[v2,3/4] net/virtio: allocate fake mbuf in Rx queue
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Commit Message
While it is worth clarifying whether the fake mbuf
in virtnet_rx struct is really necessary, it is sure
that it heavily impacts cache usage by being part of
the struct. Indeed, it uses two cachelines, and
requires alignement on a cacheline.
Before this series, it means it took 120 bytes in
virtnet_rx struct:
struct virtnet_rx {
struct virtqueue * vq; /* 0 8 */
/* XXX 56 bytes hole, try to pack */
/* --- cacheline 1 boundary (64 bytes) --- */
struct rte_mbuf fake_mbuf __attribute__((__aligned__(64))); /* 64 128 */
/* --- cacheline 3 boundary (192 bytes) --- */
This patch allocates it using malloc in order to optimize
virtnet_rx cache usage and so virtqueue cache usage.
Signed-off-by: Maxime Coquelin <maxime.coquelin@redhat.com>
---
drivers/net/virtio/virtio_ethdev.c | 13 +++++++++++++
drivers/net/virtio/virtio_rxtx.c | 8 +++-----
drivers/net/virtio/virtio_rxtx.h | 2 +-
3 files changed, 17 insertions(+), 6 deletions(-)
Comments
On Mon, Mar 15, 2021 at 4:20 PM Maxime Coquelin
<maxime.coquelin@redhat.com> wrote:
> @@ -550,10 +551,18 @@ virtio_init_queue(struct rte_eth_dev *dev, uint16_t queue_idx)
> goto free_hdr_mz;
> }
>
> + fake_mbuf = malloc(sizeof(*fake_mbuf));
> + if (!fake_mbuf) {
> + PMD_INIT_LOG(ERR, "can not allocate fake mbuf");
> + ret = -ENOMEM;
> + goto free_sw_ring;
> + }
> +
> vq->sw_ring = sw_ring;
> rxvq = &vq->rxq;
> rxvq->port_id = dev->data->port_id;
> rxvq->mz = mz;
> + rxvq->fake_mbuf = fake_mbuf;
IIRC, vq is allocated as dpdk memory (rte_malloc).
Generally speaking, storing a local pointer inside such an object is
dangerous if other processes start to look at this part.
> } else if (queue_type == VTNET_TQ) {
> txvq = &vq->txq;
> txvq->port_id = dev->data->port_id;
> @@ -613,6 +622,9 @@ virtio_init_queue(struct rte_eth_dev *dev, uint16_t queue_idx)
> clean_vq:
> hw->cvq = NULL;
>
> + if (fake_mbuf)
> + free(fake_mbuf);
No need for if().
On 3/15/21 4:50 PM, David Marchand wrote:
> On Mon, Mar 15, 2021 at 4:20 PM Maxime Coquelin
> <maxime.coquelin@redhat.com> wrote:
>> @@ -550,10 +551,18 @@ virtio_init_queue(struct rte_eth_dev *dev, uint16_t queue_idx)
>> goto free_hdr_mz;
>> }
>>
>> + fake_mbuf = malloc(sizeof(*fake_mbuf));
>> + if (!fake_mbuf) {
>> + PMD_INIT_LOG(ERR, "can not allocate fake mbuf");
>> + ret = -ENOMEM;
>> + goto free_sw_ring;
>> + }
>> +
>> vq->sw_ring = sw_ring;
>> rxvq = &vq->rxq;
>> rxvq->port_id = dev->data->port_id;
>> rxvq->mz = mz;
>> + rxvq->fake_mbuf = fake_mbuf;
>
> IIRC, vq is allocated as dpdk memory (rte_malloc).
> Generally speaking, storing a local pointer inside such an object is
> dangerous if other processes start to look at this part.
Agree, I will change to rte_zmalloc_socket, as vq (which is was part of)
is allocated like that.
Thanks,
Maxime
>
>> } else if (queue_type == VTNET_TQ) {
>> txvq = &vq->txq;
>> txvq->port_id = dev->data->port_id;
>> @@ -613,6 +622,9 @@ virtio_init_queue(struct rte_eth_dev *dev, uint16_t queue_idx)
>> clean_vq:
>> hw->cvq = NULL;
>>
>> + if (fake_mbuf)
>> + free(fake_mbuf);
>
> No need for if().
>
>
@@ -435,6 +435,7 @@ virtio_init_queue(struct rte_eth_dev *dev, uint16_t queue_idx)
int queue_type = virtio_get_queue_type(hw, queue_idx);
int ret;
int numa_node = dev->device->numa_node;
+ struct rte_mbuf *fake_mbuf = NULL;
PMD_INIT_LOG(INFO, "setting up queue: %u on NUMA node %d",
queue_idx, numa_node);
@@ -550,10 +551,18 @@ virtio_init_queue(struct rte_eth_dev *dev, uint16_t queue_idx)
goto free_hdr_mz;
}
+ fake_mbuf = malloc(sizeof(*fake_mbuf));
+ if (!fake_mbuf) {
+ PMD_INIT_LOG(ERR, "can not allocate fake mbuf");
+ ret = -ENOMEM;
+ goto free_sw_ring;
+ }
+
vq->sw_ring = sw_ring;
rxvq = &vq->rxq;
rxvq->port_id = dev->data->port_id;
rxvq->mz = mz;
+ rxvq->fake_mbuf = fake_mbuf;
} else if (queue_type == VTNET_TQ) {
txvq = &vq->txq;
txvq->port_id = dev->data->port_id;
@@ -613,6 +622,9 @@ virtio_init_queue(struct rte_eth_dev *dev, uint16_t queue_idx)
clean_vq:
hw->cvq = NULL;
+ if (fake_mbuf)
+ free(fake_mbuf);
+free_sw_ring:
if (sw_ring)
rte_free(sw_ring);
free_hdr_mz:
@@ -643,6 +655,7 @@ virtio_free_queues(struct virtio_hw *hw)
queue_type = virtio_get_queue_type(hw, i);
if (queue_type == VTNET_RQ) {
+ free(vq->rxq.fake_mbuf);
rte_free(vq->sw_ring);
rte_memzone_free(vq->rxq.mz);
} else if (queue_type == VTNET_TQ) {
@@ -703,11 +703,9 @@ virtio_dev_rx_queue_setup_finish(struct rte_eth_dev *dev, uint16_t queue_idx)
virtio_rxq_vec_setup(rxvq);
}
- memset(&rxvq->fake_mbuf, 0, sizeof(rxvq->fake_mbuf));
- for (desc_idx = 0; desc_idx < RTE_PMD_VIRTIO_RX_MAX_BURST;
- desc_idx++) {
- vq->sw_ring[vq->vq_nentries + desc_idx] =
- &rxvq->fake_mbuf;
+ memset(rxvq->fake_mbuf, 0, sizeof(*rxvq->fake_mbuf));
+ for (desc_idx = 0; desc_idx < RTE_PMD_VIRTIO_RX_MAX_BURST; desc_idx++) {
+ vq->sw_ring[vq->vq_nentries + desc_idx] = rxvq->fake_mbuf;
}
if (hw->use_vec_rx && !virtio_with_packed_queue(hw)) {
@@ -19,7 +19,7 @@ struct virtnet_stats {
struct virtnet_rx {
/* dummy mbuf, for wraparound when processing RX ring. */
- struct rte_mbuf fake_mbuf;
+ struct rte_mbuf *fake_mbuf;
uint64_t mbuf_initializer; /**< value to init mbufs. */
struct rte_mempool *mpool; /**< mempool for mbuf allocation */