n",
> nr_done,
> > +vid, virtqueue_id);
> > +
> > +	if (rte_vhost_async_channel_unregister(vid, virtqueue_id))
> > +		VHOST_LOG(ERR, "Failed to unregister async for vid-%u
> vring-%u\n", vid,
> > +				virtqueue_id);
> > +}
> > +
> >   static void
> >   destroy_device(int vid)
> >   {
> > @@ -908,13 +1047,27 @@ destroy_device(int vid)
> >   			vq = eth_dev->data->rx_queues[i];
> >   			if (!vq)
> >   				continue;
> > +			if (vq->async_register) {
> > +				async_clear_virtqueue(vq->vid, vq-
> >virtqueue_id,
> > +							vq->dma_id);
> > +				vq->async_register = false;
> > +				internal->queue_dmas[vq-
> >virtqueue_id].async_register = false;
> > +			}
> >   			vq->vid = -1;
> > +
> >   		}
> >   		for (i = 0; i < eth_dev->data->nb_tx_queues; i++) {
> >   			vq = eth_dev->data->tx_queues[i];
> >   			if (!vq)
> >   				continue;
> > +			if (vq->async_register) {
> > +				async_clear_virtqueue(vq->vid, vq-
> >virtqueue_id,
> > +							vq->dma_id);
> > +				vq->async_register = false;
> > +				internal->queue_dmas[vq-
> >virtqueue_id].async_register = false;
> > +			}
> >   			vq->vid = -1;
> > +
> >   		}
> >   	}
> >
> > @@ -983,6 +1136,9 @@ vring_state_changed(int vid, uint16_t vring, int
> enable)
> >   	struct rte_vhost_vring_state *state;
> >   	struct rte_eth_dev *eth_dev;
> >   	struct internal_list *list;
> > +	struct vhost_queue *queue;
> > +	struct pmd_internal *internal;
> > +	int qid;
> >   	char ifname[PATH_MAX];
> >
> >   	rte_vhost_get_ifname(vid, ifname, sizeof(ifname)); @@ -1011,6
> > +1167,65 @@ vring_state_changed(int vid, uint16_t vring, int enable)
> >
> >   	update_queuing_status(eth_dev, false);
> >
> > +	qid = vring / VIRTIO_QNUM;
> > +	if (vring % VIRTIO_QNUM == VIRTIO_RXQ)
> > +		queue = eth_dev->data->tx_queues[qid];
> > +	else
> > +		queue = eth_dev->data->rx_queues[qid];
> > +
> > +	if (!queue)
> > +		goto skip;
> > +
> > +	internal = eth_dev->data->dev_private;
> > +
> > +	/* Register async data path for the queue assigned valid DMA device
> */
> > +	if (internal->queue_dmas[queue->virtqueue_id].dma_id ==
> INVALID_DMA_ID)
> > +		goto skip;
> > +
> > +	if (enable && !queue->async_register) {
> > +		if (rte_vhost_async_channel_register_thread_unsafe(vid,
> vring)) {
> > +			VHOST_LOG(ERR, "Failed to register async for vid-%u
> vring-%u!\n", vid,
> > +					vring);
> > +			return -1;
> > +		}
> > +
> > +		queue->async_register = true;
> > +		internal->queue_dmas[vring].async_register = true;
> > +
> > +		VHOST_LOG(INFO, "Succeed to register async for vid-%u
> vring-%u\n", vid, vring);
> > +	}
> > +
> > +	if (!enable && queue->async_register) {
> > +		struct rte_mbuf *pkts[VHOST_MAX_PKT_BURST];
> > +		uint16_t ret, i, nr_done = 0;
> > +		uint16_t dma_id = queue->dma_id;
> > +
> > +		while (rte_vhost_async_get_inflight_thread_unsafe(vid,
> vring) > 0) {
> > +			ret = rte_vhost_clear_queue_thread_unsafe(vid,
> vring, pkts,
> > +					VHOST_MAX_PKT_BURST, dma_id, 0);
> > +
> > +			for (i = 0; i < ret ; i++)
> > +				rte_pktmbuf_free(pkts[i]);
> > +
> > +			nr_done += ret;
> > +		}
> > +
> > +		VHOST_LOG(INFO, "Completed %u in-flight pkts for vid-%u
> vring-%u\n", nr_done, vid,
> > +				vring);
> > +
> > +		if (rte_vhost_async_channel_unregister_thread_unsafe(vid,
> vring)) {
> > +			VHOST_LOG(ERR, "Failed to unregister async for vid-
> %u vring-%u\n", vid,
> > +					vring);
> > +			return -1;
> > +		}
> > +
> > +		queue->async_register = false;
> > +		internal->queue_dmas[vring].async_register = false;
> > +
> > +		VHOST_LOG(INFO, "Succeed to unregister async for vid-%u
> vring-%u\n", vid, vring);
> > +	}
> > +
> > +skip:
> >   	VHOST_LOG(INFO, "vring%u is %s\n",
> >   			vring, enable ? "enabled" : "disabled");
> >
> > @@ -1159,6 +1374,12 @@ rte_eth_vhost_get_vid_from_port_id(uint16_t
> port_id)
> >   	return vid;
> >   }
> >
> > +void
> > +rte_eth_vhost_async_tx_poll_completed(bool enable) {
> > +	async_tx_poll_completed = enable;
> > +}
> > +
> >   static int
> >   eth_dev_configure(struct rte_eth_dev *dev)
> >   {
> > @@ -1220,6 +1441,7 @@ eth_dev_close(struct rte_eth_dev *dev)
> >   {
> >   	struct pmd_internal *internal;
> >   	struct internal_list *list;
> > +	struct vhost_queue *queue;
> >   	unsigned int i, ret;
> >
> >   	if (rte_eal_process_type() != RTE_PROC_PRIMARY) @@ -1233,6
> +1455,25
> > @@ eth_dev_close(struct rte_eth_dev *dev)
> >
> >   	list = find_internal_resource(internal->iface_name);
> >   	if (list) {
> > +		/* Make sure all in-flight packets are completed before
> destroy vhost */
> > +		if (dev->data->rx_queues) {
> > +			for (i = 0; i < dev->data->nb_rx_queues; i++) {
> > +				queue = dev->data->rx_queues[i];
> > +				if (queue->async_register)
> > +					async_clear_virtqueue(queue->vid,
> queue->virtqueue_id,
> > +							queue->dma_id);
> > +			}
> > +		}
> > +
> > +		if (dev->data->tx_queues) {
> > +			for (i = 0; i < dev->data->nb_tx_queues; i++) {
> > +				queue = dev->data->tx_queues[i];
> > +				if (queue->async_register)
> > +					async_clear_virtqueue(queue->vid,
> queue->virtqueue_id,
> > +							queue->dma_id);
> > +			}
> > +		}
> > +
> >   		rte_vhost_driver_unregister(internal->iface_name);
> >   		pthread_mutex_lock(&internal_list_lock);
> >   		TAILQ_REMOVE(&internal_list, list, next); @@ -1267,6
> +1508,7 @@
> > eth_rx_queue_setup(struct rte_eth_dev *dev, uint16_t rx_queue_id,
> >   		   struct rte_mempool *mb_pool)
> >   {
> >   	struct vhost_queue *vq;
> > +	struct pmd_internal *internal = dev->data->dev_private;
> >
> >   	vq = rte_zmalloc_socket(NULL, sizeof(struct vhost_queue),
> >   			RTE_CACHE_LINE_SIZE, socket_id);
> > @@ -1277,6 +1519,8 @@ eth_rx_queue_setup(struct rte_eth_dev *dev,
> > uint16_t rx_queue_id,
> >
> >   	vq->mb_pool = mb_pool;
> >   	vq->virtqueue_id = rx_queue_id * VIRTIO_QNUM + VIRTIO_TXQ;
> > +	vq->async_register = internal->queue_dmas[vq-
> >virtqueue_id].async_register;
> > +	vq->dma_id = internal->queue_dmas[vq->virtqueue_id].dma_id;
> >   	rte_spinlock_init(&vq->intr_lock);
> >   	dev->data->rx_queues[rx_queue_id] = vq;
> >
> > @@ -1290,6 +1534,7 @@ eth_tx_queue_setup(struct rte_eth_dev *dev,
> uint16_t tx_queue_id,
> >   		   const struct rte_eth_txconf *tx_conf __rte_unused)
> >   {
> >   	struct vhost_queue *vq;
> > +	struct pmd_internal *internal = dev->data->dev_private;
> >
> >   	vq = rte_zmalloc_socket(NULL, sizeof(struct vhost_queue),
> >   			RTE_CACHE_LINE_SIZE, socket_id);
> > @@ -1299,6 +1544,8 @@ eth_tx_queue_setup(struct rte_eth_dev *dev,
> uint16_t tx_queue_id,
> >   	}
> >
> >   	vq->virtqueue_id = tx_queue_id * VIRTIO_QNUM + VIRTIO_RXQ;
> > +	vq->async_register = internal->queue_dmas[vq-
> >virtqueue_id].async_register;
> > +	vq->dma_id = internal->queue_dmas[vq->virtqueue_id].dma_id;
> >   	rte_spinlock_init(&vq->intr_lock);
> >   	dev->data->tx_queues[tx_queue_id] = vq;
> >
> > @@ -1509,13 +1756,14 @@ static const struct eth_dev_ops ops = {
> >   static int
> >   eth_dev_vhost_create(struct rte_vdev_device *dev, char *iface_name,
> >   	int16_t queues, const unsigned int numa_node, uint64_t flags,
> > -	uint64_t disable_flags)
> > +	uint64_t disable_flags, struct dma_input_info *dma_input)
> >   {
> >   	const char *name = rte_vdev_device_name(dev);
> >   	struct rte_eth_dev_data *data;
> >   	struct pmd_internal *internal = NULL;
> >   	struct rte_eth_dev *eth_dev = NULL;
> >   	struct rte_ether_addr *eth_addr = NULL;
> > +	int i;
> >
> >   	VHOST_LOG(INFO, "Creating VHOST-USER backend on numa
> socket %u\n",
> >   		numa_node);
> > @@ -1564,6 +1812,12 @@ eth_dev_vhost_create(struct rte_vdev_device
> *dev, char *iface_name,
> >   	eth_dev->rx_pkt_burst = eth_vhost_rx;
> >   	eth_dev->tx_pkt_burst = eth_vhost_tx;
> >
> > +	for (i = 0; i < RTE_MAX_QUEUES_PER_PORT * 2; i++) {
> > +		/* Invalid DMA ID indicates the queue does not want to
> enable async data path */
> > +		internal->queue_dmas[i].dma_id = dma_input->dmas[i];
> > +		internal->queue_dmas[i].async_register = false;
> > +	}
> > +
> >   	rte_eth_dev_probing_finish(eth_dev);
> >   	return 0;
> >
> > @@ -1603,6 +1857,155 @@ open_int(const char *key __rte_unused, const
> char *value, void *extra_args)
> >   	return 0;
> >   }
> >
> > +static int
> > +init_dma(int16_t dma_id, uint16_t ring_size) {
> > +	struct rte_dma_info info;
> > +	struct rte_dma_conf dev_config = { .nb_vchans = 1 };
> > +	struct rte_dma_vchan_conf qconf = {
> > +		.direction = RTE_DMA_DIR_MEM_TO_MEM,
> > +	};
> > +	int ret = 0;
> > +
> > +	if (dma_is_configured(dma_id))
> > +		goto out;
> > +
> > +	if (rte_dma_info_get(dma_id, &info) != 0) {
> > +		VHOST_LOG(ERR, "dma %u get info failed\n", dma_id);
> > +		ret = -1;
> > +		goto out;
> > +	}
> > +
> > +	if (info.max_vchans < 1) {
> > +		VHOST_LOG(ERR, "No channels available on dma %d\n",
> dma_id);
> > +		ret = -1;
> > +		goto out;
> > +	}
> > +
> > +	if (rte_dma_configure(dma_id, &dev_config) != 0) {
> > +		VHOST_LOG(ERR, "dma %u configure failed\n", dma_id);
> > +		ret = -1;
> > +		goto out;
> > +	}
> > +
> > +	rte_dma_info_get(dma_id, &info);
> > +	if (info.nb_vchans != 1) {
> > +		VHOST_LOG(ERR, "dma %u has no queues\n", dma_id);
> > +		ret = -1;
> > +		goto out;
> > +	}
> > +
> > +	ring_size = RTE_MAX(ring_size, MINIMUM_DMA_RING_SIZE);
> > +	ring_size = RTE_MAX(ring_size, info.min_desc);
> > +	qconf.nb_desc = RTE_MIN(ring_size, info.max_desc);
> > +	if (rte_dma_vchan_setup(dma_id, 0, &qconf) != 0) {
> > +		VHOST_LOG(ERR, "dma %u queue setup failed\n", dma_id);
> > +		ret = -1;
> > +		goto out;
> > +	}
> > +
> > +	if (rte_dma_start(dma_id) != 0) {
> > +		VHOST_LOG(ERR, "dma %u start failed\n", dma_id);
> > +		ret = -1;
> > +		goto out;
> > +	}
> > +
> > +	configured_dmas[dma_count++] = dma_id;
> > +
> > +out:
> > +	return ret;
> > +}
> > +
> > +static int
> > +open_dma(const char *key __rte_unused, const char *value, void
> > +*extra_args) {
> > +	struct dma_input_info *dma_input = extra_args;
> > +	char *input = strndup(value, strlen(value) + 1);
> > +	char *addrs = input;
> > +	char *ptrs[2];
> > +	char *start, *end, *substr;
> > +	uint16_t qid, virtqueue_id;
> > +	int16_t dma_id;
> > +	int i, ret = 0;
> > +
> > +	while (isblank(*addrs))
> > +		addrs++;
> > +	if (*addrs == '\0') {
> > +		VHOST_LOG(ERR, "No input DMA addresses\n");
> > +		ret = -1;
> > +		goto out;
> > +	}
> > +
> > +	/* process DMA devices within bracket. */
> > +	addrs++;
> > +	substr = strtok(addrs, ";]");
> > +	if (!substr) {
> > +		VHOST_LOG(ERR, "No input DMA addresse\n");
> > +		ret = -1;
> > +		goto out;
> > +	}
> > +
> > +	do {
> > +		rte_strsplit(substr, strlen(substr), ptrs, 2, '@');
> > +
> > +		char *txq, *rxq;
> > +		bool is_txq;
> > +
> > +		txq = strstr(ptrs[0], "txq");
> > +		rxq = strstr(ptrs[0], "rxq");
> > +		if (txq == NULL && rxq == NULL) {
> > +			VHOST_LOG(ERR, "Illegal queue\n");
> > +			ret = -1;
> > +			goto out;
> > +		} else if (txq) {
> > +			is_txq = true;
> > +			start = txq;
> > +		} else {
> > +			is_txq = false;
> > +			start = rxq;
> > +		}
> > +
> > +		start += 3;
> > +		qid = strtol(start, &end, 0);
> > +		if (end == start) {
> > +			VHOST_LOG(ERR, "No input queue ID\n");
> > +			ret = -1;
> > +			goto out;
> > +		}
> > +
> > +		virtqueue_id = is_txq ? qid * 2 + VIRTIO_RXQ : qid * 2 +
> > +VIRTIO_TXQ;
> > +
> > +		dma_id = rte_dma_get_dev_id_by_name(ptrs[1]);
> > +		if (dma_id < 0) {
> > +			VHOST_LOG(ERR, "Fail to find DMA device %s.\n",
> ptrs[1]);
> > +			ret = -1;
> > +			goto out;
> > +		}
> > +
> > +		ret = init_dma(dma_id, dma_input->dma_ring_size);
> > +		if (ret != 0) {
> > +			VHOST_LOG(ERR, "Fail to initialize DMA %u\n",
> dma_id);
> > +			ret = -1;
> > +			break;
> > +		}
> > +
> > +		dma_input->dmas[virtqueue_id] = dma_id;
> > +
> > +		substr = strtok(NULL, ";]");
> > +	} while (substr);
> > +
> > +	for (i = 0; i < dma_count; i++) {
> > +		if (rte_vhost_async_dma_configure(configured_dmas[i], 0) <
> 0) {
> > +			VHOST_LOG(ERR, "Fail to configure DMA %u to
> vhost\n", configured_dmas[i]);
> > +			ret = -1;
> > +		}
> > +	}
> > +
> > +out:
> > +	free(input);
> > +	return ret;
> > +}
> > +
> >   static int
> >   rte_pmd_vhost_probe(struct rte_vdev_device *dev)
> >   {
> > @@ -1621,6 +2024,10 @@ rte_pmd_vhost_probe(struct rte_vdev_device
> *dev)
> >   	int legacy_ol_flags = 0;
> >   	struct rte_eth_dev *eth_dev;
> >   	const char *name = rte_vdev_device_name(dev);
> > +	struct dma_input_info dma_input;
> > +
> > +	memset(dma_input.dmas, INVALID_DMA_ID,
> sizeof(dma_input.dmas));
> > +	dma_input.dma_ring_size = DEFAULT_DMA_RING_SIZE;
> >
> >   	VHOST_LOG(INFO, "Initializing pmd_vhost for %s\n", name);
> >
> > @@ -1736,6 +2143,43 @@ rte_pmd_vhost_probe(struct rte_vdev_device
> *dev)
> >   			goto out_free;
> >   	}
> >
> > +	if (rte_kvargs_count(kvlist, ETH_VHOST_DMA_RING_SIZE) == 1) {
> > +		if (rte_kvargs_count(kvlist, ETH_VHOST_DMA_ARG) == 1) {
> > +			ret = rte_kvargs_process(kvlist,
> ETH_VHOST_DMA_RING_SIZE,
> > +					&open_int,
> &dma_input.dma_ring_size);
> > +			if (ret < 0)
> > +				goto out_free;
> > +
> > +			if (!rte_is_power_of_2(dma_input.dma_ring_size)) {
> > +				dma_input.dma_ring_size =
> rte_align32pow2(dma_input.dma_ring_size);
> > +				VHOST_LOG(INFO, "Convert dma_ring_size to
> the power of two %u\n",
> > +						dma_input.dma_ring_size);
> > +			}
> > +		} else {
> > +			VHOST_LOG(WARNING, "%s is not specified, skip to
> parse %s\n",
> > +					ETH_VHOST_DMA_ARG,
> ETH_VHOST_DMA_RING_SIZE);
> > +		}
> > +	}
> > +
> > +	if (rte_kvargs_count(kvlist, ETH_VHOST_DMA_ARG) == 1) {
> > +		if (rte_kvargs_count(kvlist, ETH_VHOST_DMA_RING_SIZE) ==
> 0)
> > +			VHOST_LOG(INFO, "Use default dma ring size %d\n",
> > +DEFAULT_DMA_RING_SIZE);
> > +
> > +		ret = rte_kvargs_process(kvlist, ETH_VHOST_DMA_ARG,
> > +					 &open_dma, &dma_input);
> > +		if (ret < 0) {
> > +			VHOST_LOG(ERR, "Failed to parse %s\n",
> ETH_VHOST_DMA_ARG);
> > +			goto out_free;
> > +		}
> > +
> > +		flags |= RTE_VHOST_USER_ASYNC_COPY;
> > +		/**
> > +		 * Don't support live migration when enable
> > +		 * DMA acceleration.
> > +		 */
> > +		disable_flags |= (1ULL << VHOST_F_LOG_ALL);
> > +	}
> > +
> >   	if (legacy_ol_flags == 0)
> >   		flags |= RTE_VHOST_USER_NET_COMPLIANT_OL_FLAGS;
> >
> > @@ -1743,7 +2187,7 @@ rte_pmd_vhost_probe(struct rte_vdev_device
> *dev)
> >   		dev->device.numa_node = rte_socket_id();
> >
> >   	ret = eth_dev_vhost_create(dev, iface_name, queues,
> > -				   dev->device.numa_node, flags,
> disable_flags);
> > +			dev->device.numa_node, flags, disable_flags,
> &dma_input);
> >   	if (ret == -1)
> >   		VHOST_LOG(ERR, "Failed to create %s\n", name);
> >
> > @@ -1787,4 +2231,6 @@ RTE_PMD_REGISTER_PARAM_STRING(net_vhost,
> >   	"postcopy-support=<0|1> "
> >   	"tso=<0|1> "
> >   	"linear-buffer=<0|1> "
> > -	"ext-buffer=<0|1>");
> > +	"ext-buffer=<0|1> "
> > +	"dma-ring-size=<int> "
> > +	"dmas=[txq0@dma_addr;rxq0@dma_addr]");
> > diff --git a/drivers/net/vhost/rte_eth_vhost.h
> > b/drivers/net/vhost/rte_eth_vhost.h
> > index 0e68b9f668..146c98803d 100644
> > --- a/drivers/net/vhost/rte_eth_vhost.h
> > +++ b/drivers/net/vhost/rte_eth_vhost.h
> > @@ -52,6 +52,21 @@ int rte_eth_vhost_get_queue_event(uint16_t port_id,
> >    */
> >   int rte_eth_vhost_get_vid_from_port_id(uint16_t port_id);
> >
> > +/**
> > + * @warning
> > + * @b EXPERIMENTAL: this API may change, or be removed, without prior
> > +notice
> > + *
> > + * By default, rte_vhost_poll_enqueue_completed() is called in Rx path.
> > + * This function enables Tx path, rather than Rx path, to poll
> > +completed
> > + * packets for vhost async enqueue operations. Note that virtio may
> > +never
> > + * receive DMA completed packets if there are no more Tx operations.
> > + *
> > + * @param enable
> > + *  True indicates Tx path to call rte_vhost_poll_enqueue_completed().
> > + */
> > +__rte_experimental
> > +void rte_eth_vhost_async_tx_poll_completed(bool enable);
> > +
> >   #ifdef __cplusplus
> >   }
> >   #endif
> > diff --git a/drivers/net/vhost/version.map
> > b/drivers/net/vhost/version.map index e42c89f1eb..0a40441227 100644
> > --- a/drivers/net/vhost/version.map
> > +++ b/drivers/net/vhost/version.map
> > @@ -6,3 +6,10 @@ DPDK_23 {
> >
> >   	local: *;
> >   };
> > +
> > +EXPERIMENTAL {
> > +	global:
> > +
> > +	# added in 22.11
> > +	rte_eth_vhost_async_tx_poll_completed;
> 
> I'm not in favor of adding driver-specific API.
> IMHO, you should just decide whether doing completion on Tx or Rx path
> and stick with it.
> 
> Doing completion on the Tx path not being reliable (i.e. if not other packets
> are sent, last enqueued packets are not completed), I guess only doing
> completion in Rx path is the right thing to do.

It's good to know your thoughts. But if we remove the driver-specific API and
put poll_enqueue_completed in Rx path, Testpmd txonly mode cannot work
with DMA accelerated enqueue, as no one will call poll_enqueue_completed.
Any thoughts?

Thanks,
Jiayu
Maxime Coquelin Oct. 25, 2022, 7:52 a.m. UTC | #5
Hi Jiayu,

On 10/25/22 04:14, Hu, Jiayu wrote:
> Hi Maxime,
> 
> Thanks for your comments. Please see replies inline.
> 
>> -----Original Message-----
>> From: Maxime Coquelin <maxime.coquelin@redhat.com>
>> Sent: Monday, October 24, 2022 5:08 PM
>> To: Wang, YuanX <yuanx.wang@intel.com>; Xia, Chenbo
>> <chenbo.xia@intel.com>
>> Cc: dev@dpdk.org; Hu, Jiayu <jiayu.hu@intel.com>; Jiang, Cheng1
>> <cheng1.jiang@intel.com>; Ma, WenwuX <wenwux.ma@intel.com>; He,
>> Xingguang <xingguang.he@intel.com>
>> Subject: Re: [PATCH v5] net/vhost: support asynchronous data path
>>
>> Hi Yuan,
>>
>> Please fix your system for the next times, your patch is dated several hours in
>> the future.
>>
>> On 10/24/22 17:14, Yuan Wang wrote:
>>> Vhost asynchronous data-path offloads packet copy from the CPU to the
>>> DMA engine. As a result, large packet copy can be accelerated by the
>>> DMA engine, and vhost can free CPU cycles for higher level
>>
>> Vhost
>>
>>> functions.
>>>
>>> In this patch, we enable asynchronous data-path for vhostpmd.
>>> Asynchronous data path is enabled per tx/rx queue, and users need to
>>> specify the DMA device used by the tx/rx queue. Each tx/rx queue only
>>> supports to use one DMA device, but one DMA device can be shared
>> among
>>> multiple tx/rx queues of different vhost PMD ports.
>>>
>>> Two PMD parameters are added:
>>> - dmas:	specify the used DMA device for a tx/rx queue.
>>> 	(Default: no queues enable asynchronous data path)
>>> - dma-ring-size: DMA ring size.
>>> 	(Default: 4096).
>>>
>>> Here is an example:
>>> --vdev
>> 'eth_vhost0,iface=./s0,dmas=[txq0@0000:00.01.0;rxq0@0000:00.01.1],dma-
>> ring-size=4096'
>>>
>>> Signed-off-by: Jiayu Hu <jiayu.hu@intel.com>
>>> Signed-off-by: Yuan Wang <yuanx.wang@intel.com>
>>> Signed-off-by: Wenwu Ma <wenwux.ma@intel.com>
>>>
>>> ---
>>> v5:
>>> - add error log of testpmd cmd
>>>
>>> v4:
>>> - add txq allow_queuing check on poll completed
>>> - unregister dma channel in destroy_device
>>> - add dma ring size minimum limit
>>> - fix serveral code style and logging issues
>>>
>>> v3:
>>> - add the API to version.map
>>>
>>> v2:
>>> - add missing file
>>> - hide async_tx_poll_completed
>>> - change default DMA ring size to 4096
>>>
>>> ---
>>>    drivers/net/vhost/meson.build     |   1 +
>>>    drivers/net/vhost/rte_eth_vhost.c | 512
>> ++++++++++++++++++++++++++++--
>>>    drivers/net/vhost/rte_eth_vhost.h |  15 +
>>>    drivers/net/vhost/version.map     |   7 +
>>>    drivers/net/vhost/vhost_testpmd.c |  67 ++++
>>>    5 files changed, 569 insertions(+), 33 deletions(-)
>>>    create mode 100644 drivers/net/vhost/vhost_testpmd.c
>>>
>>> diff --git a/drivers/net/vhost/meson.build
>>> b/drivers/net/vhost/meson.build index f481a3a4b8..22a0ab3a58 100644
>>> --- a/drivers/net/vhost/meson.build
>>> +++ b/drivers/net/vhost/meson.build
>>> @@ -9,4 +9,5 @@ endif
>>>
>>>    deps += 'vhost'
>>>    sources = files('rte_eth_vhost.c')
>>> +testpmd_sources = files('vhost_testpmd.c')
>>>    headers = files('rte_eth_vhost.h')
>>> diff --git a/drivers/net/vhost/rte_eth_vhost.c
>>> b/drivers/net/vhost/rte_eth_vhost.c
>>> index b152279fac..80cd9c8d92 100644
>>> --- a/drivers/net/vhost/rte_eth_vhost.c
>>> +++ b/drivers/net/vhost/rte_eth_vhost.c
>>> @@ -7,6 +7,7 @@
>>>    #include <pthread.h>
>>>    #include <stdbool.h>
>>>    #include <sys/epoll.h>
>>> +#include <ctype.h>
>>>
>>>    #include <rte_mbuf.h>
>>>    #include <ethdev_driver.h>
>>> @@ -18,6 +19,8 @@
>>>    #include <rte_kvargs.h>
>>>    #include <rte_vhost.h>
>>>    #include <rte_spinlock.h>
>>> +#include <rte_vhost_async.h>
>>> +#include <rte_dmadev.h>
>>>
>>>    #include "rte_eth_vhost.h"
>>>
>>> @@ -37,8 +40,15 @@ enum {VIRTIO_RXQ, VIRTIO_TXQ, VIRTIO_QNUM};
>>>    #define ETH_VHOST_LINEAR_BUF		"linear-buffer"
>>>    #define ETH_VHOST_EXT_BUF		"ext-buffer"
>>>    #define ETH_VHOST_LEGACY_OL_FLAGS	"legacy-ol-flags"
>>> +#define ETH_VHOST_DMA_ARG		"dmas"
>>> +#define ETH_VHOST_DMA_RING_SIZE		"dma-ring-size"
>>>    #define VHOST_MAX_PKT_BURST 32
>>>
>>> +#define INVALID_DMA_ID		-1
>>> +#define DEFAULT_DMA_RING_SIZE	4096
>>> +/* Minimum package size is 64, dma ring size should be greater than 32 */
>>> +#define MINIMUM_DMA_RING_SIZE	64
>>
>> Why? Is that related to Intel HW?
> 
> No, it is for TCP/UDP tests. The max TCP/UDP length is 64KB, so one packet
> needs 32 pktmbufs. If we set DMA ring size to 32, it's possible that vhost cannot
> enqueue/dequeue one packet, as there may be some control packets mixed and
> DMA ring full will cause enqueue/dequeue the packet failed. So the recommend
> minimal DMA ring size is > 32.

I guess it depends on the mbuf size, doesn't it?
I'm not against having a default value, but we need to understand the
rationale by just reading the code and not having to ask the author.

> 
> We can remove the macro, but add one comment to suggest the DMA ring
> size.
>>
>>> +
>>>    static const char *valid_arguments[] = {
>>>    	ETH_VHOST_IFACE_ARG,
>>>    	ETH_VHOST_QUEUES_ARG,
>>> @@ -49,6 +59,8 @@ static const char *valid_arguments[] = {
>>>    	ETH_VHOST_LINEAR_BUF,
>>>    	ETH_VHOST_EXT_BUF,
>>>    	ETH_VHOST_LEGACY_OL_FLAGS,
>>> +	ETH_VHOST_DMA_ARG,
>>> +	ETH_VHOST_DMA_RING_SIZE,
>>>    	NULL
>>>    };
>>>
>>> @@ -80,8 +92,39 @@ struct vhost_queue {
>>>    	struct vhost_stats stats;
>>>    	int intr_enable;
>>>    	rte_spinlock_t intr_lock;
>>> +
>>> +	/* Flag of enabling async data path */
>>> +	bool async_register;
>>> +	/* DMA device ID */
>>> +	int16_t dma_id;
>>> +	/**
>>> +	 * For a Rx queue, "txq" points to its peer Tx queue.
>>> +	 * For a Tx queue, "txq" is never used.
>>> +	 */
>>> +	struct vhost_queue *txq;
>>> +	/* Array to keep DMA completed packets */
>>> +	struct rte_mbuf *cmpl_pkts[VHOST_MAX_PKT_BURST];
>>>    };
>>>
>>> +struct dma_input_info {
>>> +	int16_t dmas[RTE_MAX_QUEUES_PER_PORT * 2];
>>> +	uint16_t dma_ring_size;
>>> +};
>>> +
>>> +static int16_t configured_dmas[RTE_DMADEV_DEFAULT_MAX];
>>> +static int dma_count;
>>> +
>>> +/**
>>> + * By default, its Rx path to call rte_vhost_poll_enqueue_completed() for
>> enqueue operations.
>>> + * However, Rx function is never been called in testpmd "txonly"
>>> +mode, thus causing virtio
>>> + * cannot receive DMA completed packets. To make txonly mode work
>>> +correctly, we provide a
>>> + * command in testpmd to call rte_vhost_poll_enqueue_completed() in Tx
>> path.
>>> + *
>>> + * When set async_tx_poll_completed to true, Tx path calls
>>> +rte_vhost_poll_enqueue_completed();
>>> + * otherwise, Rx path calls it.
>>> + */
>>> +bool async_tx_poll_completed;
>>> +
>>>    struct pmd_internal {
>>>    	rte_atomic32_t dev_attached;
>>>    	char *iface_name;
>>> @@ -94,6 +137,10 @@ struct pmd_internal {
>>>    	bool vlan_strip;
>>>    	bool rx_sw_csum;
>>>    	bool tx_sw_csum;
>>> +	struct {
>>> +		int16_t dma_id;
>>> +		bool async_register;
>>> +	} queue_dmas[RTE_MAX_QUEUES_PER_PORT * 2];
>>>    };
>>>
>>>    struct internal_list {
>>> @@ -124,6 +171,17 @@ struct rte_vhost_vring_state {
>>>
>>>    static struct rte_vhost_vring_state *vring_states[RTE_MAX_ETHPORTS];
>>>
>>> +static bool
>>> +dma_is_configured(int16_t dma_id)
>>> +{
>>> +	int i;
>>> +
>>> +	for (i = 0; i < dma_count; i++)
>>> +		if (configured_dmas[i] == dma_id)
>>> +			return true;
>>> +	return false;
>>> +}
>>> +
>>>    static int
>>>    vhost_dev_xstats_reset(struct rte_eth_dev *dev)
>>>    {
>>> @@ -396,15 +454,27 @@ vhost_dev_rx_sw_csum(struct rte_mbuf *mbuf)
>>>    	mbuf->ol_flags |= RTE_MBUF_F_RX_L4_CKSUM_GOOD;
>>>    }
>>>
>>> +static inline void
>>> +vhost_tx_free_completed(int vid, uint16_t virtqueue_id, int16_t dma_id,
>>> +		struct rte_mbuf **pkts, uint16_t count) {
>>> +	uint16_t i, ret;
>>> +
>>> +	ret = rte_vhost_poll_enqueue_completed(vid, virtqueue_id, pkts,
>> count, dma_id, 0);
>>> +	for (i = 0; likely(i < ret); i++)
>>> +		rte_pktmbuf_free(pkts[i]);
>>> +}
>>> +
>>>    static uint16_t
>>>    eth_vhost_rx(void *q, struct rte_mbuf **bufs, uint16_t nb_bufs)
>>>    {
>>>    	struct vhost_queue *r = q;
>>>    	uint16_t i, nb_rx = 0;
>>>    	uint16_t nb_receive = nb_bufs;
>>> +	uint16_t nb_pkts, num;
>>>
>>>    	if (unlikely(rte_atomic32_read(&r->allow_queuing) == 0))
>>> -		return 0;
>>> +		goto tx_poll;
>>>
>>>    	rte_atomic32_set(&r->while_queuing, 1);
>>>
>>> @@ -412,19 +482,32 @@ eth_vhost_rx(void *q, struct rte_mbuf **bufs,
>> uint16_t nb_bufs)
>>>    		goto out;
>>>
>>>    	/* Dequeue packets from guest TX queue */
>>> -	while (nb_receive) {
>>> -		uint16_t nb_pkts;
>>> -		uint16_t num = (uint16_t)RTE_MIN(nb_receive,
>>> -						 VHOST_MAX_PKT_BURST);
>>> -
>>> -		nb_pkts = rte_vhost_dequeue_burst(r->vid, r->virtqueue_id,
>>> -						  r->mb_pool, &bufs[nb_rx],
>>> -						  num);
>>> -
>>> -		nb_rx += nb_pkts;
>>> -		nb_receive -= nb_pkts;
>>> -		if (nb_pkts < num)
>>> -			break;
>>> +	if (!r->async_register) {
>>> +		while (nb_receive) {
>>> +			num = (uint16_t)RTE_MIN(nb_receive,
>> VHOST_MAX_PKT_BURST);
>>> +			nb_pkts = rte_vhost_dequeue_burst(r->vid, r-
>>> virtqueue_id,
>>> +						r->mb_pool, &bufs[nb_rx],
>>> +						num);
>>> +
>>> +			nb_rx += nb_pkts;
>>> +			nb_receive -= nb_pkts;
>>> +			if (nb_pkts < num)
>>> +				break;
>>> +		}
>>> +	} else {
>>> +		int nr_inflight;
>>> +
>>> +		while (nb_receive) {
>>> +			num = (uint16_t)RTE_MIN(nb_receive,
>> VHOST_MAX_PKT_BURST);
>>> +			nb_pkts = rte_vhost_async_try_dequeue_burst(r-
>>> vid, r->virtqueue_id,
>>> +						r->mb_pool, &bufs[nb_rx],
>> num, &nr_inflight,
>>> +						r->dma_id, 0);
>>> +
>>> +			nb_rx += nb_pkts;
>>> +			nb_receive -= nb_pkts;
>>> +			if (nb_pkts < num)
>>> +				break;
>>> +		}
>>>    	}
>>>
>>>    	r->stats.pkts += nb_rx;
>>> @@ -445,6 +528,17 @@ eth_vhost_rx(void *q, struct rte_mbuf **bufs,
>> uint16_t nb_bufs)
>>>    out:
>>>    	rte_atomic32_set(&r->while_queuing, 0);
>>>
>>> +tx_poll:
>>> +	/**
>>> +	 * Poll and free completed packets for the virtqueue of Tx queue.
>>> +	 * Note that we access Tx queue's virtqueue, which is protected
>>> +	 * by vring lock.
>>> +	 */
>>> +	if (r->txq->async_register && !async_tx_poll_completed &&
>>> +			rte_atomic32_read(&r->txq->allow_queuing) == 1)
>>> +		vhost_tx_free_completed(r->vid, r->txq->virtqueue_id, r-
>>> txq->dma_id,
>>> +				r->cmpl_pkts, VHOST_MAX_PKT_BURST);
>>> +
>>>    	return nb_rx;
>>>    }
>>>
>>> @@ -456,6 +550,7 @@ eth_vhost_tx(void *q, struct rte_mbuf **bufs,
>> uint16_t nb_bufs)
>>>    	uint16_t nb_send = 0;
>>>    	uint64_t nb_bytes = 0;
>>>    	uint64_t nb_missed = 0;
>>> +	uint16_t nb_pkts, num;
>>>
>>>    	if (unlikely(rte_atomic32_read(&r->allow_queuing) == 0))
>>>    		return 0;
>>> @@ -486,31 +581,49 @@ eth_vhost_tx(void *q, struct rte_mbuf **bufs,
>> uint16_t nb_bufs)
>>>    	}
>>>
>>>    	/* Enqueue packets to guest RX queue */
>>> -	while (nb_send) {
>>> -		uint16_t nb_pkts;
>>> -		uint16_t num = (uint16_t)RTE_MIN(nb_send,
>>> -						 VHOST_MAX_PKT_BURST);
>>> +	if (!r->async_register) {
>>> +		while (nb_send) {
>>> +			num = (uint16_t)RTE_MIN(nb_send,
>> VHOST_MAX_PKT_BURST);
>>> +			nb_pkts = rte_vhost_enqueue_burst(r->vid, r-
>>> virtqueue_id,
>>> +						&bufs[nb_tx], num);
>>> +
>>> +			nb_tx += nb_pkts;
>>> +			nb_send -= nb_pkts;
>>> +			if (nb_pkts < num)
>>> +				break;
>>> +		}
>>>
>>> -		nb_pkts = rte_vhost_enqueue_burst(r->vid, r->virtqueue_id,
>>> -						  &bufs[nb_tx], num);
>>> +		for (i = 0; likely(i < nb_tx); i++) {
>>> +			nb_bytes += bufs[i]->pkt_len;
>>> +			rte_pktmbuf_free(bufs[i]);
>>> +		}
>>>
>>> -		nb_tx += nb_pkts;
>>> -		nb_send -= nb_pkts;
>>> -		if (nb_pkts < num)
>>> -			break;
>>> -	}
>>> +	} else {
>>> +		while (nb_send) {
>>> +			num = (uint16_t)RTE_MIN(nb_send,
>> VHOST_MAX_PKT_BURST);
>>> +			nb_pkts = rte_vhost_submit_enqueue_burst(r->vid,
>> r->virtqueue_id,
>>> +							&bufs[nb_tx], num, r-
>>> dma_id, 0);
>>> +
>>> +			nb_tx += nb_pkts;
>>> +			nb_send -= nb_pkts;
>>> +			if (nb_pkts < num)
>>> +				break;
>>> +		}
>>>
>>> -	for (i = 0; likely(i < nb_tx); i++)
>>> -		nb_bytes += bufs[i]->pkt_len;
>>> +		for (i = 0; likely(i < nb_tx); i++)
>>> +			nb_bytes += bufs[i]->pkt_len;
>>>
>>> -	nb_missed = nb_bufs - nb_tx;
>>> +		if (unlikely(async_tx_poll_completed)) {
>>> +			vhost_tx_free_completed(r->vid, r->virtqueue_id, r-
>>> dma_id, r->cmpl_pkts,
>>> +					VHOST_MAX_PKT_BURST);
>>> +		}
>>> +	}
>>>
>>> +	nb_missed = nb_bufs - nb_tx;
>>>    	r->stats.pkts += nb_tx;
>>>    	r->stats.bytes += nb_bytes;
>>>    	r->stats.missed_pkts += nb_missed;
>>>
>>> -	for (i = 0; likely(i < nb_tx); i++)
>>> -		rte_pktmbuf_free(bufs[i]);
>>>    out:
>>>    	rte_atomic32_set(&r->while_queuing, 0);
>>>
>>> @@ -798,6 +911,8 @@ queue_setup(struct rte_eth_dev *eth_dev, struct
>> pmd_internal *internal)
>>>    		vq->vid = internal->vid;
>>>    		vq->internal = internal;
>>>    		vq->port = eth_dev->data->port_id;
>>> +		if (i < eth_dev->data->nb_tx_queues)
>>> +			vq->txq = eth_dev->data->tx_queues[i];
>>>    	}
>>>    	for (i = 0; i < eth_dev->data->nb_tx_queues; i++) {
>>>    		vq = eth_dev->data->tx_queues[i];
>>> @@ -878,6 +993,30 @@ new_device(int vid)
>>>    	return 0;
>>>    }
>>>
>>> +static inline void
>>> +async_clear_virtqueue(int vid, uint16_t virtqueue_id, int16_t dma_id)
>>> +{
>>> +	struct rte_mbuf *pkts[VHOST_MAX_PKT_BURST];
>>> +	uint16_t i, ret, nr_done = 0;
>>> +
>>> +	if (vid == -1)
>>> +		return;
>>> +
>>> +	while (rte_vhost_async_get_inflight(vid, virtqueue_id) > 0) {
>>> +		ret = rte_vhost_clear_queue(vid, virtqueue_id, pkts,
>> VHOST_MAX_PKT_BURST, dma_id,
>>> +				0);
>>> +		for (i = 0; i < ret ; i++)
>>> +			rte_pktmbuf_free(pkts[i]);
>>> +
>>> +		nr_done += ret;
>>> +	}
>>> +	VHOST_LOG(INFO, "Completed %u pkts for vid-%u vring-%u\n",
>> nr_done,
>>> +vid, virtqueue_id);
>>> +
>>> +	if (rte_vhost_async_channel_unregister(vid, virtqueue_id))
>>> +		VHOST_LOG(ERR, "Failed to unregister async for vid-%u
>> vring-%u\n", vid,
>>> +				virtqueue_id);
>>> +}
>>> +
>>>    static void
>>>    destroy_device(int vid)
>>>    {
>>> @@ -908,13 +1047,27 @@ destroy_device(int vid)
>>>    			vq = eth_dev->data->rx_queues[i];
>>>    			if (!vq)
>>>    				continue;
>>> +			if (vq->async_register) {
>>> +				async_clear_virtqueue(vq->vid, vq-
>>> virtqueue_id,
>>> +							vq->dma_id);
>>> +				vq->async_register = false;
>>> +				internal->queue_dmas[vq-
>>> virtqueue_id].async_register = false;
>>> +			}
>>>    			vq->vid = -1;
>>> +
>>>    		}
>>>    		for (i = 0; i < eth_dev->data->nb_tx_queues; i++) {
>>>    			vq = eth_dev->data->tx_queues[i];
>>>    			if (!vq)
>>>    				continue;
>>> +			if (vq->async_register) {
>>> +				async_clear_virtqueue(vq->vid, vq-
>>> virtqueue_id,
>>> +							vq->dma_id);
>>> +				vq->async_register = false;
>>> +				internal->queue_dmas[vq-
>>> virtqueue_id].async_register = false;
>>> +			}
>>>    			vq->vid = -1;
>>> +
>>>    		}
>>>    	}
>>>
>>> @@ -983,6 +1136,9 @@ vring_state_changed(int vid, uint16_t vring, int
>> enable)
>>>    	struct rte_vhost_vring_state *state;
>>>    	struct rte_eth_dev *eth_dev;
>>>    	struct internal_list *list;
>>> +	struct vhost_queue *queue;
>>> +	struct pmd_internal *internal;
>>> +	int qid;
>>>    	char ifname[PATH_MAX];
>>>
>>>    	rte_vhost_get_ifname(vid, ifname, sizeof(ifname)); @@ -1011,6
>>> +1167,65 @@ vring_state_changed(int vid, uint16_t vring, int enable)
>>>
>>>    	update_queuing_status(eth_dev, false);
>>>
>>> +	qid = vring / VIRTIO_QNUM;
>>> +	if (vring % VIRTIO_QNUM == VIRTIO_RXQ)
>>> +		queue = eth_dev->data->tx_queues[qid];
>>> +	else
>>> +		queue = eth_dev->data->rx_queues[qid];
>>> +
>>> +	if (!queue)
>>> +		goto skip;
>>> +
>>> +	internal = eth_dev->data->dev_private;
>>> +
>>> +	/* Register async data path for the queue assigned valid DMA device
>> */
>>> +	if (internal->queue_dmas[queue->virtqueue_id].dma_id ==
>> INVALID_DMA_ID)
>>> +		goto skip;
>>> +
>>> +	if (enable && !queue->async_register) {
>>> +		if (rte_vhost_async_channel_register_thread_unsafe(vid,
>> vring)) {
>>> +			VHOST_LOG(ERR, "Failed to register async for vid-%u
>> vring-%u!\n", vid,
>>> +					vring);
>>> +			return -1;
>>> +		}
>>> +
>>> +		queue->async_register = true;
>>> +		internal->queue_dmas[vring].async_register = true;
>>> +
>>> +		VHOST_LOG(INFO, "Succeed to register async for vid-%u
>> vring-%u\n", vid, vring);
>>> +	}
>>> +
>>> +	if (!enable && queue->async_register) {
>>> +		struct rte_mbuf *pkts[VHOST_MAX_PKT_BURST];
>>> +		uint16_t ret, i, nr_done = 0;
>>> +		uint16_t dma_id = queue->dma_id;
>>> +
>>> +		while (rte_vhost_async_get_inflight_thread_unsafe(vid,
>> vring) > 0) {
>>> +			ret = rte_vhost_clear_queue_thread_unsafe(vid,
>> vring, pkts,
>>> +					VHOST_MAX_PKT_BURST, dma_id, 0);
>>> +
>>> +			for (i = 0; i < ret ; i++)
>>> +				rte_pktmbuf_free(pkts[i]);
>>> +
>>> +			nr_done += ret;
>>> +		}
>>> +
>>> +		VHOST_LOG(INFO, "Completed %u in-flight pkts for vid-%u
>> vring-%u\n", nr_done, vid,
>>> +				vring);
>>> +
>>> +		if (rte_vhost_async_channel_unregister_thread_unsafe(vid,
>> vring)) {
>>> +			VHOST_LOG(ERR, "Failed to unregister async for vid-
>> %u vring-%u\n", vid,
>>> +					vring);
>>> +			return -1;
>>> +		}
>>> +
>>> +		queue->async_register = false;
>>> +		internal->queue_dmas[vring].async_register = false;
>>> +
>>> +		VHOST_LOG(INFO, "Succeed to unregister async for vid-%u
>> vring-%u\n", vid, vring);
>>> +	}
>>> +
>>> +skip:
>>>    	VHOST_LOG(INFO, "vring%u is %s\n",
>>>    			vring, enable ? "enabled" : "disabled");
>>>
>>> @@ -1159,6 +1374,12 @@ rte_eth_vhost_get_vid_from_port_id(uint16_t
>> port_id)
>>>    	return vid;
>>>    }
>>>
>>> +void
>>> +rte_eth_vhost_async_tx_poll_completed(bool enable) {
>>> +	async_tx_poll_completed = enable;
>>> +}
>>> +
>>>    static int
>>>    eth_dev_configure(struct rte_eth_dev *dev)
>>>    {
>>> @@ -1220,6 +1441,7 @@ eth_dev_close(struct rte_eth_dev *dev)
>>>    {
>>>    	struct pmd_internal *internal;
>>>    	struct internal_list *list;
>>> +	struct vhost_queue *queue;
>>>    	unsigned int i, ret;
>>>
>>>    	if (rte_eal_process_type() != RTE_PROC_PRIMARY) @@ -1233,6
>> +1455,25
>>> @@ eth_dev_close(struct rte_eth_dev *dev)
>>>
>>>    	list = find_internal_resource(internal->iface_name);
>>>    	if (list) {
>>> +		/* Make sure all in-flight packets are completed before
>> destroy vhost */
>>> +		if (dev->data->rx_queues) {
>>> +			for (i = 0; i < dev->data->nb_rx_queues; i++) {
>>> +				queue = dev->data->rx_queues[i];
>>> +				if (queue->async_register)
>>> +					async_clear_virtqueue(queue->vid,
>> queue->virtqueue_id,
>>> +							queue->dma_id);
>>> +			}
>>> +		}
>>> +
>>> +		if (dev->data->tx_queues) {
>>> +			for (i = 0; i < dev->data->nb_tx_queues; i++) {
>>> +				queue = dev->data->tx_queues[i];
>>> +				if (queue->async_register)
>>> +					async_clear_virtqueue(queue->vid,
>> queue->virtqueue_id,
>>> +							queue->dma_id);
>>> +			}
>>> +		}
>>> +
>>>    		rte_vhost_driver_unregister(internal->iface_name);
>>>    		pthread_mutex_lock(&internal_list_lock);
>>>    		TAILQ_REMOVE(&internal_list, list, next); @@ -1267,6
>> +1508,7 @@
>>> eth_rx_queue_setup(struct rte_eth_dev *dev, uint16_t rx_queue_id,
>>>    		   struct rte_mempool *mb_pool)
>>>    {
>>>    	struct vhost_queue *vq;
>>> +	struct pmd_internal *internal = dev->data->dev_private;
>>>
>>>    	vq = rte_zmalloc_socket(NULL, sizeof(struct vhost_queue),
>>>    			RTE_CACHE_LINE_SIZE, socket_id);
>>> @@ -1277,6 +1519,8 @@ eth_rx_queue_setup(struct rte_eth_dev *dev,
>>> uint16_t rx_queue_id,
>>>
>>>    	vq->mb_pool = mb_pool;
>>>    	vq->virtqueue_id = rx_queue_id * VIRTIO_QNUM + VIRTIO_TXQ;
>>> +	vq->async_register = internal->queue_dmas[vq-
>>> virtqueue_id].async_register;
>>> +	vq->dma_id = internal->queue_dmas[vq->virtqueue_id].dma_id;
>>>    	rte_spinlock_init(&vq->intr_lock);
>>>    	dev->data->rx_queues[rx_queue_id] = vq;
>>>
>>> @@ -1290,6 +1534,7 @@ eth_tx_queue_setup(struct rte_eth_dev *dev,
>> uint16_t tx_queue_id,
>>>    		   const struct rte_eth_txconf *tx_conf __rte_unused)
>>>    {
>>>    	struct vhost_queue *vq;
>>> +	struct pmd_internal *internal = dev->data->dev_private;
>>>
>>>    	vq = rte_zmalloc_socket(NULL, sizeof(struct vhost_queue),
>>>    			RTE_CACHE_LINE_SIZE, socket_id);
>>> @@ -1299,6 +1544,8 @@ eth_tx_queue_setup(struct rte_eth_dev *dev,
>> uint16_t tx_queue_id,
>>>    	}
>>>
>>>    	vq->virtqueue_id = tx_queue_id * VIRTIO_QNUM + VIRTIO_RXQ;
>>> +	vq->async_register = internal->queue_dmas[vq-
>>> virtqueue_id].async_register;
>>> +	vq->dma_id = internal->queue_dmas[vq->virtqueue_id].dma_id;
>>>    	rte_spinlock_init(&vq->intr_lock);
>>>    	dev->data->tx_queues[tx_queue_id] = vq;
>>>
>>> @@ -1509,13 +1756,14 @@ static const struct eth_dev_ops ops = {
>>>    static int
>>>    eth_dev_vhost_create(struct rte_vdev_device *dev, char *iface_name,
>>>    	int16_t queues, const unsigned int numa_node, uint64_t flags,
>>> -	uint64_t disable_flags)
>>> +	uint64_t disable_flags, struct dma_input_info *dma_input)
>>>    {
>>>    	const char *name = rte_vdev_device_name(dev);
>>>    	struct rte_eth_dev_data *data;
>>>    	struct pmd_internal *internal = NULL;
>>>    	struct rte_eth_dev *eth_dev = NULL;
>>>    	struct rte_ether_addr *eth_addr = NULL;
>>> +	int i;
>>>
>>>    	VHOST_LOG(INFO, "Creating VHOST-USER backend on numa
>> socket %u\n",
>>>    		numa_node);
>>> @@ -1564,6 +1812,12 @@ eth_dev_vhost_create(struct rte_vdev_device
>> *dev, char *iface_name,
>>>    	eth_dev->rx_pkt_burst = eth_vhost_rx;
>>>    	eth_dev->tx_pkt_burst = eth_vhost_tx;
>>>
>>> +	for (i = 0; i < RTE_MAX_QUEUES_PER_PORT * 2; i++) {
>>> +		/* Invalid DMA ID indicates the queue does not want to
>> enable async data path */
>>> +		internal->queue_dmas[i].dma_id = dma_input->dmas[i];
>>> +		internal->queue_dmas[i].async_register = false;
>>> +	}
>>> +
>>>    	rte_eth_dev_probing_finish(eth_dev);
>>>    	return 0;
>>>
>>> @@ -1603,6 +1857,155 @@ open_int(const char *key __rte_unused, const
>> char *value, void *extra_args)
>>>    	return 0;
>>>    }
>>>
>>> +static int
>>> +init_dma(int16_t dma_id, uint16_t ring_size) {
>>> +	struct rte_dma_info info;
>>> +	struct rte_dma_conf dev_config = { .nb_vchans = 1 };
>>> +	struct rte_dma_vchan_conf qconf = {
>>> +		.direction = RTE_DMA_DIR_MEM_TO_MEM,
>>> +	};
>>> +	int ret = 0;
>>> +
>>> +	if (dma_is_configured(dma_id))
>>> +		goto out;
>>> +
>>> +	if (rte_dma_info_get(dma_id, &info) != 0) {
>>> +		VHOST_LOG(ERR, "dma %u get info failed\n", dma_id);
>>> +		ret = -1;
>>> +		goto out;
>>> +	}
>>> +
>>> +	if (info.max_vchans < 1) {
>>> +		VHOST_LOG(ERR, "No channels available on dma %d\n",
>> dma_id);
>>> +		ret = -1;
>>> +		goto out;
>>> +	}
>>> +
>>> +	if (rte_dma_configure(dma_id, &dev_config) != 0) {
>>> +		VHOST_LOG(ERR, "dma %u configure failed\n", dma_id);
>>> +		ret = -1;
>>> +		goto out;
>>> +	}
>>> +
>>> +	rte_dma_info_get(dma_id, &info);
>>> +	if (info.nb_vchans != 1) {
>>> +		VHOST_LOG(ERR, "dma %u has no queues\n", dma_id);
>>> +		ret = -1;
>>> +		goto out;
>>> +	}
>>> +
>>> +	ring_size = RTE_MAX(ring_size, MINIMUM_DMA_RING_SIZE);
>>> +	ring_size = RTE_MAX(ring_size, info.min_desc);
>>> +	qconf.nb_desc = RTE_MIN(ring_size, info.max_desc);
>>> +	if (rte_dma_vchan_setup(dma_id, 0, &qconf) != 0) {
>>> +		VHOST_LOG(ERR, "dma %u queue setup failed\n", dma_id);
>>> +		ret = -1;
>>> +		goto out;
>>> +	}
>>> +
>>> +	if (rte_dma_start(dma_id) != 0) {
>>> +		VHOST_LOG(ERR, "dma %u start failed\n", dma_id);
>>> +		ret = -1;
>>> +		goto out;
>>> +	}
>>> +
>>> +	configured_dmas[dma_count++] = dma_id;
>>> +
>>> +out:
>>> +	return ret;
>>> +}
>>> +
>>> +static int
>>> +open_dma(const char *key __rte_unused, const char *value, void
>>> +*extra_args) {
>>> +	struct dma_input_info *dma_input = extra_args;
>>> +	char *input = strndup(value, strlen(value) + 1);
>>> +	char *addrs = input;
>>> +	char *ptrs[2];
>>> +	char *start, *end, *substr;
>>> +	uint16_t qid, virtqueue_id;
>>> +	int16_t dma_id;
>>> +	int i, ret = 0;
>>> +
>>> +	while (isblank(*addrs))
>>> +		addrs++;
>>> +	if (*addrs == '\0') {
>>> +		VHOST_LOG(ERR, "No input DMA addresses\n");
>>> +		ret = -1;
>>> +		goto out;
>>> +	}
>>> +
>>> +	/* process DMA devices within bracket. */
>>> +	addrs++;
>>> +	substr = strtok(addrs, ";]");
>>> +	if (!substr) {
>>> +		VHOST_LOG(ERR, "No input DMA addresse\n");
>>> +		ret = -1;
>>> +		goto out;
>>> +	}
>>> +
>>> +	do {
>>> +		rte_strsplit(substr, strlen(substr), ptrs, 2, '@');
>>> +
>>> +		char *txq, *rxq;
>>> +		bool is_txq;
>>> +
>>> +		txq = strstr(ptrs[0], "txq");
>>> +		rxq = strstr(ptrs[0], "rxq");
>>> +		if (txq == NULL && rxq == NULL) {
>>> +			VHOST_LOG(ERR, "Illegal queue\n");
>>> +			ret = -1;
>>> +			goto out;
>>> +		} else if (txq) {
>>> +			is_txq = true;
>>> +			start = txq;
>>> +		} else {
>>> +			is_txq = false;
>>> +			start = rxq;
>>> +		}
>>> +
>>> +		start += 3;
>>> +		qid = strtol(start, &end, 0);
>>> +		if (end == start) {
>>> +			VHOST_LOG(ERR, "No input queue ID\n");
>>> +			ret = -1;
>>> +			goto out;
>>> +		}
>>> +
>>> +		virtqueue_id = is_txq ? qid * 2 + VIRTIO_RXQ : qid * 2 +
>>> +VIRTIO_TXQ;
>>> +
>>> +		dma_id = rte_dma_get_dev_id_by_name(ptrs[1]);
>>> +		if (dma_id < 0) {
>>> +			VHOST_LOG(ERR, "Fail to find DMA device %s.\n",
>> ptrs[1]);
>>> +			ret = -1;
>>> +			goto out;
>>> +		}
>>> +
>>> +		ret = init_dma(dma_id, dma_input->dma_ring_size);
>>> +		if (ret != 0) {
>>> +			VHOST_LOG(ERR, "Fail to initialize DMA %u\n",
>> dma_id);
>>> +			ret = -1;
>>> +			break;
>>> +		}
>>> +
>>> +		dma_input->dmas[virtqueue_id] = dma_id;
>>> +
>>> +		substr = strtok(NULL, ";]");
>>> +	} while (substr);
>>> +
>>> +	for (i = 0; i < dma_count; i++) {
>>> +		if (rte_vhost_async_dma_configure(configured_dmas[i], 0) <
>> 0) {
>>> +			VHOST_LOG(ERR, "Fail to configure DMA %u to
>> vhost\n", configured_dmas[i]);
>>> +			ret = -1;
>>> +		}
>>> +	}
>>> +
>>> +out:
>>> +	free(input);
>>> +	return ret;
>>> +}
>>> +
>>>    static int
>>>    rte_pmd_vhost_probe(struct rte_vdev_device *dev)
>>>    {
>>> @@ -1621,6 +2024,10 @@ rte_pmd_vhost_probe(struct rte_vdev_device
>> *dev)
>>>    	int legacy_ol_flags = 0;
>>>    	struct rte_eth_dev *eth_dev;
>>>    	const char *name = rte_vdev_device_name(dev);
>>> +	struct dma_input_info dma_input;
>>> +
>>> +	memset(dma_input.dmas, INVALID_DMA_ID,
>> sizeof(dma_input.dmas));
>>> +	dma_input.dma_ring_size = DEFAULT_DMA_RING_SIZE;
>>>
>>>    	VHOST_LOG(INFO, "Initializing pmd_vhost for %s\n", name);
>>>
>>> @@ -1736,6 +2143,43 @@ rte_pmd_vhost_probe(struct rte_vdev_device
>> *dev)
>>>    			goto out_free;
>>>    	}
>>>
>>> +	if (rte_kvargs_count(kvlist, ETH_VHOST_DMA_RING_SIZE) == 1) {
>>> +		if (rte_kvargs_count(kvlist, ETH_VHOST_DMA_ARG) == 1) {
>>> +			ret = rte_kvargs_process(kvlist,
>> ETH_VHOST_DMA_RING_SIZE,
>>> +					&open_int,
>> &dma_input.dma_ring_size);
>>> +			if (ret < 0)
>>> +				goto out_free;
>>> +
>>> +			if (!rte_is_power_of_2(dma_input.dma_ring_size)) {
>>> +				dma_input.dma_ring_size =
>> rte_align32pow2(dma_input.dma_ring_size);
>>> +				VHOST_LOG(INFO, "Convert dma_ring_size to
>> the power of two %u\n",
>>> +						dma_input.dma_ring_size);
>>> +			}
>>> +		} else {
>>> +			VHOST_LOG(WARNING, "%s is not specified, skip to
>> parse %s\n",
>>> +					ETH_VHOST_DMA_ARG,
>> ETH_VHOST_DMA_RING_SIZE);
>>> +		}
>>> +	}
>>> +
>>> +	if (rte_kvargs_count(kvlist, ETH_VHOST_DMA_ARG) == 1) {
>>> +		if (rte_kvargs_count(kvlist, ETH_VHOST_DMA_RING_SIZE) ==
>> 0)
>>> +			VHOST_LOG(INFO, "Use default dma ring size %d\n",
>>> +DEFAULT_DMA_RING_SIZE);
>>> +
>>> +		ret = rte_kvargs_process(kvlist, ETH_VHOST_DMA_ARG,
>>> +					 &open_dma, &dma_input);
>>> +		if (ret < 0) {
>>> +			VHOST_LOG(ERR, "Failed to parse %s\n",
>> ETH_VHOST_DMA_ARG);
>>> +			goto out_free;
>>> +		}
>>> +
>>> +		flags |= RTE_VHOST_USER_ASYNC_COPY;
>>> +		/**
>>> +		 * Don't support live migration when enable
>>> +		 * DMA acceleration.
>>> +		 */
>>> +		disable_flags |= (1ULL << VHOST_F_LOG_ALL);
>>> +	}
>>> +
>>>    	if (legacy_ol_flags == 0)
>>>    		flags |= RTE_VHOST_USER_NET_COMPLIANT_OL_FLAGS;
>>>
>>> @@ -1743,7 +2187,7 @@ rte_pmd_vhost_probe(struct rte_vdev_device
>> *dev)
>>>    		dev->device.numa_node = rte_socket_id();
>>>
>>>    	ret = eth_dev_vhost_create(dev, iface_name, queues,
>>> -				   dev->device.numa_node, flags,
>> disable_flags);
>>> +			dev->device.numa_node, flags, disable_flags,
>> &dma_input);
>>>    	if (ret == -1)
>>>    		VHOST_LOG(ERR, "Failed to create %s\n", name);
>>>
>>> @@ -1787,4 +2231,6 @@ RTE_PMD_REGISTER_PARAM_STRING(net_vhost,
>>>    	"postcopy-support=<0|1> "
>>>    	"tso=<0|1> "
>>>    	"linear-buffer=<0|1> "
>>> -	"ext-buffer=<0|1>");
>>> +	"ext-buffer=<0|1> "
>>> +	"dma-ring-size=<int> "
>>> +	"dmas=[txq0@dma_addr;rxq0@dma_addr]");
>>> diff --git a/drivers/net/vhost/rte_eth_vhost.h
>>> b/drivers/net/vhost/rte_eth_vhost.h
>>> index 0e68b9f668..146c98803d 100644
>>> --- a/drivers/net/vhost/rte_eth_vhost.h
>>> +++ b/drivers/net/vhost/rte_eth_vhost.h
>>> @@ -52,6 +52,21 @@ int rte_eth_vhost_get_queue_event(uint16_t port_id,
>>>     */
>>>    int rte_eth_vhost_get_vid_from_port_id(uint16_t port_id);
>>>
>>> +/**
>>> + * @warning
>>> + * @b EXPERIMENTAL: this API may change, or be removed, without prior
>>> +notice
>>> + *
>>> + * By default, rte_vhost_poll_enqueue_completed() is called in Rx path.
>>> + * This function enables Tx path, rather than Rx path, to poll
>>> +completed
>>> + * packets for vhost async enqueue operations. Note that virtio may
>>> +never
>>> + * receive DMA completed packets if there are no more Tx operations.
>>> + *
>>> + * @param enable
>>> + *  True indicates Tx path to call rte_vhost_poll_enqueue_completed().
>>> + */
>>> +__rte_experimental
>>> +void rte_eth_vhost_async_tx_poll_completed(bool enable);
>>> +
>>>    #ifdef __cplusplus
>>>    }
>>>    #endif
>>> diff --git a/drivers/net/vhost/version.map
>>> b/drivers/net/vhost/version.map index e42c89f1eb..0a40441227 100644
>>> --- a/drivers/net/vhost/version.map
>>> +++ b/drivers/net/vhost/version.map
>>> @@ -6,3 +6,10 @@ DPDK_23 {
>>>
>>>    	local: *;
>>>    };
>>> +
>>> +EXPERIMENTAL {
>>> +	global:
>>> +
>>> +	# added in 22.11
>>> +	rte_eth_vhost_async_tx_poll_completed;
>>
>> I'm not in favor of adding driver-specific API.
>> IMHO, you should just decide whether doing completion on Tx or Rx path
>> and stick with it.
>>
>> Doing completion on the Tx path not being reliable (i.e. if not other packets
>> are sent, last enqueued packets are not completed), I guess only doing
>> completion in Rx path is the right thing to do.
> 
> It's good to know your thoughts. But if we remove the driver-specific API and
> put poll_enqueue_completed in Rx path, Testpmd txonly mode cannot work
> with DMA accelerated enqueue, as no one will call poll_enqueue_completed.
> Any thoughts?

I think it proves the async feature is not usable as it is implemented
today.

Expecting the user to know he has to select or change at runtime the tx
completion mode for the feature to just work (not only a performance
tuning) is not acceptable IMHO.

To summarize:
  - By default, Tx completion are done by the Rx path so txonly mode is
not working (and nothing will notify the user).
  - If user switch to Tx completion are done by the Tx path, last packet
will never be completed.

It may work for benchmark, but it is not usable in real-life.
I think that for Vhost PMD, the Virtio completions should either be
performed by DMA engine or by a dedicated thread.

Regards,
Maxime

> 
> Thanks,
> Jiayu
Hu, Jiayu Oct. 25, 2022, 9:15 a.m. UTC | #6
Hi Maxime,

> -----Original Message-----
> From: Maxime Coquelin <maxime.coquelin@redhat.com>
> Sent: Tuesday, October 25, 2022 3:52 PM
> To: Hu, Jiayu <jiayu.hu@intel.com>; Wang, YuanX <yuanx.wang@intel.com>;
> Xia, Chenbo <chenbo.xia@intel.com>
> Cc: dev@dpdk.org; Jiang, Cheng1 <cheng1.jiang@intel.com>; Ma, WenwuX
> <wenwux.ma@intel.com>; He, Xingguang <xingguang.he@intel.com>;
> Thomas Monjalon <thomas@monjalon.net>; Richardson, Bruce
> <bruce.richardson@intel.com>; Ilya Maximets <imaximet@redhat.com>;
> David Marchand <david.marchand@redhat.com>
> Subject: Re: [PATCH v5] net/vhost: support asynchronous data path
> 
> Hi Jiayu,
> 
> On 10/25/22 04:14, Hu, Jiayu wrote:
> > Hi Maxime,
> >
> > Thanks for your comments. Please see replies inline.
> >
> >> -----Original Message-----
> >> From: Maxime Coquelin <maxime.coquelin@redhat.com>
> >> Sent: Monday, October 24, 2022 5:08 PM
> >> To: Wang, YuanX <yuanx.wang@intel.com>; Xia, Chenbo
> >> <chenbo.xia@intel.com>
> >> Cc: dev@dpdk.org; Hu, Jiayu <jiayu.hu@intel.com>; Jiang, Cheng1
> >> <cheng1.jiang@intel.com>; Ma, WenwuX <wenwux.ma@intel.com>; He,
> >> Xingguang <xingguang.he@intel.com>
> >> Subject: Re: [PATCH v5] net/vhost: support asynchronous data path
> >>
> >> Hi Yuan,
> >>
> >> Please fix your system for the next times, your patch is dated
> >> several hours in the future.
> >>
> >> On 10/24/22 17:14, Yuan Wang wrote:
> >>> Vhost asynchronous data-path offloads packet copy from the CPU to
> >>> the DMA engine. As a result, large packet copy can be accelerated by
> >>> the DMA engine, and vhost can free CPU cycles for higher level
> >>
> >> Vhost
> >>
> >>> functions.
> >>>
> >>> In this patch, we enable asynchronous data-path for vhostpmd.
> >>> Asynchronous data path is enabled per tx/rx queue, and users need to
> >>> specify the DMA device used by the tx/rx queue. Each tx/rx queue
> >>> only supports to use one DMA device, but one DMA device can be
> >>> shared
> >> among
> >>> multiple tx/rx queues of different vhost PMD ports.
> >>>
> >>> Two PMD parameters are added:
> >>> - dmas:	specify the used DMA device for a tx/rx queue.
> >>> 	(Default: no queues enable asynchronous data path)
> >>> - dma-ring-size: DMA ring size.
> >>> 	(Default: 4096).
> >>>
> >>> Here is an example:
> >>> --vdev
> >>
> 'eth_vhost0,iface=./s0,dmas=[txq0@0000:00.01.0;rxq0@0000:00.01.1],dma
> >> -
> >> ring-size=4096'
> >>>
> >>> Signed-off-by: Jiayu Hu <jiayu.hu@intel.com>
> >>> Signed-off-by: Yuan Wang <yuanx.wang@intel.com>
> >>> Signed-off-by: Wenwu Ma <wenwux.ma@intel.com>
> >>>
> >>> ---
> >>> v5:
> >>> - add error log of testpmd cmd
> >>>
> >>> v4:
> >>> - add txq allow_queuing check on poll completed
> >>> - unregister dma channel in destroy_device
> >>> - add dma ring size minimum limit
> >>> - fix serveral code style and logging issues
> >>>
> >>> v3:
> >>> - add the API to version.map
> >>>
> >>> v2:
> >>> - add missing file
> >>> - hide async_tx_poll_completed
> >>> - change default DMA ring size to 4096
> >>>
> >>> ---
> >>>    drivers/net/vhost/meson.build     |   1 +
> >>>    drivers/net/vhost/rte_eth_vhost.c | 512
> >> ++++++++++++++++++++++++++++--
> >>>    drivers/net/vhost/rte_eth_vhost.h |  15 +
> >>>    drivers/net/vhost/version.map     |   7 +
> >>>    drivers/net/vhost/vhost_testpmd.c |  67 ++++
> >>>    5 files changed, 569 insertions(+), 33 deletions(-)
> >>>    create mode 100644 drivers/net/vhost/vhost_testpmd.c
> >>>
> >>> diff --git a/drivers/net/vhost/meson.build
> >>> b/drivers/net/vhost/meson.build index f481a3a4b8..22a0ab3a58 100644
> >>> --- a/drivers/net/vhost/meson.build
> >>> +++ b/drivers/net/vhost/meson.build
> >>> @@ -9,4 +9,5 @@ endif
> >>>
> >>>    deps += 'vhost'
> >>>    sources = files('rte_eth_vhost.c')
> >>> +testpmd_sources = files('vhost_testpmd.c')
> >>>    headers = files('rte_eth_vhost.h') diff --git
> >>> a/drivers/net/vhost/rte_eth_vhost.c
> >>> b/drivers/net/vhost/rte_eth_vhost.c
> >>> index b152279fac..80cd9c8d92 100644
> >>> --- a/drivers/net/vhost/rte_eth_vhost.c
> >>> +++ b/drivers/net/vhost/rte_eth_vhost.c
> >>> @@ -7,6 +7,7 @@
> >>>    #include <pthread.h>
> >>>    #include <stdbool.h>
> >>>    #include <sys/epoll.h>
> >>> +#include <ctype.h>
> >>>
> >>>    #include <rte_mbuf.h>
> >>>    #include <ethdev_driver.h>
> >>> @@ -18,6 +19,8 @@
> >>>    #include <rte_kvargs.h>
> >>>    #include <rte_vhost.h>
> >>>    #include <rte_spinlock.h>
> >>> +#include <rte_vhost_async.h>
> >>> +#include <rte_dmadev.h>
> >>>
> >>>    #include "rte_eth_vhost.h"
> >>>
> >>> @@ -37,8 +40,15 @@ enum {VIRTIO_RXQ, VIRTIO_TXQ, VIRTIO_QNUM};
> >>>    #define ETH_VHOST_LINEAR_BUF		"linear-buffer"
> >>>    #define ETH_VHOST_EXT_BUF		"ext-buffer"
> >>>    #define ETH_VHOST_LEGACY_OL_FLAGS	"legacy-ol-flags"
> >>> +#define ETH_VHOST_DMA_ARG		"dmas"
> >>> +#define ETH_VHOST_DMA_RING_SIZE		"dma-ring-size"
> >>>    #define VHOST_MAX_PKT_BURST 32
> >>>
> >>> +#define INVALID_DMA_ID		-1
> >>> +#define DEFAULT_DMA_RING_SIZE	4096
> >>> +/* Minimum package size is 64, dma ring size should be greater than 32
> */
> >>> +#define MINIMUM_DMA_RING_SIZE	64
> >>
> >> Why? Is that related to Intel HW?
> >
> > No, it is for TCP/UDP tests. The max TCP/UDP length is 64KB, so one
> > packet needs 32 pktmbufs. If we set DMA ring size to 32, it's possible
> > that vhost cannot enqueue/dequeue one packet, as there may be some
> > control packets mixed and DMA ring full will cause enqueue/dequeue the
> > packet failed. So the recommend minimal DMA ring size is > 32.
> 
> I guess it depends on the mbuf size, doesn't it?
> I'm not against having a default value, but we need to understand the
> rationale by just reading the code and not having to ask the author.

Sure, we will remove the MINIMUM_DMA_RING_SIZE  macro and give more
explanation for DEFAULT_DMA_RING_SIZE.

> 
> >
> > We can remove the macro, but add one comment to suggest the DMA ring
> > size.
> >>
> >>> +
> >>>    static const char *valid_arguments[] = {
> >>>    	ETH_VHOST_IFACE_ARG,
> >>>    	ETH_VHOST_QUEUES_ARG,
> >>> @@ -49,6 +59,8 @@ static const char *valid_arguments[] = {
> >>>    	ETH_VHOST_LINEAR_BUF,
> >>>    	ETH_VHOST_EXT_BUF,
> >>>    	ETH_VHOST_LEGACY_OL_FLAGS,
> >>> +	ETH_VHOST_DMA_ARG,
> >>> +	ETH_VHOST_DMA_RING_SIZE,
> >>>    	NULL
> >>>    };
> >>>
> >>> @@ -80,8 +92,39 @@ struct vhost_queue {
> >>>    	struct vhost_stats stats;
> >>>    	int intr_enable;
> >>>    	rte_spinlock_t intr_lock;
> >>> +
> >>> +	/* Flag of enabling async data path */
> >>> +	bool async_register;
> >>> +	/* DMA device ID */
> >>> +	int16_t dma_id;
> >>> +	/**
> >>> +	 * For a Rx queue, "txq" points to its peer Tx queue.
> >>> +	 * For a Tx queue, "txq" is never used.
> >>> +	 */
> >>> +	struct vhost_queue *txq;
> >>> +	/* Array to keep DMA completed packets */
> >>> +	struct rte_mbuf *cmpl_pkts[VHOST_MAX_PKT_BURST];
> >>>    };
> >>>
> >>> +struct dma_input_info {
> >>> +	int16_t dmas[RTE_MAX_QUEUES_PER_PORT * 2];
> >>> +	uint16_t dma_ring_size;
> >>> +};
> >>> +
> >>> +static int16_t configured_dmas[RTE_DMADEV_DEFAULT_MAX];
> >>> +static int dma_count;
> >>> +
> >>> +/**
> >>> + * By default, its Rx path to call
> >>> +rte_vhost_poll_enqueue_completed() for
> >> enqueue operations.
> >>> + * However, Rx function is never been called in testpmd "txonly"
> >>> +mode, thus causing virtio
> >>> + * cannot receive DMA completed packets. To make txonly mode work
> >>> +correctly, we provide a
> >>> + * command in testpmd to call rte_vhost_poll_enqueue_completed() in
> >>> +Tx
> >> path.
> >>> + *
> >>> + * When set async_tx_poll_completed to true, Tx path calls
> >>> +rte_vhost_poll_enqueue_completed();
> >>> + * otherwise, Rx path calls it.
> >>> + */
> >>> +bool async_tx_poll_completed;
> >>> +
> >>>    struct pmd_internal {
> >>>    	rte_atomic32_t dev_attached;
> >>>    	char *iface_name;
> >>> @@ -94,6 +137,10 @@ struct pmd_internal {
> >>>    	bool vlan_strip;
> >>>    	bool rx_sw_csum;
> >>>    	bool tx_sw_csum;
> >>> +	struct {
> >>> +		int16_t dma_id;
> >>> +		bool async_register;
> >>> +	} queue_dmas[RTE_MAX_QUEUES_PER_PORT * 2];
> >>>    };
> >>>
> >>>    struct internal_list {
> >>> @@ -124,6 +171,17 @@ struct rte_vhost_vring_state {
> >>>
> >>>    static struct rte_vhost_vring_state
> >>> *vring_states[RTE_MAX_ETHPORTS];
> >>>
> >>> +static bool
> >>> +dma_is_configured(int16_t dma_id)
> >>> +{
> >>> +	int i;
> >>> +
> >>> +	for (i = 0; i < dma_count; i++)
> >>> +		if (configured_dmas[i] == dma_id)
> >>> +			return true;
> >>> +	return false;
> >>> +}
> >>> +
> >>>    static int
> >>>    vhost_dev_xstats_reset(struct rte_eth_dev *dev)
> >>>    {
> >>> @@ -396,15 +454,27 @@ vhost_dev_rx_sw_csum(struct rte_mbuf
> *mbuf)
> >>>    	mbuf->ol_flags |= RTE_MBUF_F_RX_L4_CKSUM_GOOD;
> >>>    }
> >>>
> >>> +static inline void
> >>> +vhost_tx_free_completed(int vid, uint16_t virtqueue_id, int16_t dma_id,
> >>> +		struct rte_mbuf **pkts, uint16_t count) {
> >>> +	uint16_t i, ret;
> >>> +
> >>> +	ret = rte_vhost_poll_enqueue_completed(vid, virtqueue_id, pkts,
> >> count, dma_id, 0);
> >>> +	for (i = 0; likely(i < ret); i++)
> >>> +		rte_pktmbuf_free(pkts[i]);
> >>> +}
> >>> +
> >>>    static uint16_t
> >>>    eth_vhost_rx(void *q, struct rte_mbuf **bufs, uint16_t nb_bufs)
> >>>    {
> >>>    	struct vhost_queue *r = q;
> >>>    	uint16_t i, nb_rx = 0;
> >>>    	uint16_t nb_receive = nb_bufs;
> >>> +	uint16_t nb_pkts, num;
> >>>
> >>>    	if (unlikely(rte_atomic32_read(&r->allow_queuing) == 0))
> >>> -		return 0;
> >>> +		goto tx_poll;
> >>>
> >>>    	rte_atomic32_set(&r->while_queuing, 1);
> >>>
> >>> @@ -412,19 +482,32 @@ eth_vhost_rx(void *q, struct rte_mbuf **bufs,
> >> uint16_t nb_bufs)
> >>>    		goto out;
> >>>
> >>>    	/* Dequeue packets from guest TX queue */
> >>> -	while (nb_receive) {
> >>> -		uint16_t nb_pkts;
> >>> -		uint16_t num = (uint16_t)RTE_MIN(nb_receive,
> >>> -						 VHOST_MAX_PKT_BURST);
> >>> -
> >>> -		nb_pkts = rte_vhost_dequeue_burst(r->vid, r->virtqueue_id,
> >>> -						  r->mb_pool, &bufs[nb_rx],
> >>> -						  num);
> >>> -
> >>> -		nb_rx += nb_pkts;
> >>> -		nb_receive -= nb_pkts;
> >>> -		if (nb_pkts < num)
> >>> -			break;
> >>> +	if (!r->async_register) {
> >>> +		while (nb_receive) {
> >>> +			num = (uint16_t)RTE_MIN(nb_receive,
> >> VHOST_MAX_PKT_BURST);
> >>> +			nb_pkts = rte_vhost_dequeue_burst(r->vid, r-
> >>> virtqueue_id,
> >>> +						r->mb_pool, &bufs[nb_rx],
> >>> +						num);
> >>> +
> >>> +			nb_rx += nb_pkts;
> >>> +			nb_receive -= nb_pkts;
> >>> +			if (nb_pkts < num)
> >>> +				break;
> >>> +		}
> >>> +	} else {
> >>> +		int nr_inflight;
> >>> +
> >>> +		while (nb_receive) {
> >>> +			num = (uint16_t)RTE_MIN(nb_receive,
> >> VHOST_MAX_PKT_BURST);
> >>> +			nb_pkts = rte_vhost_async_try_dequeue_burst(r-
> >>> vid, r->virtqueue_id,
> >>> +						r->mb_pool, &bufs[nb_rx],
> >> num, &nr_inflight,
> >>> +						r->dma_id, 0);
> >>> +
> >>> +			nb_rx += nb_pkts;
> >>> +			nb_receive -= nb_pkts;
> >>> +			if (nb_pkts < num)
> >>> +				break;
> >>> +		}
> >>>    	}
> >>>
> >>>    	r->stats.pkts += nb_rx;
> >>> @@ -445,6 +528,17 @@ eth_vhost_rx(void *q, struct rte_mbuf **bufs,
> >> uint16_t nb_bufs)
> >>>    out:
> >>>    	rte_atomic32_set(&r->while_queuing, 0);
> >>>
> >>> +tx_poll:
> >>> +	/**
> >>> +	 * Poll and free completed packets for the virtqueue of Tx queue.
> >>> +	 * Note that we access Tx queue's virtqueue, which is protected
> >>> +	 * by vring lock.
> >>> +	 */
> >>> +	if (r->txq->async_register && !async_tx_poll_completed &&
> >>> +			rte_atomic32_read(&r->txq->allow_queuing) == 1)
> >>> +		vhost_tx_free_completed(r->vid, r->txq->virtqueue_id, r-
> >>> txq->dma_id,
> >>> +				r->cmpl_pkts, VHOST_MAX_PKT_BURST);
> >>> +
> >>>    	return nb_rx;
> >>>    }
> >>>
> >>> @@ -456,6 +550,7 @@ eth_vhost_tx(void *q, struct rte_mbuf **bufs,
> >> uint16_t nb_bufs)
> >>>    	uint16_t nb_send = 0;
> >>>    	uint64_t nb_bytes = 0;
> >>>    	uint64_t nb_missed = 0;
> >>> +	uint16_t nb_pkts, num;
> >>>
> >>>    	if (unlikely(rte_atomic32_read(&r->allow_queuing) == 0))
> >>>    		return 0;
> >>> @@ -486,31 +581,49 @@ eth_vhost_tx(void *q, struct rte_mbuf **bufs,
> >> uint16_t nb_bufs)
> >>>    	}
> >>>
> >>>    	/* Enqueue packets to guest RX queue */
> >>> -	while (nb_send) {
> >>> -		uint16_t nb_pkts;
> >>> -		uint16_t num = (uint16_t)RTE_MIN(nb_send,
> >>> -						 VHOST_MAX_PKT_BURST);
> >>> +	if (!r->async_register) {
> >>> +		while (nb_send) {
> >>> +			num = (uint16_t)RTE_MIN(nb_send,
> >> VHOST_MAX_PKT_BURST);
> >>> +			nb_pkts = rte_vhost_enqueue_burst(r->vid, r-
> >>> virtqueue_id,
> >>> +						&bufs[nb_tx], num);
> >>> +
> >>> +			nb_tx += nb_pkts;
> >>> +			nb_send -= nb_pkts;
> >>> +			if (nb_pkts < num)
> >>> +				break;
> >>> +		}
> >>>
> >>> -		nb_pkts = rte_vhost_enqueue_burst(r->vid, r->virtqueue_id,
> >>> -						  &bufs[nb_tx], num);
> >>> +		for (i = 0; likely(i < nb_tx); i++) {
> >>> +			nb_bytes += bufs[i]->pkt_len;
> >>> +			rte_pktmbuf_free(bufs[i]);
> >>> +		}
> >>>
> >>> -		nb_tx += nb_pkts;
> >>> -		nb_send -= nb_pkts;
> >>> -		if (nb_pkts < num)
> >>> -			break;
> >>> -	}
> >>> +	} else {
> >>> +		while (nb_send) {
> >>> +			num = (uint16_t)RTE_MIN(nb_send,
> >> VHOST_MAX_PKT_BURST);
> >>> +			nb_pkts = rte_vhost_submit_enqueue_burst(r->vid,
> >> r->virtqueue_id,
> >>> +							&bufs[nb_tx], num, r-
> >>> dma_id, 0);
> >>> +
> >>> +			nb_tx += nb_pkts;
> >>> +			nb_send -= nb_pkts;
> >>> +			if (nb_pkts < num)
> >>> +				break;
> >>> +		}
> >>>
> >>> -	for (i = 0; likely(i < nb_tx); i++)
> >>> -		nb_bytes += bufs[i]->pkt_len;
> >>> +		for (i = 0; likely(i < nb_tx); i++)
> >>> +			nb_bytes += bufs[i]->pkt_len;
> >>>
> >>> -	nb_missed = nb_bufs - nb_tx;
> >>> +		if (unlikely(async_tx_poll_completed)) {
> >>> +			vhost_tx_free_completed(r->vid, r->virtqueue_id, r-
> >>> dma_id, r->cmpl_pkts,
> >>> +					VHOST_MAX_PKT_BURST);
> >>> +		}
> >>> +	}
> >>>
> >>> +	nb_missed = nb_bufs - nb_tx;
> >>>    	r->stats.pkts += nb_tx;
> >>>    	r->stats.bytes += nb_bytes;
> >>>    	r->stats.missed_pkts += nb_missed;
> >>>
> >>> -	for (i = 0; likely(i < nb_tx); i++)
> >>> -		rte_pktmbuf_free(bufs[i]);
> >>>    out:
> >>>    	rte_atomic32_set(&r->while_queuing, 0);
> >>>
> >>> @@ -798,6 +911,8 @@ queue_setup(struct rte_eth_dev *eth_dev, struct
> >> pmd_internal *internal)
> >>>    		vq->vid = internal->vid;
> >>>    		vq->internal = internal;
> >>>    		vq->port = eth_dev->data->port_id;
> >>> +		if (i < eth_dev->data->nb_tx_queues)
> >>> +			vq->txq = eth_dev->data->tx_queues[i];
> >>>    	}
> >>>    	for (i = 0; i < eth_dev->data->nb_tx_queues; i++) {
> >>>    		vq = eth_dev->data->tx_queues[i]; @@ -878,6 +993,30 @@
> >>> new_device(int vid)
> >>>    	return 0;
> >>>    }
> >>>
> >>> +static inline void
> >>> +async_clear_virtqueue(int vid, uint16_t virtqueue_id, int16_t
> >>> +dma_id) {
> >>> +	struct rte_mbuf *pkts[VHOST_MAX_PKT_BURST];
> >>> +	uint16_t i, ret, nr_done = 0;
> >>> +
> >>> +	if (vid == -1)
> >>> +		return;
> >>> +
> >>> +	while (rte_vhost_async_get_inflight(vid, virtqueue_id) > 0) {
> >>> +		ret = rte_vhost_clear_queue(vid, virtqueue_id, pkts,
> >> VHOST_MAX_PKT_BURST, dma_id,
> >>> +				0);
> >>> +		for (i = 0; i < ret ; i++)
> >>> +			rte_pktmbuf_free(pkts[i]);
> >>> +
> >>> +		nr_done += ret;
> >>> +	}
> >>> +	VHOST_LOG(INFO, "Completed %u pkts for vid-%u vring-%u\n",
> >> nr_done,
> >>> +vid, virtqueue_id);
> >>> +
> >>> +	if (rte_vhost_async_channel_unregister(vid, virtqueue_id))
> >>> +		VHOST_LOG(ERR, "Failed to unregister async for vid-%u
> >> vring-%u\n", vid,
> >>> +				virtqueue_id);
> >>> +}
> >>> +
> >>>    static void
> >>>    destroy_device(int vid)
> >>>    {
> >>> @@ -908,13 +1047,27 @@ destroy_device(int vid)
> >>>    			vq = eth_dev->data->rx_queues[i];
> >>>    			if (!vq)
> >>>    				continue;
> >>> +			if (vq->async_register) {
> >>> +				async_clear_virtqueue(vq->vid, vq-
> >>> virtqueue_id,
> >>> +							vq->dma_id);
> >>> +				vq->async_register = false;
> >>> +				internal->queue_dmas[vq-
> >>> virtqueue_id].async_register = false;
> >>> +			}
> >>>    			vq->vid = -1;
> >>> +
> >>>    		}
> >>>    		for (i = 0; i < eth_dev->data->nb_tx_queues; i++) {
> >>>    			vq = eth_dev->data->tx_queues[i];
> >>>    			if (!vq)
> >>>    				continue;
> >>> +			if (vq->async_register) {
> >>> +				async_clear_virtqueue(vq->vid, vq-
> >>> virtqueue_id,
> >>> +							vq->dma_id);
> >>> +				vq->async_register = false;
> >>> +				internal->queue_dmas[vq-
> >>> virtqueue_id].async_register = false;
> >>> +			}
> >>>    			vq->vid = -1;
> >>> +
> >>>    		}
> >>>    	}
> >>>
> >>> @@ -983,6 +1136,9 @@ vring_state_changed(int vid, uint16_t vring,
> >>> int
> >> enable)
> >>>    	struct rte_vhost_vring_state *state;
> >>>    	struct rte_eth_dev *eth_dev;
> >>>    	struct internal_list *list;
> >>> +	struct vhost_queue *queue;
> >>> +	struct pmd_internal *internal;
> >>> +	int qid;
> >>>    	char ifname[PATH_MAX];
> >>>
> >>>    	rte_vhost_get_ifname(vid, ifname, sizeof(ifname)); @@ -1011,6
> >>> +1167,65 @@ vring_state_changed(int vid, uint16_t vring, int enable)
> >>>
> >>>    	update_queuing_status(eth_dev, false);
> >>>
> >>> +	qid = vring / VIRTIO_QNUM;
> >>> +	if (vring % VIRTIO_QNUM == VIRTIO_RXQ)
> >>> +		queue = eth_dev->data->tx_queues[qid];
> >>> +	else
> >>> +		queue = eth_dev->data->rx_queues[qid];
> >>> +
> >>> +	if (!queue)
> >>> +		goto skip;
> >>> +
> >>> +	internal = eth_dev->data->dev_private;
> >>> +
> >>> +	/* Register async data path for the queue assigned valid DMA
> >>> +device
> >> */
> >>> +	if (internal->queue_dmas[queue->virtqueue_id].dma_id ==
> >> INVALID_DMA_ID)
> >>> +		goto skip;
> >>> +
> >>> +	if (enable && !queue->async_register) {
> >>> +		if (rte_vhost_async_channel_register_thread_unsafe(vid,
> >> vring)) {
> >>> +			VHOST_LOG(ERR, "Failed to register async for vid-%u
> >> vring-%u!\n", vid,
> >>> +					vring);
> >>> +			return -1;
> >>> +		}
> >>> +
> >>> +		queue->async_register = true;
> >>> +		internal->queue_dmas[vring].async_register = true;
> >>> +
> >>> +		VHOST_LOG(INFO, "Succeed to register async for vid-%u
> >> vring-%u\n", vid, vring);
> >>> +	}
> >>> +
> >>> +	if (!enable && queue->async_register) {
> >>> +		struct rte_mbuf *pkts[VHOST_MAX_PKT_BURST];
> >>> +		uint16_t ret, i, nr_done = 0;
> >>> +		uint16_t dma_id = queue->dma_id;
> >>> +
> >>> +		while (rte_vhost_async_get_inflight_thread_unsafe(vid,
> >> vring) > 0) {
> >>> +			ret = rte_vhost_clear_queue_thread_unsafe(vid,
> >> vring, pkts,
> >>> +					VHOST_MAX_PKT_BURST, dma_id, 0);
> >>> +
> >>> +			for (i = 0; i < ret ; i++)
> >>> +				rte_pktmbuf_free(pkts[i]);
> >>> +
> >>> +			nr_done += ret;
> >>> +		}
> >>> +
> >>> +		VHOST_LOG(INFO, "Completed %u in-flight pkts for vid-%u
> >> vring-%u\n", nr_done, vid,
> >>> +				vring);
> >>> +
> >>> +		if (rte_vhost_async_channel_unregister_thread_unsafe(vid,
> >> vring)) {
> >>> +			VHOST_LOG(ERR, "Failed to unregister async for vid-
> >> %u vring-%u\n", vid,
> >>> +					vring);
> >>> +			return -1;
> >>> +		}
> >>> +
> >>> +		queue->async_register = false;
> >>> +		internal->queue_dmas[vring].async_register = false;
> >>> +
> >>> +		VHOST_LOG(INFO, "Succeed to unregister async for vid-%u
> >> vring-%u\n", vid, vring);
> >>> +	}
> >>> +
> >>> +skip:
> >>>    	VHOST_LOG(INFO, "vring%u is %s\n",
> >>>    			vring, enable ? "enabled" : "disabled");
> >>>
> >>> @@ -1159,6 +1374,12 @@
> rte_eth_vhost_get_vid_from_port_id(uint16_t
> >> port_id)
> >>>    	return vid;
> >>>    }
> >>>
> >>> +void
> >>> +rte_eth_vhost_async_tx_poll_completed(bool enable) {
> >>> +	async_tx_poll_completed = enable;
> >>> +}
> >>> +
> >>>    static int
> >>>    eth_dev_configure(struct rte_eth_dev *dev)
> >>>    {
> >>> @@ -1220,6 +1441,7 @@ eth_dev_close(struct rte_eth_dev *dev)
> >>>    {
> >>>    	struct pmd_internal *internal;
> >>>    	struct internal_list *list;
> >>> +	struct vhost_queue *queue;
> >>>    	unsigned int i, ret;
> >>>
> >>>    	if (rte_eal_process_type() != RTE_PROC_PRIMARY) @@ -1233,6
> >> +1455,25
> >>> @@ eth_dev_close(struct rte_eth_dev *dev)
> >>>
> >>>    	list = find_internal_resource(internal->iface_name);
> >>>    	if (list) {
> >>> +		/* Make sure all in-flight packets are completed before
> >> destroy vhost */
> >>> +		if (dev->data->rx_queues) {
> >>> +			for (i = 0; i < dev->data->nb_rx_queues; i++) {
> >>> +				queue = dev->data->rx_queues[i];
> >>> +				if (queue->async_register)
> >>> +					async_clear_virtqueue(queue->vid,
> >> queue->virtqueue_id,
> >>> +							queue->dma_id);
> >>> +			}
> >>> +		}
> >>> +
> >>> +		if (dev->data->tx_queues) {
> >>> +			for (i = 0; i < dev->data->nb_tx_queues; i++) {
> >>> +				queue = dev->data->tx_queues[i];
> >>> +				if (queue->async_register)
> >>> +					async_clear_virtqueue(queue->vid,
> >> queue->virtqueue_id,
> >>> +							queue->dma_id);
> >>> +			}
> >>> +		}
> >>> +
> >>>    		rte_vhost_driver_unregister(internal->iface_name);
> >>>    		pthread_mutex_lock(&internal_list_lock);
> >>>    		TAILQ_REMOVE(&internal_list, list, next); @@ -1267,6
> >> +1508,7 @@
> >>> eth_rx_queue_setup(struct rte_eth_dev *dev, uint16_t rx_queue_id,
> >>>    		   struct rte_mempool *mb_pool)
> >>>    {
> >>>    	struct vhost_queue *vq;
> >>> +	struct pmd_internal *internal = dev->data->dev_private;
> >>>
> >>>    	vq = rte_zmalloc_socket(NULL, sizeof(struct vhost_queue),
> >>>    			RTE_CACHE_LINE_SIZE, socket_id); @@ -1277,6
> +1519,8 @@
> >>> eth_rx_queue_setup(struct rte_eth_dev *dev, uint16_t rx_queue_id,
> >>>
> >>>    	vq->mb_pool = mb_pool;
> >>>    	vq->virtqueue_id = rx_queue_id * VIRTIO_QNUM + VIRTIO_TXQ;
> >>> +	vq->async_register = internal->queue_dmas[vq-
> >>> virtqueue_id].async_register;
> >>> +	vq->dma_id = internal->queue_dmas[vq->virtqueue_id].dma_id;
> >>>    	rte_spinlock_init(&vq->intr_lock);
> >>>    	dev->data->rx_queues[rx_queue_id] = vq;
> >>>
> >>> @@ -1290,6 +1534,7 @@ eth_tx_queue_setup(struct rte_eth_dev *dev,
> >> uint16_t tx_queue_id,
> >>>    		   const struct rte_eth_txconf *tx_conf __rte_unused)
> >>>    {
> >>>    	struct vhost_queue *vq;
> >>> +	struct pmd_internal *internal = dev->data->dev_private;
> >>>
> >>>    	vq = rte_zmalloc_socket(NULL, sizeof(struct vhost_queue),
> >>>    			RTE_CACHE_LINE_SIZE, socket_id); @@ -1299,6
> +1544,8 @@
> >>> eth_tx_queue_setup(struct rte_eth_dev *dev,
> >> uint16_t tx_queue_id,
> >>>    	}
> >>>
> >>>    	vq->virtqueue_id = tx_queue_id * VIRTIO_QNUM + VIRTIO_RXQ;
> >>> +	vq->async_register = internal->queue_dmas[vq-
> >>> virtqueue_id].async_register;
> >>> +	vq->dma_id = internal->queue_dmas[vq->virtqueue_id].dma_id;
> >>>    	rte_spinlock_init(&vq->intr_lock);
> >>>    	dev->data->tx_queues[tx_queue_id] = vq;
> >>>
> >>> @@ -1509,13 +1756,14 @@ static const struct eth_dev_ops ops = {
> >>>    static int
> >>>    eth_dev_vhost_create(struct rte_vdev_device *dev, char *iface_name,
> >>>    	int16_t queues, const unsigned int numa_node, uint64_t flags,
> >>> -	uint64_t disable_flags)
> >>> +	uint64_t disable_flags, struct dma_input_info *dma_input)
> >>>    {
> >>>    	const char *name = rte_vdev_device_name(dev);
> >>>    	struct rte_eth_dev_data *data;
> >>>    	struct pmd_internal *internal = NULL;
> >>>    	struct rte_eth_dev *eth_dev = NULL;
> >>>    	struct rte_ether_addr *eth_addr = NULL;
> >>> +	int i;
> >>>
> >>>    	VHOST_LOG(INFO, "Creating VHOST-USER backend on numa
> >> socket %u\n",
> >>>    		numa_node);
> >>> @@ -1564,6 +1812,12 @@ eth_dev_vhost_create(struct rte_vdev_device
> >> *dev, char *iface_name,
> >>>    	eth_dev->rx_pkt_burst = eth_vhost_rx;
> >>>    	eth_dev->tx_pkt_burst = eth_vhost_tx;
> >>>
> >>> +	for (i = 0; i < RTE_MAX_QUEUES_PER_PORT * 2; i++) {
> >>> +		/* Invalid DMA ID indicates the queue does not want to
> >> enable async data path */
> >>> +		internal->queue_dmas[i].dma_id = dma_input->dmas[i];
> >>> +		internal->queue_dmas[i].async_register = false;
> >>> +	}
> >>> +
> >>>    	rte_eth_dev_probing_finish(eth_dev);
> >>>    	return 0;
> >>>
> >>> @@ -1603,6 +1857,155 @@ open_int(const char *key __rte_unused,
> const
> >> char *value, void *extra_args)
> >>>    	return 0;
> >>>    }
> >>>
> >>> +static int
> >>> +init_dma(int16_t dma_id, uint16_t ring_size) {
> >>> +	struct rte_dma_info info;
> >>> +	struct rte_dma_conf dev_config = { .nb_vchans = 1 };
> >>> +	struct rte_dma_vchan_conf qconf = {
> >>> +		.direction = RTE_DMA_DIR_MEM_TO_MEM,
> >>> +	};
> >>> +	int ret = 0;
> >>> +
> >>> +	if (dma_is_configured(dma_id))
> >>> +		goto out;
> >>> +
> >>> +	if (rte_dma_info_get(dma_id, &info) != 0) {
> >>> +		VHOST_LOG(ERR, "dma %u get info failed\n", dma_id);
> >>> +		ret = -1;
> >>> +		goto out;
> >>> +	}
> >>> +
> >>> +	if (info.max_vchans < 1) {
> >>> +		VHOST_LOG(ERR, "No channels available on dma %d\n",
> >> dma_id);
> >>> +		ret = -1;
> >>> +		goto out;
> >>> +	}
> >>> +
> >>> +	if (rte_dma_configure(dma_id, &dev_config) != 0) {
> >>> +		VHOST_LOG(ERR, "dma %u configure failed\n", dma_id);
> >>> +		ret = -1;
> >>> +		goto out;
> >>> +	}
> >>> +
> >>> +	rte_dma_info_get(dma_id, &info);
> >>> +	if (info.nb_vchans != 1) {
> >>> +		VHOST_LOG(ERR, "dma %u has no queues\n", dma_id);
> >>> +		ret = -1;
> >>> +		goto out;
> >>> +	}
> >>> +
> >>> +	ring_size = RTE_MAX(ring_size, MINIMUM_DMA_RING_SIZE);
> >>> +	ring_size = RTE_MAX(ring_size, info.min_desc);
> >>> +	qconf.nb_desc = RTE_MIN(ring_size, info.max_desc);
> >>> +	if (rte_dma_vchan_setup(dma_id, 0, &qconf) != 0) {
> >>> +		VHOST_LOG(ERR, "dma %u queue setup failed\n", dma_id);
> >>> +		ret = -1;
> >>> +		goto out;
> >>> +	}
> >>> +
> >>> +	if (rte_dma_start(dma_id) != 0) {
> >>> +		VHOST_LOG(ERR, "dma %u start failed\n", dma_id);
> >>> +		ret = -1;
> >>> +		goto out;
> >>> +	}
> >>> +
> >>> +	configured_dmas[dma_count++] = dma_id;
> >>> +
> >>> +out:
> >>> +	return ret;
> >>> +}
> >>> +
> >>> +static int
> >>> +open_dma(const char *key __rte_unused, const char *value, void
> >>> +*extra_args) {
> >>> +	struct dma_input_info *dma_input = extra_args;
> >>> +	char *input = strndup(value, strlen(value) + 1);
> >>> +	char *addrs = input;
> >>> +	char *ptrs[2];
> >>> +	char *start, *end, *substr;
> >>> +	uint16_t qid, virtqueue_id;
> >>> +	int16_t dma_id;
> >>> +	int i, ret = 0;
> >>> +
> >>> +	while (isblank(*addrs))
> >>> +		addrs++;
> >>> +	if (*addrs == '\0') {
> >>> +		VHOST_LOG(ERR, "No input DMA addresses\n");
> >>> +		ret = -1;
> >>> +		goto out;
> >>> +	}
> >>> +
> >>> +	/* process DMA devices within bracket. */
> >>> +	addrs++;
> >>> +	substr = strtok(addrs, ";]");
> >>> +	if (!substr) {
> >>> +		VHOST_LOG(ERR, "No input DMA addresse\n");
> >>> +		ret = -1;
> >>> +		goto out;
> >>> +	}
> >>> +
> >>> +	do {
> >>> +		rte_strsplit(substr, strlen(substr), ptrs, 2, '@');
> >>> +
> >>> +		char *txq, *rxq;
> >>> +		bool is_txq;
> >>> +
> >>> +		txq = strstr(ptrs[0], "txq");
> >>> +		rxq = strstr(ptrs[0], "rxq");
> >>> +		if (txq == NULL && rxq == NULL) {
> >>> +			VHOST_LOG(ERR, "Illegal queue\n");
> >>> +			ret = -1;
> >>> +			goto out;
> >>> +		} else if (txq) {
> >>> +			is_txq = true;
> >>> +			start = txq;
> >>> +		} else {
> >>> +			is_txq = false;
> >>> +			start = rxq;
> >>> +		}
> >>> +
> >>> +		start += 3;
> >>> +		qid = strtol(start, &end, 0);
> >>> +		if (end == start) {
> >>> +			VHOST_LOG(ERR, "No input queue ID\n");
> >>> +			ret = -1;
> >>> +			goto out;
> >>> +		}
> >>> +
> >>> +		virtqueue_id = is_txq ? qid * 2 + VIRTIO_RXQ : qid * 2 +
> >>> +VIRTIO_TXQ;
> >>> +
> >>> +		dma_id = rte_dma_get_dev_id_by_name(ptrs[1]);
> >>> +		if (dma_id < 0) {
> >>> +			VHOST_LOG(ERR, "Fail to find DMA device %s.\n",
> >> ptrs[1]);
> >>> +			ret = -1;
> >>> +			goto out;
> >>> +		}
> >>> +
> >>> +		ret = init_dma(dma_id, dma_input->dma_ring_size);
> >>> +		if (ret != 0) {
> >>> +			VHOST_LOG(ERR, "Fail to initialize DMA %u\n",
> >> dma_id);
> >>> +			ret = -1;
> >>> +			break;
> >>> +		}
> >>> +
> >>> +		dma_input->dmas[virtqueue_id] = dma_id;
> >>> +
> >>> +		substr = strtok(NULL, ";]");
> >>> +	} while (substr);
> >>> +
> >>> +	for (i = 0; i < dma_count; i++) {
> >>> +		if (rte_vhost_async_dma_configure(configured_dmas[i], 0) <
> >> 0) {
> >>> +			VHOST_LOG(ERR, "Fail to configure DMA %u to
> >> vhost\n", configured_dmas[i]);
> >>> +			ret = -1;
> >>> +		}
> >>> +	}
> >>> +
> >>> +out:
> >>> +	free(input);
> >>> +	return ret;
> >>> +}
> >>> +
> >>>    static int
> >>>    rte_pmd_vhost_probe(struct rte_vdev_device *dev)
> >>>    {
> >>> @@ -1621,6 +2024,10 @@ rte_pmd_vhost_probe(struct
> rte_vdev_device
> >> *dev)
> >>>    	int legacy_ol_flags = 0;
> >>>    	struct rte_eth_dev *eth_dev;
> >>>    	const char *name = rte_vdev_device_name(dev);
> >>> +	struct dma_input_info dma_input;
> >>> +
> >>> +	memset(dma_input.dmas, INVALID_DMA_ID,
> >> sizeof(dma_input.dmas));
> >>> +	dma_input.dma_ring_size = DEFAULT_DMA_RING_SIZE;
> >>>
> >>>    	VHOST_LOG(INFO, "Initializing pmd_vhost for %s\n", name);
> >>>
> >>> @@ -1736,6 +2143,43 @@ rte_pmd_vhost_probe(struct
> rte_vdev_device
> >> *dev)
> >>>    			goto out_free;
> >>>    	}
> >>>
> >>> +	if (rte_kvargs_count(kvlist, ETH_VHOST_DMA_RING_SIZE) == 1) {
> >>> +		if (rte_kvargs_count(kvlist, ETH_VHOST_DMA_ARG) == 1) {
> >>> +			ret = rte_kvargs_process(kvlist,
> >> ETH_VHOST_DMA_RING_SIZE,
> >>> +					&open_int,
> >> &dma_input.dma_ring_size);
> >>> +			if (ret < 0)
> >>> +				goto out_free;
> >>> +
> >>> +			if (!rte_is_power_of_2(dma_input.dma_ring_size)) {
> >>> +				dma_input.dma_ring_size =
> >> rte_align32pow2(dma_input.dma_ring_size);
> >>> +				VHOST_LOG(INFO, "Convert dma_ring_size to
> >> the power of two %u\n",
> >>> +						dma_input.dma_ring_size);
> >>> +			}
> >>> +		} else {
> >>> +			VHOST_LOG(WARNING, "%s is not specified, skip to
> >> parse %s\n",
> >>> +					ETH_VHOST_DMA_ARG,
> >> ETH_VHOST_DMA_RING_SIZE);
> >>> +		}
> >>> +	}
> >>> +
> >>> +	if (rte_kvargs_count(kvlist, ETH_VHOST_DMA_ARG) == 1) {
> >>> +		if (rte_kvargs_count(kvlist, ETH_VHOST_DMA_RING_SIZE) ==
> >> 0)
> >>> +			VHOST_LOG(INFO, "Use default dma ring size %d\n",
> >>> +DEFAULT_DMA_RING_SIZE);
> >>> +
> >>> +		ret = rte_kvargs_process(kvlist, ETH_VHOST_DMA_ARG,
> >>> +					 &open_dma, &dma_input);
> >>> +		if (ret < 0) {
> >>> +			VHOST_LOG(ERR, "Failed to parse %s\n",
> >> ETH_VHOST_DMA_ARG);
> >>> +			goto out_free;
> >>> +		}
> >>> +
> >>> +		flags |= RTE_VHOST_USER_ASYNC_COPY;
> >>> +		/**
> >>> +		 * Don't support live migration when enable
> >>> +		 * DMA acceleration.
> >>> +		 */
> >>> +		disable_flags |= (1ULL << VHOST_F_LOG_ALL);
> >>> +	}
> >>> +
> >>>    	if (legacy_ol_flags == 0)
> >>>    		flags |= RTE_VHOST_USER_NET_COMPLIANT_OL_FLAGS;
> >>>
> >>> @@ -1743,7 +2187,7 @@ rte_pmd_vhost_probe(struct rte_vdev_device
> >> *dev)
> >>>    		dev->device.numa_node = rte_socket_id();
> >>>
> >>>    	ret = eth_dev_vhost_create(dev, iface_name, queues,
> >>> -				   dev->device.numa_node, flags,
> >> disable_flags);
> >>> +			dev->device.numa_node, flags, disable_flags,
> >> &dma_input);
> >>>    	if (ret == -1)
> >>>    		VHOST_LOG(ERR, "Failed to create %s\n", name);
> >>>
> >>> @@ -1787,4 +2231,6 @@
> RTE_PMD_REGISTER_PARAM_STRING(net_vhost,
> >>>    	"postcopy-support=<0|1> "
> >>>    	"tso=<0|1> "
> >>>    	"linear-buffer=<0|1> "
> >>> -	"ext-buffer=<0|1>");
> >>> +	"ext-buffer=<0|1> "
> >>> +	"dma-ring-size=<int> "
> >>> +	"dmas=[txq0@dma_addr;rxq0@dma_addr]");
> >>> diff --git a/drivers/net/vhost/rte_eth_vhost.h
> >>> b/drivers/net/vhost/rte_eth_vhost.h
> >>> index 0e68b9f668..146c98803d 100644
> >>> --- a/drivers/net/vhost/rte_eth_vhost.h
> >>> +++ b/drivers/net/vhost/rte_eth_vhost.h
> >>> @@ -52,6 +52,21 @@ int rte_eth_vhost_get_queue_event(uint16_t
> port_id,
> >>>     */
> >>>    int rte_eth_vhost_get_vid_from_port_id(uint16_t port_id);
> >>>
> >>> +/**
> >>> + * @warning
> >>> + * @b EXPERIMENTAL: this API may change, or be removed, without
> >>> +prior notice
> >>> + *
> >>> + * By default, rte_vhost_poll_enqueue_completed() is called in Rx path.
> >>> + * This function enables Tx path, rather than Rx path, to poll
> >>> +completed
> >>> + * packets for vhost async enqueue operations. Note that virtio may
> >>> +never
> >>> + * receive DMA completed packets if there are no more Tx operations.
> >>> + *
> >>> + * @param enable
> >>> + *  True indicates Tx path to call rte_vhost_poll_enqueue_completed().
> >>> + */
> >>> +__rte_experimental
> >>> +void rte_eth_vhost_async_tx_poll_completed(bool enable);
> >>> +
> >>>    #ifdef __cplusplus
> >>>    }
> >>>    #endif
> >>> diff --git a/drivers/net/vhost/version.map
> >>> b/drivers/net/vhost/version.map index e42c89f1eb..0a40441227 100644
> >>> --- a/drivers/net/vhost/version.map
> >>> +++ b/drivers/net/vhost/version.map
> >>> @@ -6,3 +6,10 @@ DPDK_23 {
> >>>
> >>>    	local: *;
> >>>    };
> >>> +
> >>> +EXPERIMENTAL {
> >>> +	global:
> >>> +
> >>> +	# added in 22.11
> >>> +	rte_eth_vhost_async_tx_poll_completed;
> >>
> >> I'm not in favor of adding driver-specific API.
> >> IMHO, you should just decide whether doing completion on Tx or Rx
> >> path and stick with it.
> >>
> >> Doing completion on the Tx path not being reliable (i.e. if not other
> >> packets are sent, last enqueued packets are not completed), I guess
> >> only doing completion in Rx path is the right thing to do.
> >
> > It's good to know your thoughts. But if we remove the driver-specific
> > API and put poll_enqueue_completed in Rx path, Testpmd txonly mode
> > cannot work with DMA accelerated enqueue, as no one will call
> poll_enqueue_completed.
> > Any thoughts?
> 
> I think it proves the async feature is not usable as it is implemented today.
> 
> Expecting the user to know he has to select or change at runtime the tx
> completion mode for the feature to just work (not only a performance
> tuning) is not acceptable IMHO.
> 
> To summarize:
>   - By default, Tx completion are done by the Rx path so txonly mode is not
> working (and nothing will notify the user).
>   - If user switch to Tx completion are done by the Tx path, last packet will
> never be completed.

Another way is to call rte_vhost_poll_enqueue_completed in both Rx and Tx
path. In this way, we will not have the issues above, and the performance drop
is not too much (it is ~10%, compared with calling in Tx path).

Does it make sense?

> 
> It may work for benchmark, but it is not usable in real-life.

IMHO, Vhost PMD is for benchmark purpose. No real applications use
Vhost PMD. The motivation of enabling asynchronous data path in Vhost
PMD is to demonstrate the performance of DMA accelerated data path
too.

> I think that for Vhost PMD, the Virtio completions should either be
> performed by DMA engine or by a dedicated thread.

We cannot depend on DMA engine to do completion, as there is no
ordering guarantee on the HW. For example, given the DMA engine
issues two updates on the used ring's index, it is possible that the second
write completes before the first one.

For a dedicated thread, the scalability may become the issue. Performance
could drop due to multiple cores read/write shared data.

For real workload integration, I believe there are already lots of discussions
on OVS. But for this patch, it is more as a benchmark to demonstrate the
benefits from DMA acceleration, IMHO.

Thanks,
Jiayu
> 
> Regards,
> Maxime
> 
> >
> > Thanks,
> > Jiayu
Maxime Coquelin Oct. 25, 2022, 3:33 p.m. UTC | #7
On 10/25/22 11:15, Hu, Jiayu wrote:
> Hi Maxime,
> 
>> -----Original Message-----
>> From: Maxime Coquelin <maxime.coquelin@redhat.com>
>> Sent: Tuesday, October 25, 2022 3:52 PM
>> To: Hu, Jiayu <jiayu.hu@intel.com>; Wang, YuanX <yuanx.wang@intel.com>;
>> Xia, Chenbo <chenbo.xia@intel.com>
>> Cc: dev@dpdk.org; Jiang, Cheng1 <cheng1.jiang@intel.com>; Ma, WenwuX
>> <wenwux.ma@intel.com>; He, Xingguang <xingguang.he@intel.com>;
>> Thomas Monjalon <thomas@monjalon.net>; Richardson, Bruce
>> <bruce.richardson@intel.com>; Ilya Maximets <imaximet@redhat.com>;
>> David Marchand <david.marchand@redhat.com>
>> Subject: Re: [PATCH v5] net/vhost: support asynchronous data path
>>
>> Hi Jiayu,
>>
>> On 10/25/22 04:14, Hu, Jiayu wrote:
>>> Hi Maxime,
>>>
>>> Thanks for your comments. Please see replies inline.
>>>
>>>> -----Original Message-----
>>>> From: Maxime Coquelin <maxime.coquelin@redhat.com>
>>>> Sent: Monday, October 24, 2022 5:08 PM
>>>> To: Wang, YuanX <yuanx.wang@intel.com>; Xia, Chenbo
>>>> <chenbo.xia@intel.com>
>>>> Cc: dev@dpdk.org; Hu, Jiayu <jiayu.hu@intel.com>; Jiang, Cheng1
>>>> <cheng1.jiang@intel.com>; Ma, WenwuX <wenwux.ma@intel.com>; He,
>>>> Xingguang <xingguang.he@intel.com>
>>>> Subject: Re: [PATCH v5] net/vhost: support asynchronous data path
>>>>
>>>> Hi Yuan,
>>>>
>>>> Please fix your system for the next times, your patch is dated
>>>> several hours in the future.
>>>>
>>>> On 10/24/22 17:14, Yuan Wang wrote:
>>>>> Vhost asynchronous data-path offloads packet copy from the CPU to
>>>>> the DMA engine. As a result, large packet copy can be accelerated by
>>>>> the DMA engine, and vhost can free CPU cycles for higher level
>>>>
>>>> Vhost
>>>>
>>>>> functions.
>>>>>
>>>>> In this patch, we enable asynchronous data-path for vhostpmd.
>>>>> Asynchronous data path is enabled per tx/rx queue, and users need to
>>>>> specify the DMA device used by the tx/rx queue. Each tx/rx queue
>>>>> only supports to use one DMA device, but one DMA device can be
>>>>> shared
>>>> among
>>>>> multiple tx/rx queues of different vhost PMD ports.
>>>>>
>>>>> Two PMD parameters are added:
>>>>> - dmas:	specify the used DMA device for a tx/rx queue.
>>>>> 	(Default: no queues enable asynchronous data path)
>>>>> - dma-ring-size: DMA ring size.
>>>>> 	(Default: 4096).
>>>>>
>>>>> Here is an example:
>>>>> --vdev
>>>>
>> 'eth_vhost0,iface=./s0,dmas=[txq0@0000:00.01.0;rxq0@0000:00.01.1],dma
>>>> -
>>>> ring-size=4096'
>>>>>
>>>>> Signed-off-by: Jiayu Hu <jiayu.hu@intel.com>
>>>>> Signed-off-by: Yuan Wang <yuanx.wang@intel.com>
>>>>> Signed-off-by: Wenwu Ma <wenwux.ma@intel.com>
>>>>>
>>>>> ---
>>>>> v5:
>>>>> - add error log of testpmd cmd
>>>>>
>>>>> v4:
>>>>> - add txq allow_queuing check on poll completed
>>>>> - unregister dma channel in destroy_device
>>>>> - add dma ring size minimum limit
>>>>> - fix serveral code style and logging issues
>>>>>
>>>>> v3:
>>>>> - add the API to version.map
>>>>>
>>>>> v2:
>>>>> - add missing file
>>>>> - hide async_tx_poll_completed
>>>>> - change default DMA ring size to 4096
>>>>>
>>>>> ---
>>>>>     drivers/net/vhost/meson.build     |   1 +
>>>>>     drivers/net/vhost/rte_eth_vhost.c | 512
>>>> ++++++++++++++++++++++++++++--
>>>>>     drivers/net/vhost/rte_eth_vhost.h |  15 +
>>>>>     drivers/net/vhost/version.map     |   7 +
>>>>>     drivers/net/vhost/vhost_testpmd.c |  67 ++++
>>>>>     5 files changed, 569 insertions(+), 33 deletions(-)
>>>>>     create mode 100644 drivers/net/vhost/vhost_testpmd.c
>>>>>
>>>>> diff --git a/drivers/net/vhost/meson.build
>>>>> b/drivers/net/vhost/meson.build index f481a3a4b8..22a0ab3a58 100644
>>>>> --- a/drivers/net/vhost/meson.build
>>>>> +++ b/drivers/net/vhost/meson.build
>>>>> @@ -9,4 +9,5 @@ endif
>>>>>
>>>>>     deps += 'vhost'
>>>>>     sources = files('rte_eth_vhost.c')
>>>>> +testpmd_sources = files('vhost_testpmd.c')
>>>>>     headers = files('rte_eth_vhost.h') diff --git
>>>>> a/drivers/net/vhost/rte_eth_vhost.c
>>>>> b/drivers/net/vhost/rte_eth_vhost.c
>>>>> index b152279fac..80cd9c8d92 100644
>>>>> --- a/drivers/net/vhost/rte_eth_vhost.c
>>>>> +++ b/drivers/net/vhost/rte_eth_vhost.c
>>>>> @@ -7,6 +7,7 @@
>>>>>     #include <pthread.h>
>>>>>     #include <stdbool.h>
>>>>>     #include <sys/epoll.h>
>>>>> +#include <ctype.h>
>>>>>
>>>>>     #include <rte_mbuf.h>
>>>>>     #include <ethdev_driver.h>
>>>>> @@ -18,6 +19,8 @@
>>>>>     #include <rte_kvargs.h>
>>>>>     #include <rte_vhost.h>
>>>>>     #include <rte_spinlock.h>
>>>>> +#include <rte_vhost_async.h>
>>>>> +#include <rte_dmadev.h>
>>>>>
>>>>>     #include "rte_eth_vhost.h"
>>>>>
>>>>> @@ -37,8 +40,15 @@ enum {VIRTIO_RXQ, VIRTIO_TXQ, VIRTIO_QNUM};
>>>>>     #define ETH_VHOST_LINEAR_BUF		"linear-buffer"
>>>>>     #define ETH_VHOST_EXT_BUF		"ext-buffer"
>>>>>     #define ETH_VHOST_LEGACY_OL_FLAGS	"legacy-ol-flags"
>>>>> +#define ETH_VHOST_DMA_ARG		"dmas"
>>>>> +#define ETH_VHOST_DMA_RING_SIZE		"dma-ring-size"
>>>>>     #define VHOST_MAX_PKT_BURST 32
>>>>>
>>>>> +#define INVALID_DMA_ID		-1
>>>>> +#define DEFAULT_DMA_RING_SIZE	4096
>>>>> +/* Minimum package size is 64, dma ring size should be greater than 32
>> */
>>>>> +#define MINIMUM_DMA_RING_SIZE	64
>>>>
>>>> Why? Is that related to Intel HW?
>>>
>>> No, it is for TCP/UDP tests. The max TCP/UDP length is 64KB, so one
>>> packet needs 32 pktmbufs. If we set DMA ring size to 32, it's possible
>>> that vhost cannot enqueue/dequeue one packet, as there may be some
>>> control packets mixed and DMA ring full will cause enqueue/dequeue the
>>> packet failed. So the recommend minimal DMA ring size is > 32.
>>
>> I guess it depends on the mbuf size, doesn't it?
>> I'm not against having a default value, but we need to understand the
>> rationale by just reading the code and not having to ask the author.
> 
> Sure, we will remove the MINIMUM_DMA_RING_SIZE  macro and give more
> explanation for DEFAULT_DMA_RING_SIZE.
> 
>>
>>>
>>> We can remove the macro, but add one comment to suggest the DMA ring
>>> size.
>>>>
>>>>> +
>>>>>     static const char *valid_arguments[] = {
>>>>>     	ETH_VHOST_IFACE_ARG,
>>>>>     	ETH_VHOST_QUEUES_ARG,
>>>>> @@ -49,6 +59,8 @@ static const char *valid_arguments[] = {
>>>>>     	ETH_VHOST_LINEAR_BUF,
>>>>>     	ETH_VHOST_EXT_BUF,
>>>>>     	ETH_VHOST_LEGACY_OL_FLAGS,
>>>>> +	ETH_VHOST_DMA_ARG,
>>>>> +	ETH_VHOST_DMA_RING_SIZE,
>>>>>     	NULL
>>>>>     };
>>>>>
>>>>> @@ -80,8 +92,39 @@ struct vhost_queue {
>>>>>     	struct vhost_stats stats;
>>>>>     	int intr_enable;
>>>>>     	rte_spinlock_t intr_lock;
>>>>> +
>>>>> +	/* Flag of enabling async data path */
>>>>> +	bool async_register;
>>>>> +	/* DMA device ID */
>>>>> +	int16_t dma_id;
>>>>> +	/**
>>>>> +	 * For a Rx queue, "txq" points to its peer Tx queue.
>>>>> +	 * For a Tx queue, "txq" is never used.
>>>>> +	 */
>>>>> +	struct vhost_queue *txq;
>>>>> +	/* Array to keep DMA completed packets */
>>>>> +	struct rte_mbuf *cmpl_pkts[VHOST_MAX_PKT_BURST];
>>>>>     };
>>>>>
>>>>> +struct dma_input_info {
>>>>> +	int16_t dmas[RTE_MAX_QUEUES_PER_PORT * 2];
>>>>> +	uint16_t dma_ring_size;
>>>>> +};
>>>>> +
>>>>> +static int16_t configured_dmas[RTE_DMADEV_DEFAULT_MAX];
>>>>> +static int dma_count;
>>>>> +
>>>>> +/**
>>>>> + * By default, its Rx path to call
>>>>> +rte_vhost_poll_enqueue_completed() for
>>>> enqueue operations.
>>>>> + * However, Rx function is never been called in testpmd "txonly"
>>>>> +mode, thus causing virtio
>>>>> + * cannot receive DMA completed packets. To make txonly mode work
>>>>> +correctly, we provide a
>>>>> + * command in testpmd to call rte_vhost_poll_enqueue_completed() in
>>>>> +Tx
>>>> path.
>>>>> + *
>>>>> + * When set async_tx_poll_completed to true, Tx path calls
>>>>> +rte_vhost_poll_enqueue_completed();
>>>>> + * otherwise, Rx path calls it.
>>>>> + */
>>>>> +bool async_tx_poll_completed;
>>>>> +
>>>>>     struct pmd_internal {
>>>>>     	rte_atomic32_t dev_attached;
>>>>>     	char *iface_name;
>>>>> @@ -94,6 +137,10 @@ struct pmd_internal {
>>>>>     	bool vlan_strip;
>>>>>     	bool rx_sw_csum;
>>>>>     	bool tx_sw_csum;
>>>>> +	struct {
>>>>> +		int16_t dma_id;
>>>>> +		bool async_register;
>>>>> +	} queue_dmas[RTE_MAX_QUEUES_PER_PORT * 2];
>>>>>     };
>>>>>
>>>>>     struct internal_list {
>>>>> @@ -124,6 +171,17 @@ struct rte_vhost_vring_state {
>>>>>
>>>>>     static struct rte_vhost_vring_state
>>>>> *vring_states[RTE_MAX_ETHPORTS];
>>>>>
>>>>> +static bool
>>>>> +dma_is_configured(int16_t dma_id)
>>>>> +{
>>>>> +	int i;
>>>>> +
>>>>> +	for (i = 0; i < dma_count; i++)
>>>>> +		if (configured_dmas[i] == dma_id)
>>>>> +			return true;
>>>>> +	return false;
>>>>> +}
>>>>> +
>>>>>     static int
>>>>>     vhost_dev_xstats_reset(struct rte_eth_dev *dev)
>>>>>     {
>>>>> @@ -396,15 +454,27 @@ vhost_dev_rx_sw_csum(struct rte_mbuf
>> *mbuf)
>>>>>     	mbuf->ol_flags |= RTE_MBUF_F_RX_L4_CKSUM_GOOD;
>>>>>     }
>>>>>
>>>>> +static inline void
>>>>> +vhost_tx_free_completed(int vid, uint16_t virtqueue_id, int16_t dma_id,
>>>>> +		struct rte_mbuf **pkts, uint16_t count) {
>>>>> +	uint16_t i, ret;
>>>>> +
>>>>> +	ret = rte_vhost_poll_enqueue_completed(vid, virtqueue_id, pkts,
>>>> count, dma_id, 0);
>>>>> +	for (i = 0; likely(i < ret); i++)
>>>>> +		rte_pktmbuf_free(pkts[i]);
>>>>> +}
>>>>> +
>>>>>     static uint16_t
>>>>>     eth_vhost_rx(void *q, struct rte_mbuf **bufs, uint16_t nb_bufs)
>>>>>     {
>>>>>     	struct vhost_queue *r = q;
>>>>>     	uint16_t i, nb_rx = 0;
>>>>>     	uint16_t nb_receive = nb_bufs;
>>>>> +	uint16_t nb_pkts, num;
>>>>>
>>>>>     	if (unlikely(rte_atomic32_read(&r->allow_queuing) == 0))
>>>>> -		return 0;
>>>>> +		goto tx_poll;
>>>>>
>>>>>     	rte_atomic32_set(&r->while_queuing, 1);
>>>>>
>>>>> @@ -412,19 +482,32 @@ eth_vhost_rx(void *q, struct rte_mbuf **bufs,
>>>> uint16_t nb_bufs)
>>>>>     		goto out;
>>>>>
>>>>>     	/* Dequeue packets from guest TX queue */
>>>>> -	while (nb_receive) {
>>>>> -		uint16_t nb_pkts;
>>>>> -		uint16_t num = (uint16_t)RTE_MIN(nb_receive,
>>>>> -						 VHOST_MAX_PKT_BURST);
>>>>> -
>>>>> -		nb_pkts = rte_vhost_dequeue_burst(r->vid, r->virtqueue_id,
>>>>> -						  r->mb_pool, &bufs[nb_rx],
>>>>> -						  num);
>>>>> -
>>>>> -		nb_rx += nb_pkts;
>>>>> -		nb_receive -= nb_pkts;
>>>>> -		if (nb_pkts < num)
>>>>> -			break;
>>>>> +	if (!r->async_register) {
>>>>> +		while (nb_receive) {
>>>>> +			num = (uint16_t)RTE_MIN(nb_receive,
>>>> VHOST_MAX_PKT_BURST);
>>>>> +			nb_pkts = rte_vhost_dequeue_burst(r->vid, r-
>>>>> virtqueue_id,
>>>>> +						r->mb_pool, &bufs[nb_rx],
>>>>> +						num);
>>>>> +
>>>>> +			nb_rx += nb_pkts;
>>>>> +			nb_receive -= nb_pkts;
>>>>> +			if (nb_pkts < num)
>>>>> +				break;
>>>>> +		}
>>>>> +	} else {
>>>>> +		int nr_inflight;
>>>>> +
>>>>> +		while (nb_receive) {
>>>>> +			num = (uint16_t)RTE_MIN(nb_receive,
>>>> VHOST_MAX_PKT_BURST);
>>>>> +			nb_pkts = rte_vhost_async_try_dequeue_burst(r-
>>>>> vid, r->virtqueue_id,
>>>>> +						r->mb_pool, &bufs[nb_rx],
>>>> num, &nr_inflight,
>>>>> +						r->dma_id, 0);
>>>>> +
>>>>> +			nb_rx += nb_pkts;
>>>>> +			nb_receive -= nb_pkts;
>>>>> +			if (nb_pkts < num)
>>>>> +				break;
>>>>> +		}
>>>>>     	}
>>>>>
>>>>>     	r->stats.pkts += nb_rx;
>>>>> @@ -445,6 +528,17 @@ eth_vhost_rx(void *q, struct rte_mbuf **bufs,
>>>> uint16_t nb_bufs)
>>>>>     out:
>>>>>     	rte_atomic32_set(&r->while_queuing, 0);
>>>>>
>>>>> +tx_poll:
>>>>> +	/**
>>>>> +	 * Poll and free completed packets for the virtqueue of Tx queue.
>>>>> +	 * Note that we access Tx queue's virtqueue, which is protected
>>>>> +	 * by vring lock.
>>>>> +	 */
>>>>> +	if (r->txq->async_register && !async_tx_poll_completed &&
>>>>> +			rte_atomic32_read(&r->txq->allow_queuing) == 1)
>>>>> +		vhost_tx_free_completed(r->vid, r->txq->virtqueue_id, r-
>>>>> txq->dma_id,
>>>>> +				r->cmpl_pkts, VHOST_MAX_PKT_BURST);
>>>>> +
>>>>>     	return nb_rx;
>>>>>     }
>>>>>
>>>>> @@ -456,6 +550,7 @@ eth_vhost_tx(void *q, struct rte_mbuf **bufs,
>>>> uint16_t nb_bufs)
>>>>>     	uint16_t nb_send = 0;
>>>>>     	uint64_t nb_bytes = 0;
>>>>>     	uint64_t nb_missed = 0;
>>>>> +	uint16_t nb_pkts, num;
>>>>>
>>>>>     	if (unlikely(rte_atomic32_read(&r->allow_queuing) == 0))
>>>>>     		return 0;
>>>>> @@ -486,31 +581,49 @@ eth_vhost_tx(void *q, struct rte_mbuf **bufs,
>>>> uint16_t nb_bufs)
>>>>>     	}
>>>>>
>>>>>     	/* Enqueue packets to guest RX queue */
>>>>> -	while (nb_send) {
>>>>> -		uint16_t nb_pkts;
>>>>> -		uint16_t num = (uint16_t)RTE_MIN(nb_send,
>>>>> -						 VHOST_MAX_PKT_BURST);
>>>>> +	if (!r->async_register) {
>>>>> +		while (nb_send) {
>>>>> +			num = (uint16_t)RTE_MIN(nb_send,
>>>> VHOST_MAX_PKT_BURST);
>>>>> +			nb_pkts = rte_vhost_enqueue_burst(r->vid, r-
>>>>> virtqueue_id,
>>>>> +						&bufs[nb_tx], num);
>>>>> +
>>>>> +			nb_tx += nb_pkts;
>>>>> +			nb_send -= nb_pkts;
>>>>> +			if (nb_pkts < num)
>>>>> +				break;
>>>>> +		}
>>>>>
>>>>> -		nb_pkts = rte_vhost_enqueue_burst(r->vid, r->virtqueue_id,
>>>>> -						  &bufs[nb_tx], num);
>>>>> +		for (i = 0; likely(i < nb_tx); i++) {
>>>>> +			nb_bytes += bufs[i]->pkt_len;
>>>>> +			rte_pktmbuf_free(bufs[i]);
>>>>> +		}
>>>>>
>>>>> -		nb_tx += nb_pkts;
>>>>> -		nb_send -= nb_pkts;
>>>>> -		if (nb_pkts < num)
>>>>> -			break;
>>>>> -	}
>>>>> +	} else {
>>>>> +		while (nb_send) {
>>>>> +			num = (uint16_t)RTE_MIN(nb_send,
>>>> VHOST_MAX_PKT_BURST);
>>>>> +			nb_pkts = rte_vhost_submit_enqueue_burst(r->vid,
>>>> r->virtqueue_id,
>>>>> +							&bufs[nb_tx], num, r-
>>>>> dma_id, 0);
>>>>> +
>>>>> +			nb_tx += nb_pkts;
>>>>> +			nb_send -= nb_pkts;
>>>>> +			if (nb_pkts < num)
>>>>> +				break;
>>>>> +		}
>>>>>
>>>>> -	for (i = 0; likely(i < nb_tx); i++)
>>>>> -		nb_bytes += bufs[i]->pkt_len;
>>>>> +		for (i = 0; likely(i < nb_tx); i++)
>>>>> +			nb_bytes += bufs[i]->pkt_len;
>>>>>
>>>>> -	nb_missed = nb_bufs - nb_tx;
>>>>> +		if (unlikely(async_tx_poll_completed)) {
>>>>> +			vhost_tx_free_completed(r->vid, r->virtqueue_id, r-
>>>>> dma_id, r->cmpl_pkts,
>>>>> +					VHOST_MAX_PKT_BURST);
>>>>> +		}
>>>>> +	}
>>>>>
>>>>> +	nb_missed = nb_bufs - nb_tx;
>>>>>     	r->stats.pkts += nb_tx;
>>>>>     	r->stats.bytes += nb_bytes;
>>>>>     	r->stats.missed_pkts += nb_missed;
>>>>>
>>>>> -	for (i = 0; likely(i < nb_tx); i++)
>>>>> -		rte_pktmbuf_free(bufs[i]);
>>>>>     out:
>>>>>     	rte_atomic32_set(&r->while_queuing, 0);
>>>>>
>>>>> @@ -798,6 +911,8 @@ queue_setup(struct rte_eth_dev *eth_dev, struct
>>>> pmd_internal *internal)
>>>>>     		vq->vid = internal->vid;
>>>>>     		vq->internal = internal;
>>>>>     		vq->port = eth_dev->data->port_id;
>>>>> +		if (i < eth_dev->data->nb_tx_queues)
>>>>> +			vq->txq = eth_dev->data->tx_queues[i];
>>>>>     	}
>>>>>     	for (i = 0; i < eth_dev->data->nb_tx_queues; i++) {
>>>>>     		vq = eth_dev->data->tx_queues[i]; @@ -878,6 +993,30 @@
>>>>> new_device(int vid)
>>>>>     	return 0;
>>>>>     }
>>>>>
>>>>> +static inline void
>>>>> +async_clear_virtqueue(int vid, uint16_t virtqueue_id, int16_t
>>>>> +dma_id) {
>>>>> +	struct rte_mbuf *pkts[VHOST_MAX_PKT_BURST];
>>>>> +	uint16_t i, ret, nr_done = 0;
>>>>> +
>>>>> +	if (vid == -1)
>>>>> +		return;
>>>>> +
>>>>> +	while (rte_vhost_async_get_inflight(vid, virtqueue_id) > 0) {
>>>>> +		ret = rte_vhost_clear_queue(vid, virtqueue_id, pkts,
>>>> VHOST_MAX_PKT_BURST, dma_id,
>>>>> +				0);
>>>>> +		for (i = 0; i < ret ; i++)
>>>>> +			rte_pktmbuf_free(pkts[i]);
>>>>> +
>>>>> +		nr_done += ret;
>>>>> +	}
>>>>> +	VHOST_LOG(INFO, "Completed %u pkts for vid-%u vring-%u\n",
>>>> nr_done,
>>>>> +vid, virtqueue_id);
>>>>> +
>>>>> +	if (rte_vhost_async_channel_unregister(vid, virtqueue_id))
>>>>> +		VHOST_LOG(ERR, "Failed to unregister async for vid-%u
>>>> vring-%u\n", vid,
>>>>> +				virtqueue_id);
>>>>> +}
>>>>> +
>>>>>     static void
>>>>>     destroy_device(int vid)
>>>>>     {
>>>>> @@ -908,13 +1047,27 @@ destroy_device(int vid)
>>>>>     			vq = eth_dev->data->rx_queues[i];
>>>>>     			if (!vq)
>>>>>     				continue;
>>>>> +			if (vq->async_register) {
>>>>> +				async_clear_virtqueue(vq->vid, vq-
>>>>> virtqueue_id,
>>>>> +							vq->dma_id);
>>>>> +				vq->async_register = false;
>>>>> +				internal->queue_dmas[vq-
>>>>> virtqueue_id].async_register = false;
>>>>> +			}
>>>>>     			vq->vid = -1;
>>>>> +
>>>>>     		}
>>>>>     		for (i = 0; i < eth_dev->data->nb_tx_queues; i++) {
>>>>>     			vq = eth_dev->data->tx_queues[i];
>>>>>     			if (!vq)
>>>>>     				continue;
>>>>> +			if (vq->async_register) {
>>>>> +				async_clear_virtqueue(vq->vid, vq-
>>>>> virtqueue_id,
>>>>> +							vq->dma_id);
>>>>> +				vq->async_register = false;
>>>>> +				internal->queue_dmas[vq-
>>>>> virtqueue_id].async_register = false;
>>>>> +			}
>>>>>     			vq->vid = -1;
>>>>> +
>>>>>     		}
>>>>>     	}
>>>>>
>>>>> @@ -983,6 +1136,9 @@ vring_state_changed(int vid, uint16_t vring,
>>>>> int
>>>> enable)
>>>>>     	struct rte_vhost_vring_state *state;
>>>>>     	struct rte_eth_dev *eth_dev;
>>>>>     	struct internal_list *list;
>>>>> +	struct vhost_queue *queue;
>>>>> +	struct pmd_internal *internal;
>>>>> +	int qid;
>>>>>     	char ifname[PATH_MAX];
>>>>>
>>>>>     	rte_vhost_get_ifname(vid, ifname, sizeof(ifname)); @@ -1011,6
>>>>> +1167,65 @@ vring_state_changed(int vid, uint16_t vring, int enable)
>>>>>
>>>>>     	update_queuing_status(eth_dev, false);
>>>>>
>>>>> +	qid = vring / VIRTIO_QNUM;
>>>>> +	if (vring % VIRTIO_QNUM == VIRTIO_RXQ)
>>>>> +		queue = eth_dev->data->tx_queues[qid];
>>>>> +	else
>>>>> +		queue = eth_dev->data->rx_queues[qid];
>>>>> +
>>>>> +	if (!queue)
>>>>> +		goto skip;
>>>>> +
>>>>> +	internal = eth_dev->data->dev_private;
>>>>> +
>>>>> +	/* Register async data path for the queue assigned valid DMA
>>>>> +device
>>>> */
>>>>> +	if (internal->queue_dmas[queue->virtqueue_id].dma_id ==
>>>> INVALID_DMA_ID)
>>>>> +		goto skip;
>>>>> +
>>>>> +	if (enable && !queue->async_register) {
>>>>> +		if (rte_vhost_async_channel_register_thread_unsafe(vid,
>>>> vring)) {
>>>>> +			VHOST_LOG(ERR, "Failed to register async for vid-%u
>>>> vring-%u!\n", vid,
>>>>> +					vring);
>>>>> +			return -1;
>>>>> +		}
>>>>> +
>>>>> +		queue->async_register = true;
>>>>> +		internal->queue_dmas[vring].async_register = true;
>>>>> +
>>>>> +		VHOST_LOG(INFO, "Succeed to register async for vid-%u
>>>> vring-%u\n", vid, vring);
>>>>> +	}
>>>>> +
>>>>> +	if (!enable && queue->async_register) {
>>>>> +		struct rte_mbuf *pkts[VHOST_MAX_PKT_BURST];
>>>>> +		uint16_t ret, i, nr_done = 0;
>>>>> +		uint16_t dma_id = queue->dma_id;
>>>>> +
>>>>> +		while (rte_vhost_async_get_inflight_thread_unsafe(vid,
>>>> vring) > 0) {
>>>>> +			ret = rte_vhost_clear_queue_thread_unsafe(vid,
>>>> vring, pkts,
>>>>> +					VHOST_MAX_PKT_BURST, dma_id, 0);
>>>>> +
>>>>> +			for (i = 0; i < ret ; i++)
>>>>> +				rte_pktmbuf_free(pkts[i]);
>>>>> +
>>>>> +			nr_done += ret;
>>>>> +		}
>>>>> +
>>>>> +		VHOST_LOG(INFO, "Completed %u in-flight pkts for vid-%u
>>>> vring-%u\n", nr_done, vid,
>>>>> +				vring);
>>>>> +
>>>>> +		if (rte_vhost_async_channel_unregister_thread_unsafe(vid,
>>>> vring)) {
>>>>> +			VHOST_LOG(ERR, "Failed to unregister async for vid-
>>>> %u vring-%u\n", vid,
>>>>> +					vring);
>>>>> +			return -1;
>>>>> +		}
>>>>> +
>>>>> +		queue->async_register = false;
>>>>> +		internal->queue_dmas[vring].async_register = false;
>>>>> +
>>>>> +		VHOST_LOG(INFO, "Succeed to unregister async for vid-%u
>>>> vring-%u\n", vid, vring);
>>>>> +	}
>>>>> +
>>>>> +skip:
>>>>>     	VHOST_LOG(INFO, "vring%u is %s\n",
>>>>>     			vring, enable ? "enabled" : "disabled");
>>>>>
>>>>> @@ -1159,6 +1374,12 @@
>> rte_eth_vhost_get_vid_from_port_id(uint16_t
>>>> port_id)
>>>>>     	return vid;
>>>>>     }
>>>>>
>>>>> +void
>>>>> +rte_eth_vhost_async_tx_poll_completed(bool enable) {
>>>>> +	async_tx_poll_completed = enable;
>>>>> +}
>>>>> +
>>>>>     static int
>>>>>     eth_dev_configure(struct rte_eth_dev *dev)
>>>>>     {
>>>>> @@ -1220,6 +1441,7 @@ eth_dev_close(struct rte_eth_dev *dev)
>>>>>     {
>>>>>     	struct pmd_internal *internal;
>>>>>     	struct internal_list *list;
>>>>> +	struct vhost_queue *queue;
>>>>>     	unsigned int i, ret;
>>>>>
>>>>>     	if (rte_eal_process_type() != RTE_PROC_PRIMARY) @@ -1233,6
>>>> +1455,25
>>>>> @@ eth_dev_close(struct rte_eth_dev *dev)
>>>>>
>>>>>     	list = find_internal_resource(internal->iface_name);
>>>>>     	if (list) {
>>>>> +		/* Make sure all in-flight packets are completed before
>>>> destroy vhost */
>>>>> +		if (dev->data->rx_queues) {
>>>>> +			for (i = 0; i < dev->data->nb_rx_queues; i++) {
>>>>> +				queue = dev->data->rx_queues[i];
>>>>> +				if (queue->async_register)
>>>>> +					async_clear_virtqueue(queue->vid,
>>>> queue->virtqueue_id,
>>>>> +							queue->dma_id);
>>>>> +			}
>>>>> +		}
>>>>> +
>>>>> +		if (dev->data->tx_queues) {
>>>>> +			for (i = 0; i < dev->data->nb_tx_queues; i++) {
>>>>> +				queue = dev->data->tx_queues[i];
>>>>> +				if (queue->async_register)
>>>>> +					async_clear_virtqueue(queue->vid,
>>>> queue->virtqueue_id,
>>>>> +							queue->dma_id);
>>>>> +			}
>>>>> +		}
>>>>> +
>>>>>     		rte_vhost_driver_unregister(internal->iface_name);
>>>>>     		pthread_mutex_lock(&internal_list_lock);
>>>>>     		TAILQ_REMOVE(&internal_list, list, next); @@ -1267,6
>>>> +1508,7 @@
>>>>> eth_rx_queue_setup(struct rte_eth_dev *dev, uint16_t rx_queue_id,
>>>>>     		   struct rte_mempool *mb_pool)
>>>>>     {
>>>>>     	struct vhost_queue *vq;
>>>>> +	struct pmd_internal *internal = dev->data->dev_private;
>>>>>
>>>>>     	vq = rte_zmalloc_socket(NULL, sizeof(struct vhost_queue),
>>>>>     			RTE_CACHE_LINE_SIZE, socket_id); @@ -1277,6
>> +1519,8 @@
>>>>> eth_rx_queue_setup(struct rte_eth_dev *dev, uint16_t rx_queue_id,
>>>>>
>>>>>     	vq->mb_pool = mb_pool;
>>>>>     	vq->virtqueue_id = rx_queue_id * VIRTIO_QNUM + VIRTIO_TXQ;
>>>>> +	vq->async_register = internal->queue_dmas[vq-
>>>>> virtqueue_id].async_register;
>>>>> +	vq->dma_id = internal->queue_dmas[vq->virtqueue_id].dma_id;
>>>>>     	rte_spinlock_init(&vq->intr_lock);
>>>>>     	dev->data->rx_queues[rx_queue_id] = vq;
>>>>>
>>>>> @@ -1290,6 +1534,7 @@ eth_tx_queue_setup(struct rte_eth_dev *dev,
>>>> uint16_t tx_queue_id,
>>>>>     		   const struct rte_eth_txconf *tx_conf __rte_unused)
>>>>>     {
>>>>>     	struct vhost_queue *vq;
>>>>> +	struct pmd_internal *internal = dev->data->dev_private;
>>>>>
>>>>>     	vq = rte_zmalloc_socket(NULL, sizeof(struct vhost_queue),
>>>>>     			RTE_CACHE_LINE_SIZE, socket_id); @@ -1299,6
>> +1544,8 @@
>>>>> eth_tx_queue_setup(struct rte_eth_dev *dev,
>>>> uint16_t tx_queue_id,
>>>>>     	}
>>>>>
>>>>>     	vq->virtqueue_id = tx_queue_id * VIRTIO_QNUM + VIRTIO_RXQ;
>>>>> +	vq->async_register = internal->queue_dmas[vq-
>>>>> virtqueue_id].async_register;
>>>>> +	vq->dma_id = internal->queue_dmas[vq->virtqueue_id].dma_id;
>>>>>     	rte_spinlock_init(&vq->intr_lock);
>>>>>     	dev->data->tx_queues[tx_queue_id] = vq;
>>>>>
>>>>> @@ -1509,13 +1756,14 @@ static const struct eth_dev_ops ops = {
>>>>>     static int
>>>>>     eth_dev_vhost_create(struct rte_vdev_device *dev, char *iface_name,
>>>>>     	int16_t queues, const unsigned int numa_node, uint64_t flags,
>>>>> -	uint64_t disable_flags)
>>>>> +	uint64_t disable_flags, struct dma_input_info *dma_input)
>>>>>     {
>>>>>     	const char *name = rte_vdev_device_name(dev);
>>>>>     	struct rte_eth_dev_data *data;
>>>>>     	struct pmd_internal *internal = NULL;
>>>>>     	struct rte_eth_dev *eth_dev = NULL;
>>>>>     	struct rte_ether_addr *eth_addr = NULL;
>>>>> +	int i;
>>>>>
>>>>>     	VHOST_LOG(INFO, "Creating VHOST-USER backend on numa
>>>> socket %u\n",
>>>>>     		numa_node);
>>>>> @@ -1564,6 +1812,12 @@ eth_dev_vhost_create(struct rte_vdev_device
>>>> *dev, char *iface_name,
>>>>>     	eth_dev->rx_pkt_burst = eth_vhost_rx;
>>>>>     	eth_dev->tx_pkt_burst = eth_vhost_tx;
>>>>>
>>>>> +	for (i = 0; i < RTE_MAX_QUEUES_PER_PORT * 2; i++) {
>>>>> +		/* Invalid DMA ID indicates the queue does not want to
>>>> enable async data path */
>>>>> +		internal->queue_dmas[i].dma_id = dma_input->dmas[i];
>>>>> +		internal->queue_dmas[i].async_register = false;
>>>>> +	}
>>>>> +
>>>>>     	rte_eth_dev_probing_finish(eth_dev);
>>>>>     	return 0;
>>>>>
>>>>> @@ -1603,6 +1857,155 @@ open_int(const char *key __rte_unused,
>> const
>>>> char *value, void *extra_args)
>>>>>     	return 0;
>>>>>     }
>>>>>
>>>>> +static int
>>>>> +init_dma(int16_t dma_id, uint16_t ring_size) {
>>>>> +	struct rte_dma_info info;
>>>>> +	struct rte_dma_conf dev_config = { .nb_vchans = 1 };
>>>>> +	struct rte_dma_vchan_conf qconf = {
>>>>> +		.direction = RTE_DMA_DIR_MEM_TO_MEM,
>>>>> +	};
>>>>> +	int ret = 0;
>>>>> +
>>>>> +	if (dma_is_configured(dma_id))
>>>>> +		goto out;
>>>>> +
>>>>> +	if (rte_dma_info_get(dma_id, &info) != 0) {
>>>>> +		VHOST_LOG(ERR, "dma %u get info failed\n", dma_id);
>>>>> +		ret = -1;
>>>>> +		goto out;
>>>>> +	}
>>>>> +
>>>>> +	if (info.max_vchans < 1) {
>>>>> +		VHOST_LOG(ERR, "No channels available on dma %d\n",
>>>> dma_id);
>>>>> +		ret = -1;
>>>>> +		goto out;
>>>>> +	}
>>>>> +
>>>>> +	if (rte_dma_configure(dma_id, &dev_config) != 0) {
>>>>> +		VHOST_LOG(ERR, "dma %u configure failed\n", dma_id);
>>>>> +		ret = -1;
>>>>> +		goto out;
>>>>> +	}
>>>>> +
>>>>> +	rte_dma_info_get(dma_id, &info);
>>>>> +	if (info.nb_vchans != 1) {
>>>>> +		VHOST_LOG(ERR, "dma %u has no queues\n", dma_id);
>>>>> +		ret = -1;
>>>>> +		goto out;
>>>>> +	}
>>>>> +
>>>>> +	ring_size = RTE_MAX(ring_size, MINIMUM_DMA_RING_SIZE);
>>>>> +	ring_size = RTE_MAX(ring_size, info.min_desc);
>>>>> +	qconf.nb_desc = RTE_MIN(ring_size, info.max_desc);
>>>>> +	if (rte_dma_vchan_setup(dma_id, 0, &qconf) != 0) {
>>>>> +		VHOST_LOG(ERR, "dma %u queue setup failed\n", dma_id);
>>>>> +		ret = -1;
>>>>> +		goto out;
>>>>> +	}
>>>>> +
>>>>> +	if (rte_dma_start(dma_id) != 0) {
>>>>> +		VHOST_LOG(ERR, "dma %u start failed\n", dma_id);
>>>>> +		ret = -1;
>>>>> +		goto out;
>>>>> +	}
>>>>> +
>>>>> +	configured_dmas[dma_count++] = dma_id;
>>>>> +
>>>>> +out:
>>>>> +	return ret;
>>>>> +}
>>>>> +
>>>>> +static int
>>>>> +open_dma(const char *key __rte_unused, const char *value, void
>>>>> +*extra_args) {
>>>>> +	struct dma_input_info *dma_input = extra_args;
>>>>> +	char *input = strndup(value, strlen(value) + 1);
>>>>> +	char *addrs = input;
>>>>> +	char *ptrs[2];
>>>>> +	char *start, *end, *substr;
>>>>> +	uint16_t qid, virtqueue_id;
>>>>> +	int16_t dma_id;
>>>>> +	int i, ret = 0;
>>>>> +
>>>>> +	while (isblank(*addrs))
>>>>> +		addrs++;
>>>>> +	if (*addrs == '\0') {
>>>>> +		VHOST_LOG(ERR, "No input DMA addresses\n");
>>>>> +		ret = -1;
>>>>> +		goto out;
>>>>> +	}
>>>>> +
>>>>> +	/* process DMA devices within bracket. */
>>>>> +	addrs++;
>>>>> +	substr = strtok(addrs, ";]");
>>>>> +	if (!substr) {
>>>>> +		VHOST_LOG(ERR, "No input DMA addresse\n");
>>>>> +		ret = -1;
>>>>> +		goto out;
>>>>> +	}
>>>>> +
>>>>> +	do {
>>>>> +		rte_strsplit(substr, strlen(substr), ptrs, 2, '@');
>>>>> +
>>>>> +		char *txq, *rxq;
>>>>> +		bool is_txq;
>>>>> +
>>>>> +		txq = strstr(ptrs[0], "txq");
>>>>> +		rxq = strstr(ptrs[0], "rxq");
>>>>> +		if (txq == NULL && rxq == NULL) {
>>>>> +			VHOST_LOG(ERR, "Illegal queue\n");
>>>>> +			ret = -1;
>>>>> +			goto out;
>>>>> +		} else if (txq) {
>>>>> +			is_txq = true;
>>>>> +			start = txq;
>>>>> +		} else {
>>>>> +			is_txq = false;
>>>>> +			start = rxq;
>>>>> +		}
>>>>> +
>>>>> +		start += 3;
>>>>> +		qid = strtol(start, &end, 0);
>>>>> +		if (end == start) {
>>>>> +			VHOST_LOG(ERR, "No input queue ID\n");
>>>>> +			ret = -1;
>>>>> +			goto out;
>>>>> +		}
>>>>> +
>>>>> +		virtqueue_id = is_txq ? qid * 2 + VIRTIO_RXQ : qid * 2 +
>>>>> +VIRTIO_TXQ;
>>>>> +
>>>>> +		dma_id = rte_dma_get_dev_id_by_name(ptrs[1]);
>>>>> +		if (dma_id < 0) {
>>>>> +			VHOST_LOG(ERR, "Fail to find DMA device %s.\n",
>>>> ptrs[1]);
>>>>> +			ret = -1;
>>>>> +			goto out;
>>>>> +		}
>>>>> +
>>>>> +		ret = init_dma(dma_id, dma_input->dma_ring_size);
>>>>> +		if (ret != 0) {
>>>>> +			VHOST_LOG(ERR, "Fail to initialize DMA %u\n",
>>>> dma_id);
>>>>> +			ret = -1;
>>>>> +			break;
>>>>> +		}
>>>>> +
>>>>> +		dma_input->dmas[virtqueue_id] = dma_id;
>>>>> +
>>>>> +		substr = strtok(NULL, ";]");
>>>>> +	} while (substr);
>>>>> +
>>>>> +	for (i = 0; i < dma_count; i++) {
>>>>> +		if (rte_vhost_async_dma_configure(configured_dmas[i], 0) <
>>>> 0) {
>>>>> +			VHOST_LOG(ERR, "Fail to configure DMA %u to
>>>> vhost\n", configured_dmas[i]);
>>>>> +			ret = -1;
>>>>> +		}
>>>>> +	}
>>>>> +
>>>>> +out:
>>>>> +	free(input);
>>>>> +	return ret;
>>>>> +}
>>>>> +
>>>>>     static int
>>>>>     rte_pmd_vhost_probe(struct rte_vdev_device *dev)
>>>>>     {
>>>>> @@ -1621,6 +2024,10 @@ rte_pmd_vhost_probe(struct
>> rte_vdev_device
>>>> *dev)
>>>>>     	int legacy_ol_flags = 0;
>>>>>     	struct rte_eth_dev *eth_dev;
>>>>>     	const char *name = rte_vdev_device_name(dev);
>>>>> +	struct dma_input_info dma_input;
>>>>> +
>>>>> +	memset(dma_input.dmas, INVALID_DMA_ID,
>>>> sizeof(dma_input.dmas));
>>>>> +	dma_input.dma_ring_size = DEFAULT_DMA_RING_SIZE;
>>>>>
>>>>>     	VHOST_LOG(INFO, "Initializing pmd_vhost for %s\n", name);
>>>>>
>>>>> @@ -1736,6 +2143,43 @@ rte_pmd_vhost_probe(struct
>> rte_vdev_device
>>>> *dev)
>>>>>     			goto out_free;
>>>>>     	}
>>>>>
>>>>> +	if (rte_kvargs_count(kvlist, ETH_VHOST_DMA_RING_SIZE) == 1) {
>>>>> +		if (rte_kvargs_count(kvlist, ETH_VHOST_DMA_ARG) == 1) {
>>>>> +			ret = rte_kvargs_process(kvlist,
>>>> ETH_VHOST_DMA_RING_SIZE,
>>>>> +					&open_int,
>>>> &dma_input.dma_ring_size);
>>>>> +			if (ret < 0)
>>>>> +				goto out_free;
>>>>> +
>>>>> +			if (!rte_is_power_of_2(dma_input.dma_ring_size)) {
>>>>> +				dma_input.dma_ring_size =
>>>> rte_align32pow2(dma_input.dma_ring_size);
>>>>> +				VHOST_LOG(INFO, "Convert dma_ring_size to
>>>> the power of two %u\n",
>>>>> +						dma_input.dma_ring_size);
>>>>> +			}
>>>>> +		} else {
>>>>> +			VHOST_LOG(WARNING, "%s is not specified, skip to
>>>> parse %s\n",
>>>>> +					ETH_VHOST_DMA_ARG,
>>>> ETH_VHOST_DMA_RING_SIZE);
>>>>> +		}
>>>>> +	}
>>>>> +
>>>>> +	if (rte_kvargs_count(kvlist, ETH_VHOST_DMA_ARG) == 1) {
>>>>> +		if (rte_kvargs_count(kvlist, ETH_VHOST_DMA_RING_SIZE) ==
>>>> 0)
>>>>> +			VHOST_LOG(INFO, "Use default dma ring size %d\n",
>>>>> +DEFAULT_DMA_RING_SIZE);
>>>>> +
>>>>> +		ret = rte_kvargs_process(kvlist, ETH_VHOST_DMA_ARG,
>>>>> +					 &open_dma, &dma_input);
>>>>> +		if (ret < 0) {
>>>>> +			VHOST_LOG(ERR, "Failed to parse %s\n",
>>>> ETH_VHOST_DMA_ARG);
>>>>> +			goto out_free;
>>>>> +		}
>>>>> +
>>>>> +		flags |= RTE_VHOST_USER_ASYNC_COPY;
>>>>> +		/**
>>>>> +		 * Don't support live migration when enable
>>>>> +		 * DMA acceleration.
>>>>> +		 */
>>>>> +		disable_flags |= (1ULL << VHOST_F_LOG_ALL);
>>>>> +	}
>>>>> +
>>>>>     	if (legacy_ol_flags == 0)
>>>>>     		flags |= RTE_VHOST_USER_NET_COMPLIANT_OL_FLAGS;
>>>>>
>>>>> @@ -1743,7 +2187,7 @@ rte_pmd_vhost_probe(struct rte_vdev_device
>>>> *dev)
>>>>>     		dev->device.numa_node = rte_socket_id();
>>>>>
>>>>>     	ret = eth_dev_vhost_create(dev, iface_name, queues,
>>>>> -				   dev->device.numa_node, flags,
>>>> disable_flags);
>>>>> +			dev->device.numa_node, flags, disable_flags,
>>>> &dma_input);
>>>>>     	if (ret == -1)
>>>>>     		VHOST_LOG(ERR, "Failed to create %s\n", name);
>>>>>
>>>>> @@ -1787,4 +2231,6 @@
>> RTE_PMD_REGISTER_PARAM_STRING(net_vhost,
>>>>>     	"postcopy-support=<0|1> "
>>>>>     	"tso=<0|1> "
>>>>>     	"linear-buffer=<0|1> "
>>>>> -	"ext-buffer=<0|1>");
>>>>> +	"ext-buffer=<0|1> "
>>>>> +	"dma-ring-size=<int> "
>>>>> +	"dmas=[txq0@dma_addr;rxq0@dma_addr]");
>>>>> diff --git a/drivers/net/vhost/rte_eth_vhost.h
>>>>> b/drivers/net/vhost/rte_eth_vhost.h
>>>>> index 0e68b9f668..146c98803d 100644
>>>>> --- a/drivers/net/vhost/rte_eth_vhost.h
>>>>> +++ b/drivers/net/vhost/rte_eth_vhost.h
>>>>> @@ -52,6 +52,21 @@ int rte_eth_vhost_get_queue_event(uint16_t
>> port_id,
>>>>>      */
>>>>>     int rte_eth_vhost_get_vid_from_port_id(uint16_t port_id);
>>>>>
>>>>> +/**
>>>>> + * @warning
>>>>> + * @b EXPERIMENTAL: this API may change, or be removed, without
>>>>> +prior notice
>>>>> + *
>>>>> + * By default, rte_vhost_poll_enqueue_completed() is called in Rx path.
>>>>> + * This function enables Tx path, rather than Rx path, to poll
>>>>> +completed
>>>>> + * packets for vhost async enqueue operations. Note that virtio may
>>>>> +never
>>>>> + * receive DMA completed packets if there are no more Tx operations.
>>>>> + *
>>>>> + * @param enable
>>>>> + *  True indicates Tx path to call rte_vhost_poll_enqueue_completed().
>>>>> + */
>>>>> +__rte_experimental
>>>>> +void rte_eth_vhost_async_tx_poll_completed(bool enable);
>>>>> +
>>>>>     #ifdef __cplusplus
>>>>>     }
>>>>>     #endif
>>>>> diff --git a/drivers/net/vhost/version.map
>>>>> b/drivers/net/vhost/version.map index e42c89f1eb..0a40441227 100644
>>>>> --- a/drivers/net/vhost/version.map
>>>>> +++ b/drivers/net/vhost/version.map
>>>>> @@ -6,3 +6,10 @@ DPDK_23 {
>>>>>
>>>>>     	local: *;
>>>>>     };
>>>>> +
>>>>> +EXPERIMENTAL {
>>>>> +	global:
>>>>> +
>>>>> +	# added in 22.11
>>>>> +	rte_eth_vhost_async_tx_poll_completed;
>>>>
>>>> I'm not in favor of adding driver-specific API.
>>>> IMHO, you should just decide whether doing completion on Tx or Rx
>>>> path and stick with it.
>>>>
>>>> Doing completion on the Tx path not being reliable (i.e. if not other
>>>> packets are sent, last enqueued packets are not completed), I guess
>>>> only doing completion in Rx path is the right thing to do.
>>>
>>> It's good to know your thoughts. But if we remove the driver-specific
>>> API and put poll_enqueue_completed in Rx path, Testpmd txonly mode
>>> cannot work with DMA accelerated enqueue, as no one will call
>> poll_enqueue_completed.
>>> Any thoughts?
>>
>> I think it proves the async feature is not usable as it is implemented today.
>>
>> Expecting the user to know he has to select or change at runtime the tx
>> completion mode for the feature to just work (not only a performance
>> tuning) is not acceptable IMHO.
>>
>> To summarize:
>>    - By default, Tx completion are done by the Rx path so txonly mode is not
>> working (and nothing will notify the user).
>>    - If user switch to Tx completion are done by the Tx path, last packet will
>> never be completed.
> 
> Another way is to call rte_vhost_poll_enqueue_completed in both Rx and Tx
> path. In this way, we will not have the issues above, and the performance drop
> is not too much (it is ~10%, compared with calling in Tx path).
> 
> Does it make sense?

There is still the last Tx packet never being completed.

> 
>>
>> It may work for benchmark, but it is not usable in real-life.
> 
> IMHO, Vhost PMD is for benchmark purpose. No real applications use
> Vhost PMD. The motivation of enabling asynchronous data path in Vhost
> PMD is to demonstrate the performance of DMA accelerated data path
> too.

I don't think Vhost PMD is only for benchmarking purpose.
It can do the job for a lot of applications, and we've had in the past
bug reports from people/companies not involved in Vhost library
development for Vhost PMD, so this is likely being used.

>> I think that for Vhost PMD, the Virtio completions should either be
>> performed by DMA engine or by a dedicated thread.
> 
> We cannot depend on DMA engine to do completion, as there is no
> ordering guarantee on the HW. For example, given the DMA engine
> issues two updates on the used ring's index, it is possible that the second
> write completes before the first one.

I'm not sure for Intel hardware, but other vendors may offer ordering
guarantees, it should be exposed as a capability of the DMA device. If
the DMA device offers this capability, it could be used for Vhost.

> For a dedicated thread, the scalability may become the issue. Performance
> could drop due to multiple cores read/write shared data.

Ok, but it is still better than having packets stuck in the queue
because of missing Virtio completions.

> For real workload integration, I believe there are already lots of discussions
> on OVS. But for this patch, it is more as a benchmark to demonstrate the
> benefits from DMA acceleration, IMHO.

It does not bring much benefits if it is not reliable IMHO, presenting
artificial numbers because we knowingly let the possibility of having
packets stuck in the virtqueues is not a good thing.

Regards,
Maxime

> Thanks,
> Jiayu
>>
>> Regards,
>> Maxime
>>
>>>
>>> Thanks,
>>> Jiayu
>
Bruce Richardson Oct. 25, 2022, 3:44 p.m. UTC | #8
On Tue, Oct 25, 2022 at 05:33:31PM +0200, Maxime Coquelin wrote:
> 
> 
> On 10/25/22 11:15, Hu, Jiayu wrote:

> > > I think that for Vhost PMD, the Virtio completions should either be
> > > performed by DMA engine or by a dedicated thread.
> > 
> > We cannot depend on DMA engine to do completion, as there is no
> > ordering guarantee on the HW. For example, given the DMA engine
> > issues two updates on the used ring's index, it is possible that the second
> > write completes before the first one.
> 
> I'm not sure for Intel hardware, but other vendors may offer ordering
> guarantees, it should be exposed as a capability of the DMA device. If
> the DMA device offers this capability, it could be used for Vhost.
> 

While I haven't been following this discussion, this particular comment
caught my eye.

For jobs submitted via a single dmadev device, the "FENCE" flag is provided
as part of the dmadev API[1]. Obviously, if the writes come from different
dmadevs, then things are rather more complicated.

/Bruce


[1] https://doc.dpdk.org/api/rte__dmadev_8h.html#a3375e7b956b305505073c4ff035afe2f
Maxime Coquelin Oct. 25, 2022, 4:04 p.m. UTC | #9
On 10/25/22 17:44, Bruce Richardson wrote:
> On Tue, Oct 25, 2022 at 05:33:31PM +0200, Maxime Coquelin wrote:
>>
>>
>> On 10/25/22 11:15, Hu, Jiayu wrote:
> 
>>>> I think that for Vhost PMD, the Virtio completions should either be
>>>> performed by DMA engine or by a dedicated thread.
>>>
>>> We cannot depend on DMA engine to do completion, as there is no
>>> ordering guarantee on the HW. For example, given the DMA engine
>>> issues two updates on the used ring's index, it is possible that the second
>>> write completes before the first one.
>>
>> I'm not sure for Intel hardware, but other vendors may offer ordering
>> guarantees, it should be exposed as a capability of the DMA device. If
>> the DMA device offers this capability, it could be used for Vhost.
>>
> 
> While I haven't been following this discussion, this particular comment
> caught my eye.
> 
> For jobs submitted via a single dmadev device, the "FENCE" flag is provided
> as part of the dmadev API[1]. Obviously, if the writes come from different
> dmadevs, then things are rather more complicated.

Thanks for the clarification Bruce.

In the Vhost PMD case, there is a 1:1 mapping between the virtqueue and
the DMA channel, so we should be fine.

Regards,
Maxime

> /Bruce
> 
> 
> [1] https://doc.dpdk.org/api/rte__dmadev_8h.html#a3375e7b956b305505073c4ff035afe2f
>
Hu, Jiayu Oct. 26, 2022, 2:48 a.m. UTC | #10
> -----Original Message-----
> From: Maxime Coquelin <maxime.coquelin@redhat.com>
> Sent: Wednesday, October 26, 2022 12:05 AM
> To: Richardson, Bruce <bruce.richardson@intel.com>
> Cc: Hu, Jiayu <jiayu.hu@intel.com>; Wang, YuanX <yuanx.wang@intel.com>;
> Xia, Chenbo <chenbo.xia@intel.com>; dev@dpdk.org; Jiang, Cheng1
> <cheng1.jiang@intel.com>; Ma, WenwuX <wenwux.ma@intel.com>; He,
> Xingguang <xingguang.he@intel.com>; Thomas Monjalon
> <thomas@monjalon.net>; Ilya Maximets <imaximet@redhat.com>; David
> Marchand <david.marchand@redhat.com>
> Subject: Re: [PATCH v5] net/vhost: support asynchronous data path
> 
> 
> 
> On 10/25/22 17:44, Bruce Richardson wrote:
> > On Tue, Oct 25, 2022 at 05:33:31PM +0200, Maxime Coquelin wrote:
> >>
> >>
> >> On 10/25/22 11:15, Hu, Jiayu wrote:
> >
> >>>> I think that for Vhost PMD, the Virtio completions should either be
> >>>> performed by DMA engine or by a dedicated thread.
> >>>
> >>> We cannot depend on DMA engine to do completion, as there is no
> >>> ordering guarantee on the HW. For example, given the DMA engine
> >>> issues two updates on the used ring's index, it is possible that the
> >>> second write completes before the first one.
> >>
> >> I'm not sure for Intel hardware, but other vendors may offer ordering
> >> guarantees, it should be exposed as a capability of the DMA device.
> >> If the DMA device offers this capability, it could be used for Vhost.
> >>
> >
> > While I haven't been following this discussion, this particular
> > comment caught my eye.
> >
> > For jobs submitted via a single dmadev device, the "FENCE" flag is
> > provided as part of the dmadev API[1]. Obviously, if the writes come
> > from different dmadevs, then things are rather more complicated.
>

The cost of "FENCE" is significant, as it requires the HW to stop pipeline and
wait until all previous jobs completed. If ask DMA to update used ring's index,
every updating on used ring's index requires "FENCE", which will make enqueue/
dequeue become sync operation finally. "FENCE" would slow down DMA and make
DMA become the bottleneck quickly. Also, stalling HW pipeline also means waste
DMA resource. The more efficient way to maintain the ordering is by SW. I don't
think it is acceptable from performance and resource utilization perspective.

Thanks,
Jiayu

> Thanks for the clarification Bruce.
> 
> In the Vhost PMD case, there is a 1:1 mapping between the virtqueue and
> the DMA channel, so we should be fine.
> 
> Regards,
> Maxime
> 
> > /Bruce
> >
> >
> > [1]
> >
> https://doc.dpdk.org/api/rte__dmadev_8h.html#a3375e7b956b305505073c4
> ff
> > 035afe2f
> >
Maxime Coquelin Oct. 26, 2022, 5 a.m. UTC | #11
Hi Jiayu,

On 10/26/22 04:48, Hu, Jiayu wrote:
> 
> 
>> -----Original Message-----
>> From: Maxime Coquelin <maxime.coquelin@redhat.com>
>> Sent: Wednesday, October 26, 2022 12:05 AM
>> To: Richardson, Bruce <bruce.richardson@intel.com>
>> Cc: Hu, Jiayu <jiayu.hu@intel.com>; Wang, YuanX <yuanx.wang@intel.com>;
>> Xia, Chenbo <chenbo.xia@intel.com>; dev@dpdk.org; Jiang, Cheng1
>> <cheng1.jiang@intel.com>; Ma, WenwuX <wenwux.ma@intel.com>; He,
>> Xingguang <xingguang.he@intel.com>; Thomas Monjalon
>> <thomas@monjalon.net>; Ilya Maximets <imaximet@redhat.com>; David
>> Marchand <david.marchand@redhat.com>
>> Subject: Re: [PATCH v5] net/vhost: support asynchronous data path
>>
>>
>>
>> On 10/25/22 17:44, Bruce Richardson wrote:
>>> On Tue, Oct 25, 2022 at 05:33:31PM +0200, Maxime Coquelin wrote:
>>>>
>>>>
>>>> On 10/25/22 11:15, Hu, Jiayu wrote:
>>>
>>>>>> I think that for Vhost PMD, the Virtio completions should either be
>>>>>> performed by DMA engine or by a dedicated thread.
>>>>>
>>>>> We cannot depend on DMA engine to do completion, as there is no
>>>>> ordering guarantee on the HW. For example, given the DMA engine
>>>>> issues two updates on the used ring's index, it is possible that the
>>>>> second write completes before the first one.
>>>>
>>>> I'm not sure for Intel hardware, but other vendors may offer ordering
>>>> guarantees, it should be exposed as a capability of the DMA device.
>>>> If the DMA device offers this capability, it could be used for Vhost.
>>>>
>>>
>>> While I haven't been following this discussion, this particular
>>> comment caught my eye.
>>>
>>> For jobs submitted via a single dmadev device, the "FENCE" flag is
>>> provided as part of the dmadev API[1]. Obviously, if the writes come
>>> from different dmadevs, then things are rather more complicated.
>>
> 
> The cost of "FENCE" is significant, as it requires the HW to stop pipeline and
> wait until all previous jobs completed. If ask DMA to update used ring's index,
> every updating on used ring's index requires "FENCE", which will make enqueue/
> dequeue become sync operation finally. "FENCE" would slow down DMA and make
> DMA become the bottleneck quickly. Also, stalling HW pipeline also means waste
> DMA resource. The more efficient way to maintain the ordering is by SW. I don't
> think it is acceptable from performance and resource utilization perspective.

But on the other hand, there will be less cachelines sharing between the
port's Rx and Tx PMD threads. IIRC, Virtio completions by the DMA
engines was discussed but never prototyped, so hard to draw a
conclusion.

Thanks,
Maxime

> Thanks,
> Jiayu
> 
>> Thanks for the clarification Bruce.
>>
>> In the Vhost PMD case, there is a 1:1 mapping between the virtqueue and
>> the DMA channel, so we should be fine.
>>
>> Regards,
>> Maxime
>>
>>> /Bruce
>>>
>>>
>>> [1]
>>>
>> https://doc.dpdk.org/api/rte__dmadev_8h.html#a3375e7b956b305505073c4
>> ff
>>> 035afe2f
>>>
>
diff mbox series

Patch

diff --git a/drivers/net/vhost/meson.build b/drivers/net/vhost/meson.build
index f481a3a4b8..22a0ab3a58 100644
--- a/drivers/net/vhost/meson.build
+++ b/drivers/net/vhost/meson.build
@@ -9,4 +9,5 @@  endif
 
 deps += 'vhost'
 sources = files('rte_eth_vhost.c')
+testpmd_sources = files('vhost_testpmd.c')
 headers = files('rte_eth_vhost.h')
diff --git a/drivers/net/vhost/rte_eth_vhost.c b/drivers/net/vhost/rte_eth_vhost.c
index b152279fac..80cd9c8d92 100644
--- a/drivers/net/vhost/rte_eth_vhost.c
+++ b/drivers/net/vhost/rte_eth_vhost.c
@@ -7,6 +7,7 @@ 
 #include <pthread.h>
 #include <stdbool.h>
 #include <sys/epoll.h>
+#include <ctype.h>
 
 #include <rte_mbuf.h>
 #include <ethdev_driver.h>
@@ -18,6 +19,8 @@ 
 #include <rte_kvargs.h>
 #include <rte_vhost.h>
 #include <rte_spinlock.h>
+#include <rte_vhost_async.h>
+#include <rte_dmadev.h>
 
 #include "rte_eth_vhost.h"
 
@@ -37,8 +40,15 @@  enum {VIRTIO_RXQ, VIRTIO_TXQ, VIRTIO_QNUM};
 #define ETH_VHOST_LINEAR_BUF		"linear-buffer"
 #define ETH_VHOST_EXT_BUF		"ext-buffer"
 #define ETH_VHOST_LEGACY_OL_FLAGS	"legacy-ol-flags"
+#define ETH_VHOST_DMA_ARG		"dmas"
+#define ETH_VHOST_DMA_RING_SIZE		"dma-ring-size"
 #define VHOST_MAX_PKT_BURST 32
 
+#define INVALID_DMA_ID		-1
+#define DEFAULT_DMA_RING_SIZE	4096
+/* Minimum package size is 64, dma ring size should be greater than 32 */
+#define MINIMUM_DMA_RING_SIZE	64
+
 static const char *valid_arguments[] = {
 	ETH_VHOST_IFACE_ARG,
 	ETH_VHOST_QUEUES_ARG,
@@ -49,6 +59,8 @@  static const char *valid_arguments[] = {
 	ETH_VHOST_LINEAR_BUF,
 	ETH_VHOST_EXT_BUF,
 	ETH_VHOST_LEGACY_OL_FLAGS,
+	ETH_VHOST_DMA_ARG,
+	ETH_VHOST_DMA_RING_SIZE,
 	NULL
 };
 
@@ -80,8 +92,39 @@  struct vhost_queue {
 	struct vhost_stats stats;
 	int intr_enable;
 	rte_spinlock_t intr_lock;
+
+	/* Flag of enabling async data path */
+	bool async_register;
+	/* DMA device ID */
+	int16_t dma_id;
+	/**
+	 * For a Rx queue, "txq" points to its peer Tx queue.
+	 * For a Tx queue, "txq" is never used.
+	 */
+	struct vhost_queue *txq;
+	/* Array to keep DMA completed packets */
+	struct rte_mbuf *cmpl_pkts[VHOST_MAX_PKT_BURST];
 };
 
+struct dma_input_info {
+	int16_t dmas[RTE_MAX_QUEUES_PER_PORT * 2];
+	uint16_t dma_ring_size;
+};
+
+static int16_t configured_dmas[RTE_DMADEV_DEFAULT_MAX];
+static int dma_count;
+
+/**
+ * By default, its Rx path to call rte_vhost_poll_enqueue_completed() for enqueue operations.
+ * However, Rx function is never been called in testpmd "txonly" mode, thus causing virtio
+ * cannot receive DMA completed packets. To make txonly mode work correctly, we provide a
+ * command in testpmd to call rte_vhost_poll_enqueue_completed() in Tx path.
+ *
+ * When set async_tx_poll_completed to true, Tx path calls rte_vhost_poll_enqueue_completed();
+ * otherwise, Rx path calls it.
+ */
+bool async_tx_poll_completed;
+
 struct pmd_internal {
 	rte_atomic32_t dev_attached;
 	char *iface_name;
@@ -94,6 +137,10 @@  struct pmd_internal {
 	bool vlan_strip;
 	bool rx_sw_csum;
 	bool tx_sw_csum;
+	struct {
+		int16_t dma_id;
+		bool async_register;
+	} queue_dmas[RTE_MAX_QUEUES_PER_PORT * 2];
 };
 
 struct internal_list {
@@ -124,6 +171,17 @@  struct rte_vhost_vring_state {
 
 static struct rte_vhost_vring_state *vring_states[RTE_MAX_ETHPORTS];
 
+static bool
+dma_is_configured(int16_t dma_id)
+{
+	int i;
+
+	for (i = 0; i < dma_count; i++)
+		if (configured_dmas[i] == dma_id)
+			return true;
+	return false;
+}
+
 static int
 vhost_dev_xstats_reset(struct rte_eth_dev *dev)
 {
@@ -396,15 +454,27 @@  vhost_dev_rx_sw_csum(struct rte_mbuf *mbuf)
 	mbuf->ol_flags |= RTE_MBUF_F_RX_L4_CKSUM_GOOD;
 }
 
+static inline void
+vhost_tx_free_completed(int vid, uint16_t virtqueue_id, int16_t dma_id,
+		struct rte_mbuf **pkts, uint16_t count)
+{
+	uint16_t i, ret;
+
+	ret = rte_vhost_poll_enqueue_completed(vid, virtqueue_id, pkts, count, dma_id, 0);
+	for (i = 0; likely(i < ret); i++)
+		rte_pktmbuf_free(pkts[i]);
+}
+
 static uint16_t
 eth_vhost_rx(void *q, struct rte_mbuf **bufs, uint16_t nb_bufs)
 {
 	struct vhost_queue *r = q;
 	uint16_t i, nb_rx = 0;
 	uint16_t nb_receive = nb_bufs;
+	uint16_t nb_pkts, num;
 
 	if (unlikely(rte_atomic32_read(&r->allow_queuing) == 0))
-		return 0;
+		goto tx_poll;
 
 	rte_atomic32_set(&r->while_queuing, 1);
 
@@ -412,19 +482,32 @@  eth_vhost_rx(void *q, struct rte_mbuf **bufs, uint16_t nb_bufs)
 		goto out;
 
 	/* Dequeue packets from guest TX queue */
-	while (nb_receive) {
-		uint16_t nb_pkts;
-		uint16_t num = (uint16_t)RTE_MIN(nb_receive,
-						 VHOST_MAX_PKT_BURST);
-
-		nb_pkts = rte_vhost_dequeue_burst(r->vid, r->virtqueue_id,
-						  r->mb_pool, &bufs[nb_rx],
-						  num);
-
-		nb_rx += nb_pkts;
-		nb_receive -= nb_pkts;
-		if (nb_pkts < num)
-			break;
+	if (!r->async_register) {
+		while (nb_receive) {
+			num = (uint16_t)RTE_MIN(nb_receive, VHOST_MAX_PKT_BURST);
+			nb_pkts = rte_vhost_dequeue_burst(r->vid, r->virtqueue_id,
+						r->mb_pool, &bufs[nb_rx],
+						num);
+
+			nb_rx += nb_pkts;
+			nb_receive -= nb_pkts;
+			if (nb_pkts < num)
+				break;
+		}
+	} else {
+		int nr_inflight;
+
+		while (nb_receive) {
+			num = (uint16_t)RTE_MIN(nb_receive, VHOST_MAX_PKT_BURST);
+			nb_pkts = rte_vhost_async_try_dequeue_burst(r->vid, r->virtqueue_id,
+						r->mb_pool, &bufs[nb_rx], num, &nr_inflight,
+						r->dma_id, 0);
+
+			nb_rx += nb_pkts;
+			nb_receive -= nb_pkts;
+			if (nb_pkts < num)
+				break;
+		}
 	}
 
 	r->stats.pkts += nb_rx;
@@ -445,6 +528,17 @@  eth_vhost_rx(void *q, struct rte_mbuf **bufs, uint16_t nb_bufs)
 out:
 	rte_atomic32_set(&r->while_queuing, 0);
 
+tx_poll:
+	/**
+	 * Poll and free completed packets for the virtqueue of Tx queue.
+	 * Note that we access Tx queue's virtqueue, which is protected
+	 * by vring lock.
+	 */
+	if (r->txq->async_register && !async_tx_poll_completed &&
+			rte_atomic32_read(&r->txq->allow_queuing) == 1)
+		vhost_tx_free_completed(r->vid, r->txq->virtqueue_id, r->txq->dma_id,
+				r->cmpl_pkts, VHOST_MAX_PKT_BURST);
+
 	return nb_rx;
 }
 
@@ -456,6 +550,7 @@  eth_vhost_tx(void *q, struct rte_mbuf **bufs, uint16_t nb_bufs)
 	uint16_t nb_send = 0;
 	uint64_t nb_bytes = 0;
 	uint64_t nb_missed = 0;
+	uint16_t nb_pkts, num;
 
 	if (unlikely(rte_atomic32_read(&r->allow_queuing) == 0))
 		return 0;
@@ -486,31 +581,49 @@  eth_vhost_tx(void *q, struct rte_mbuf **bufs, uint16_t nb_bufs)
 	}
 
 	/* Enqueue packets to guest RX queue */
-	while (nb_send) {
-		uint16_t nb_pkts;
-		uint16_t num = (uint16_t)RTE_MIN(nb_send,
-						 VHOST_MAX_PKT_BURST);
+	if (!r->async_register) {
+		while (nb_send) {
+			num = (uint16_t)RTE_MIN(nb_send, VHOST_MAX_PKT_BURST);
+			nb_pkts = rte_vhost_enqueue_burst(r->vid, r->virtqueue_id,
+						&bufs[nb_tx], num);
+
+			nb_tx += nb_pkts;
+			nb_send -= nb_pkts;
+			if (nb_pkts < num)
+				break;
+		}
 
-		nb_pkts = rte_vhost_enqueue_burst(r->vid, r->virtqueue_id,
-						  &bufs[nb_tx], num);
+		for (i = 0; likely(i < nb_tx); i++) {
+			nb_bytes += bufs[i]->pkt_len;
+			rte_pktmbuf_free(bufs[i]);
+		}
 
-		nb_tx += nb_pkts;
-		nb_send -= nb_pkts;
-		if (nb_pkts < num)
-			break;
-	}
+	} else {
+		while (nb_send) {
+			num = (uint16_t)RTE_MIN(nb_send, VHOST_MAX_PKT_BURST);
+			nb_pkts = rte_vhost_submit_enqueue_burst(r->vid, r->virtqueue_id,
+							&bufs[nb_tx], num, r->dma_id, 0);
+
+			nb_tx += nb_pkts;
+			nb_send -= nb_pkts;
+			if (nb_pkts < num)
+				break;
+		}
 
-	for (i = 0; likely(i < nb_tx); i++)
-		nb_bytes += bufs[i]->pkt_len;
+		for (i = 0; likely(i < nb_tx); i++)
+			nb_bytes += bufs[i]->pkt_len;
 
-	nb_missed = nb_bufs - nb_tx;
+		if (unlikely(async_tx_poll_completed)) {
+			vhost_tx_free_completed(r->vid, r->virtqueue_id, r->dma_id, r->cmpl_pkts,
+					VHOST_MAX_PKT_BURST);
+		}
+	}
 
+	nb_missed = nb_bufs - nb_tx;
 	r->stats.pkts += nb_tx;
 	r->stats.bytes += nb_bytes;
 	r->stats.missed_pkts += nb_missed;
 
-	for (i = 0; likely(i < nb_tx); i++)
-		rte_pktmbuf_free(bufs[i]);
 out:
 	rte_atomic32_set(&r->while_queuing, 0);
 
@@ -798,6 +911,8 @@  queue_setup(struct rte_eth_dev *eth_dev, struct pmd_internal *internal)
 		vq->vid = internal->vid;
 		vq->internal = internal;
 		vq->port = eth_dev->data->port_id;
+		if (i < eth_dev->data->nb_tx_queues)
+			vq->txq = eth_dev->data->tx_queues[i];
 	}
 	for (i = 0; i < eth_dev->data->nb_tx_queues; i++) {
 		vq = eth_dev->data->tx_queues[i];
@@ -878,6 +993,30 @@  new_device(int vid)
 	return 0;
 }
 
+static inline void
+async_clear_virtqueue(int vid, uint16_t virtqueue_id, int16_t dma_id)
+{
+	struct rte_mbuf *pkts[VHOST_MAX_PKT_BURST];
+	uint16_t i, ret, nr_done = 0;
+
+	if (vid == -1)
+		return;
+
+	while (rte_vhost_async_get_inflight(vid, virtqueue_id) > 0) {
+		ret = rte_vhost_clear_queue(vid, virtqueue_id, pkts, VHOST_MAX_PKT_BURST, dma_id,
+				0);
+		for (i = 0; i < ret ; i++)
+			rte_pktmbuf_free(pkts[i]);
+
+		nr_done += ret;
+	}
+	VHOST_LOG(INFO, "Completed %u pkts for vid-%u vring-%u\n", nr_done, vid, virtqueue_id);
+
+	if (rte_vhost_async_channel_unregister(vid, virtqueue_id))
+		VHOST_LOG(ERR, "Failed to unregister async for vid-%u vring-%u\n", vid,
+				virtqueue_id);
+}
+
 static void
 destroy_device(int vid)
 {
@@ -908,13 +1047,27 @@  destroy_device(int vid)
 			vq = eth_dev->data->rx_queues[i];
 			if (!vq)
 				continue;
+			if (vq->async_register) {
+				async_clear_virtqueue(vq->vid, vq->virtqueue_id,
+							vq->dma_id);
+				vq->async_register = false;
+				internal->queue_dmas[vq->virtqueue_id].async_register = false;
+			}
 			vq->vid = -1;
+
 		}
 		for (i = 0; i < eth_dev->data->nb_tx_queues; i++) {
 			vq = eth_dev->data->tx_queues[i];
 			if (!vq)
 				continue;
+			if (vq->async_register) {
+				async_clear_virtqueue(vq->vid, vq->virtqueue_id,
+							vq->dma_id);
+				vq->async_register = false;
+				internal->queue_dmas[vq->virtqueue_id].async_register = false;
+			}
 			vq->vid = -1;
+
 		}
 	}
 
@@ -983,6 +1136,9 @@  vring_state_changed(int vid, uint16_t vring, int enable)
 	struct rte_vhost_vring_state *state;
 	struct rte_eth_dev *eth_dev;
 	struct internal_list *list;
+	struct vhost_queue *queue;
+	struct pmd_internal *internal;
+	int qid;
 	char ifname[PATH_MAX];
 
 	rte_vhost_get_ifname(vid, ifname, sizeof(ifname));
@@ -1011,6 +1167,65 @@  vring_state_changed(int vid, uint16_t vring, int enable)
 
 	update_queuing_status(eth_dev, false);
 
+	qid = vring / VIRTIO_QNUM;
+	if (vring % VIRTIO_QNUM == VIRTIO_RXQ)
+		queue = eth_dev->data->tx_queues[qid];
+	else
+		queue = eth_dev->data->rx_queues[qid];
+
+	if (!queue)
+		goto skip;
+
+	internal = eth_dev->data->dev_private;
+
+	/* Register async data path for the queue assigned valid DMA device */
+	if (internal->queue_dmas[queue->virtqueue_id].dma_id == INVALID_DMA_ID)
+		goto skip;
+
+	if (enable && !queue->async_register) {
+		if (rte_vhost_async_channel_register_thread_unsafe(vid, vring)) {
+			VHOST_LOG(ERR, "Failed to register async for vid-%u vring-%u!\n", vid,
+					vring);
+			return -1;
+		}
+
+		queue->async_register = true;
+		internal->queue_dmas[vring].async_register = true;
+
+		VHOST_LOG(INFO, "Succeed to register async for vid-%u vring-%u\n", vid, vring);
+	}
+
+	if (!enable && queue->async_register) {
+		struct rte_mbuf *pkts[VHOST_MAX_PKT_BURST];
+		uint16_t ret, i, nr_done = 0;
+		uint16_t dma_id = queue->dma_id;
+
+		while (rte_vhost_async_get_inflight_thread_unsafe(vid, vring) > 0) {
+			ret = rte_vhost_clear_queue_thread_unsafe(vid, vring, pkts,
+					VHOST_MAX_PKT_BURST, dma_id, 0);
+
+			for (i = 0; i < ret ; i++)
+				rte_pktmbuf_free(pkts[i]);
+
+			nr_done += ret;
+		}
+
+		VHOST_LOG(INFO, "Completed %u in-flight pkts for vid-%u vring-%u\n", nr_done, vid,
+				vring);
+
+		if (rte_vhost_async_channel_unregister_thread_unsafe(vid, vring)) {
+			VHOST_LOG(ERR, "Failed to unregister async for vid-%u vring-%u\n", vid,
+					vring);
+			return -1;
+		}
+
+		queue->async_register = false;
+		internal->queue_dmas[vring].async_register = false;
+
+		VHOST_LOG(INFO, "Succeed to unregister async for vid-%u vring-%u\n", vid, vring);
+	}
+
+skip:
 	VHOST_LOG(INFO, "vring%u is %s\n",
 			vring, enable ? "enabled" : "disabled");
 
@@ -1159,6 +1374,12 @@  rte_eth_vhost_get_vid_from_port_id(uint16_t port_id)
 	return vid;
 }
 
+void
+rte_eth_vhost_async_tx_poll_completed(bool enable)
+{
+	async_tx_poll_completed = enable;
+}
+
 static int
 eth_dev_configure(struct rte_eth_dev *dev)
 {
@@ -1220,6 +1441,7 @@  eth_dev_close(struct rte_eth_dev *dev)
 {
 	struct pmd_internal *internal;
 	struct internal_list *list;
+	struct vhost_queue *queue;
 	unsigned int i, ret;
 
 	if (rte_eal_process_type() != RTE_PROC_PRIMARY)
@@ -1233,6 +1455,25 @@  eth_dev_close(struct rte_eth_dev *dev)
 
 	list = find_internal_resource(internal->iface_name);
 	if (list) {
+		/* Make sure all in-flight packets are completed before destroy vhost */
+		if (dev->data->rx_queues) {
+			for (i = 0; i < dev->data->nb_rx_queues; i++) {
+				queue = dev->data->rx_queues[i];
+				if (queue->async_register)
+					async_clear_virtqueue(queue->vid, queue->virtqueue_id,
+							queue->dma_id);
+			}
+		}
+
+		if (dev->data->tx_queues) {
+			for (i = 0; i < dev->data->nb_tx_queues; i++) {
+				queue = dev->data->tx_queues[i];
+				if (queue->async_register)
+					async_clear_virtqueue(queue->vid, queue->virtqueue_id,
+							queue->dma_id);
+			}
+		}
+
 		rte_vhost_driver_unregister(internal->iface_name);
 		pthread_mutex_lock(&internal_list_lock);
 		TAILQ_REMOVE(&internal_list, list, next);
@@ -1267,6 +1508,7 @@  eth_rx_queue_setup(struct rte_eth_dev *dev, uint16_t rx_queue_id,
 		   struct rte_mempool *mb_pool)
 {
 	struct vhost_queue *vq;
+	struct pmd_internal *internal = dev->data->dev_private;
 
 	vq = rte_zmalloc_socket(NULL, sizeof(struct vhost_queue),
 			RTE_CACHE_LINE_SIZE, socket_id);
@@ -1277,6 +1519,8 @@  eth_rx_queue_setup(struct rte_eth_dev *dev, uint16_t rx_queue_id,
 
 	vq->mb_pool = mb_pool;
 	vq->virtqueue_id = rx_queue_id * VIRTIO_QNUM + VIRTIO_TXQ;
+	vq->async_register = internal->queue_dmas[vq->virtqueue_id].async_register;
+	vq->dma_id = internal->queue_dmas[vq->virtqueue_id].dma_id;
 	rte_spinlock_init(&vq->intr_lock);
 	dev->data->rx_queues[rx_queue_id] = vq;
 
@@ -1290,6 +1534,7 @@  eth_tx_queue_setup(struct rte_eth_dev *dev, uint16_t tx_queue_id,
 		   const struct rte_eth_txconf *tx_conf __rte_unused)
 {
 	struct vhost_queue *vq;
+	struct pmd_internal *internal = dev->data->dev_private;
 
 	vq = rte_zmalloc_socket(NULL, sizeof(struct vhost_queue),
 			RTE_CACHE_LINE_SIZE, socket_id);
@@ -1299,6 +1544,8 @@  eth_tx_queue_setup(struct rte_eth_dev *dev, uint16_t tx_queue_id,
 	}
 
 	vq->virtqueue_id = tx_queue_id * VIRTIO_QNUM + VIRTIO_RXQ;
+	vq->async_register = internal->queue_dmas[vq->virtqueue_id].async_register;
+	vq->dma_id = internal->queue_dmas[vq->virtqueue_id].dma_id;
 	rte_spinlock_init(&vq->intr_lock);
 	dev->data->tx_queues[tx_queue_id] = vq;
 
@@ -1509,13 +1756,14 @@  static const struct eth_dev_ops ops = {
 static int
 eth_dev_vhost_create(struct rte_vdev_device *dev, char *iface_name,
 	int16_t queues, const unsigned int numa_node, uint64_t flags,
-	uint64_t disable_flags)
+	uint64_t disable_flags, struct dma_input_info *dma_input)
 {
 	const char *name = rte_vdev_device_name(dev);
 	struct rte_eth_dev_data *data;
 	struct pmd_internal *internal = NULL;
 	struct rte_eth_dev *eth_dev = NULL;
 	struct rte_ether_addr *eth_addr = NULL;
+	int i;
 
 	VHOST_LOG(INFO, "Creating VHOST-USER backend on numa socket %u\n",
 		numa_node);
@@ -1564,6 +1812,12 @@  eth_dev_vhost_create(struct rte_vdev_device *dev, char *iface_name,
 	eth_dev->rx_pkt_burst = eth_vhost_rx;
 	eth_dev->tx_pkt_burst = eth_vhost_tx;
 
+	for (i = 0; i < RTE_MAX_QUEUES_PER_PORT * 2; i++) {
+		/* Invalid DMA ID indicates the queue does not want to enable async data path */
+		internal->queue_dmas[i].dma_id = dma_input->dmas[i];
+		internal->queue_dmas[i].async_register = false;
+	}
+
 	rte_eth_dev_probing_finish(eth_dev);
 	return 0;
 
@@ -1603,6 +1857,155 @@  open_int(const char *key __rte_unused, const char *value, void *extra_args)
 	return 0;
 }
 
+static int
+init_dma(int16_t dma_id, uint16_t ring_size)
+{
+	struct rte_dma_info info;
+	struct rte_dma_conf dev_config = { .nb_vchans = 1 };
+	struct rte_dma_vchan_conf qconf = {
+		.direction = RTE_DMA_DIR_MEM_TO_MEM,
+	};
+	int ret = 0;
+
+	if (dma_is_configured(dma_id))
+		goto out;
+
+	if (rte_dma_info_get(dma_id, &info) != 0) {
+		VHOST_LOG(ERR, "dma %u get info failed\n", dma_id);
+		ret = -1;
+		goto out;
+	}
+
+	if (info.max_vchans < 1) {
+		VHOST_LOG(ERR, "No channels available on dma %d\n", dma_id);
+		ret = -1;
+		goto out;
+	}
+
+	if (rte_dma_configure(dma_id, &dev_config) != 0) {
+		VHOST_LOG(ERR, "dma %u configure failed\n", dma_id);
+		ret = -1;
+		goto out;
+	}
+
+	rte_dma_info_get(dma_id, &info);
+	if (info.nb_vchans != 1) {
+		VHOST_LOG(ERR, "dma %u has no queues\n", dma_id);
+		ret = -1;
+		goto out;
+	}
+
+	ring_size = RTE_MAX(ring_size, MINIMUM_DMA_RING_SIZE);
+	ring_size = RTE_MAX(ring_size, info.min_desc);
+	qconf.nb_desc = RTE_MIN(ring_size, info.max_desc);
+	if (rte_dma_vchan_setup(dma_id, 0, &qconf) != 0) {
+		VHOST_LOG(ERR, "dma %u queue setup failed\n", dma_id);
+		ret = -1;
+		goto out;
+	}
+
+	if (rte_dma_start(dma_id) != 0) {
+		VHOST_LOG(ERR, "dma %u start failed\n", dma_id);
+		ret = -1;
+		goto out;
+	}
+
+	configured_dmas[dma_count++] = dma_id;
+
+out:
+	return ret;
+}
+
+static int
+open_dma(const char *key __rte_unused, const char *value, void *extra_args)
+{
+	struct dma_input_info *dma_input = extra_args;
+	char *input = strndup(value, strlen(value) + 1);
+	char *addrs = input;
+	char *ptrs[2];
+	char *start, *end, *substr;
+	uint16_t qid, virtqueue_id;
+	int16_t dma_id;
+	int i, ret = 0;
+
+	while (isblank(*addrs))
+		addrs++;
+	if (*addrs == '\0') {
+		VHOST_LOG(ERR, "No input DMA addresses\n");
+		ret = -1;
+		goto out;
+	}
+
+	/* process DMA devices within bracket. */
+	addrs++;
+	substr = strtok(addrs, ";]");
+	if (!substr) {
+		VHOST_LOG(ERR, "No input DMA addresse\n");
+		ret = -1;
+		goto out;
+	}
+
+	do {
+		rte_strsplit(substr, strlen(substr), ptrs, 2, '@');
+
+		char *txq, *rxq;
+		bool is_txq;
+
+		txq = strstr(ptrs[0], "txq");
+		rxq = strstr(ptrs[0], "rxq");
+		if (txq == NULL && rxq == NULL) {
+			VHOST_LOG(ERR, "Illegal queue\n");
+			ret = -1;
+			goto out;
+		} else if (txq) {
+			is_txq = true;
+			start = txq;
+		} else {
+			is_txq = false;
+			start = rxq;
+		}
+
+		start += 3;
+		qid = strtol(start, &end, 0);
+		if (end == start) {
+			VHOST_LOG(ERR, "No input queue ID\n");
+			ret = -1;
+			goto out;
+		}
+
+		virtqueue_id = is_txq ? qid * 2 + VIRTIO_RXQ : qid * 2 + VIRTIO_TXQ;
+
+		dma_id = rte_dma_get_dev_id_by_name(ptrs[1]);
+		if (dma_id < 0) {
+			VHOST_LOG(ERR, "Fail to find DMA device %s.\n", ptrs[1]);
+			ret = -1;
+			goto out;
+		}
+
+		ret = init_dma(dma_id, dma_input->dma_ring_size);
+		if (ret != 0) {
+			VHOST_LOG(ERR, "Fail to initialize DMA %u\n", dma_id);
+			ret = -1;
+			break;
+		}
+
+		dma_input->dmas[virtqueue_id] = dma_id;
+
+		substr = strtok(NULL, ";]");
+	} while (substr);
+
+	for (i = 0; i < dma_count; i++) {
+		if (rte_vhost_async_dma_configure(configured_dmas[i], 0) < 0) {
+			VHOST_LOG(ERR, "Fail to configure DMA %u to vhost\n", configured_dmas[i]);
+			ret = -1;
+		}
+	}
+
+out:
+	free(input);
+	return ret;
+}
+
 static int
 rte_pmd_vhost_probe(struct rte_vdev_device *dev)
 {
@@ -1621,6 +2024,10 @@  rte_pmd_vhost_probe(struct rte_vdev_device *dev)
 	int legacy_ol_flags = 0;
 	struct rte_eth_dev *eth_dev;
 	const char *name = rte_vdev_device_name(dev);
+	struct dma_input_info dma_input;
+
+	memset(dma_input.dmas, INVALID_DMA_ID, sizeof(dma_input.dmas));
+	dma_input.dma_ring_size = DEFAULT_DMA_RING_SIZE;
 
 	VHOST_LOG(INFO, "Initializing pmd_vhost for %s\n", name);
 
@@ -1736,6 +2143,43 @@  rte_pmd_vhost_probe(struct rte_vdev_device *dev)
 			goto out_free;
 	}
 
+	if (rte_kvargs_count(kvlist, ETH_VHOST_DMA_RING_SIZE) == 1) {
+		if (rte_kvargs_count(kvlist, ETH_VHOST_DMA_ARG) == 1) {
+			ret = rte_kvargs_process(kvlist, ETH_VHOST_DMA_RING_SIZE,
+					&open_int, &dma_input.dma_ring_size);
+			if (ret < 0)
+				goto out_free;
+
+			if (!rte_is_power_of_2(dma_input.dma_ring_size)) {
+				dma_input.dma_ring_size = rte_align32pow2(dma_input.dma_ring_size);
+				VHOST_LOG(INFO, "Convert dma_ring_size to the power of two %u\n",
+						dma_input.dma_ring_size);
+			}
+		} else {
+			VHOST_LOG(WARNING, "%s is not specified, skip to parse %s\n",
+					ETH_VHOST_DMA_ARG, ETH_VHOST_DMA_RING_SIZE);
+		}
+	}
+
+	if (rte_kvargs_count(kvlist, ETH_VHOST_DMA_ARG) == 1) {
+		if (rte_kvargs_count(kvlist, ETH_VHOST_DMA_RING_SIZE) == 0)
+			VHOST_LOG(INFO, "Use default dma ring size %d\n", DEFAULT_DMA_RING_SIZE);
+
+		ret = rte_kvargs_process(kvlist, ETH_VHOST_DMA_ARG,
+					 &open_dma, &dma_input);
+		if (ret < 0) {
+			VHOST_LOG(ERR, "Failed to parse %s\n", ETH_VHOST_DMA_ARG);
+			goto out_free;
+		}
+
+		flags |= RTE_VHOST_USER_ASYNC_COPY;
+		/**
+		 * Don't support live migration when enable
+		 * DMA acceleration.
+		 */
+		disable_flags |= (1ULL << VHOST_F_LOG_ALL);
+	}
+
 	if (legacy_ol_flags == 0)
 		flags |= RTE_VHOST_USER_NET_COMPLIANT_OL_FLAGS;
 
@@ -1743,7 +2187,7 @@  rte_pmd_vhost_probe(struct rte_vdev_device *dev)
 		dev->device.numa_node = rte_socket_id();
 
 	ret = eth_dev_vhost_create(dev, iface_name, queues,
-				   dev->device.numa_node, flags, disable_flags);
+			dev->device.numa_node, flags, disable_flags, &dma_input);
 	if (ret == -1)
 		VHOST_LOG(ERR, "Failed to create %s\n", name);
 
@@ -1787,4 +2231,6 @@  RTE_PMD_REGISTER_PARAM_STRING(net_vhost,
 	"postcopy-support=<0|1> "
 	"tso=<0|1> "
 	"linear-buffer=<0|1> "
-	"ext-buffer=<0|1>");
+	"ext-buffer=<0|1> "
+	"dma-ring-size=<int> "
+	"dmas=[txq0@dma_addr;rxq0@dma_addr]");
diff --git a/drivers/net/vhost/rte_eth_vhost.h b/drivers/net/vhost/rte_eth_vhost.h
index 0e68b9f668..146c98803d 100644
--- a/drivers/net/vhost/rte_eth_vhost.h
+++ b/drivers/net/vhost/rte_eth_vhost.h
@@ -52,6 +52,21 @@  int rte_eth_vhost_get_queue_event(uint16_t port_id,
  */
 int rte_eth_vhost_get_vid_from_port_id(uint16_t port_id);
 
+/**
+ * @warning
+ * @b EXPERIMENTAL: this API may change, or be removed, without prior notice
+ *
+ * By default, rte_vhost_poll_enqueue_completed() is called in Rx path.
+ * This function enables Tx path, rather than Rx path, to poll completed
+ * packets for vhost async enqueue operations. Note that virtio may never
+ * receive DMA completed packets if there are no more Tx operations.
+ *
+ * @param enable
+ *  True indicates Tx path to call rte_vhost_poll_enqueue_completed().
+ */
+__rte_experimental
+void rte_eth_vhost_async_tx_poll_completed(bool enable);
+
 #ifdef __cplusplus
 }
 #endif
diff --git a/drivers/net/vhost/version.map b/drivers/net/vhost/version.map
index e42c89f1eb..0a40441227 100644
--- a/drivers/net/vhost/version.map
+++ b/drivers/net/vhost/version.map
@@ -6,3 +6,10 @@  DPDK_23 {
 
 	local: *;
 };
+
+EXPERIMENTAL {
+	global:
+
+	# added in 22.11
+	rte_eth_vhost_async_tx_poll_completed;
+};
diff --git a/drivers/net/vhost/vhost_testpmd.c b/drivers/net/vhost/vhost_testpmd.c
new file mode 100644
index 0000000000..11990ea152
--- /dev/null
+++ b/drivers/net/vhost/vhost_testpmd.c
@@ -0,0 +1,67 @@ 
+/* SPDX-License-Identifier: BSD-3-Clause
+ * Copyright(c) 2022 Intel Corporation.
+ */
+#include <rte_eth_vhost.h>
+#include <cmdline_parse_num.h>
+#include <cmdline_parse_string.h>
+
+#include "testpmd.h"
+
+struct cmd_tx_poll_result {
+	cmdline_fixed_string_t async_vhost;
+	cmdline_fixed_string_t tx;
+	cmdline_fixed_string_t poll;
+	cmdline_fixed_string_t completed;
+	cmdline_fixed_string_t what;
+};
+
+static cmdline_parse_token_string_t cmd_tx_async_vhost =
+	TOKEN_STRING_INITIALIZER(struct cmd_tx_poll_result, async_vhost, "async_vhost");
+static cmdline_parse_token_string_t cmd_tx_tx =
+	TOKEN_STRING_INITIALIZER(struct cmd_tx_poll_result, tx, "tx");
+static cmdline_parse_token_string_t cmd_tx_poll =
+	TOKEN_STRING_INITIALIZER(struct cmd_tx_poll_result, poll, "poll");
+static cmdline_parse_token_string_t cmd_tx_completed =
+	TOKEN_STRING_INITIALIZER(struct cmd_tx_poll_result, completed, "completed");
+static cmdline_parse_token_string_t cmd_tx_what =
+	TOKEN_STRING_INITIALIZER(struct cmd_tx_poll_result, what, "on#off");
+
+static void
+cmd_tx_poll_parsed(void *parsed_result, __rte_unused struct cmdline *cl, __rte_unused void *data)
+{
+	struct cmd_tx_poll_result *res = parsed_result;
+
+	if (!strcmp(res->what, "on"))
+		rte_eth_vhost_async_tx_poll_completed(true);
+	else if (!strcmp(res->what, "off"))
+		rte_eth_vhost_async_tx_poll_completed(false);
+	else
+		fprintf(stderr, "Unknown parameter\n");
+}
+
+static cmdline_parse_inst_t async_vhost_cmd_tx_poll = {
+	.f = cmd_tx_poll_parsed,
+	.data = NULL,
+	.help_str = "async-vhost tx poll completed on|off",
+	.tokens = {
+		(void *)&cmd_tx_async_vhost,
+		(void *)&cmd_tx_tx,
+		(void *)&cmd_tx_poll,
+		(void *)&cmd_tx_completed,
+		(void *)&cmd_tx_what,
+		NULL,
+	},
+};
+
+static struct testpmd_driver_commands async_vhost_cmds = {
+	.commands = {
+	{
+		&async_vhost_cmd_tx_poll,
+		"async_vhost tx poll completed (on|off)\n"
+		"    Poll and free DMA completed packets in Tx path.\n",
+	},
+	{ NULL, NULL },
+	},
+};
+
+TESTPMD_ADD_DRIVER_COMMANDS(async_vhost_cmds)