vhost: allow to check in-flight packets for async vhost

  This patch allows to check the amount of in-flight packets
for vhost queues which register async channel acceleration.

Signed-off-by: Jiayu Hu <jiayu.hu@intel.com>
---
 doc/guides/prog_guide/vhost_lib.rst |  5 +++++
 lib/vhost/rte_vhost_async.h         | 14 ++++++++++++++
 lib/vhost/version.map               |  3 +++
 lib/vhost/vhost.c                   | 35 +++++++++++++++++++++++++++++++++++
 4 files changed, 57 insertions(+)
  

Hi Jiayu,

On 6/2/21 5:05 PM, Jiayu Hu wrote:
> This patch allows to check the amount of in-flight packets
> for vhost queues which register async channel acceleration.
> 
> Signed-off-by: Jiayu Hu <jiayu.hu@intel.com>
> ---
>  doc/guides/prog_guide/vhost_lib.rst |  5 +++++
>  lib/vhost/rte_vhost_async.h         | 14 ++++++++++++++
>  lib/vhost/version.map               |  3 +++
>  lib/vhost/vhost.c                   | 35 +++++++++++++++++++++++++++++++++++
>  4 files changed, 57 insertions(+)
> 
> diff --git a/doc/guides/prog_guide/vhost_lib.rst b/doc/guides/prog_guide/vhost_lib.rst
> index d18fb98..9fdc6d5 100644
> --- a/doc/guides/prog_guide/vhost_lib.rst
> +++ b/doc/guides/prog_guide/vhost_lib.rst
> @@ -281,6 +281,11 @@ The following is an overview of some key Vhost API functions:
>    Poll enqueue completion status from async data path. Completed packets
>    are returned to applications through ``pkts``.
>  
> +* ``rte_vhost_async_get_inflight(vid, queue_id)``
> +
> +  This function returns the amount of in-flight packets by now for the
> +  vhost queue which registers async channel acceleration.
> +
>  Vhost-user Implementations
>  --------------------------
>  
> diff --git a/lib/vhost/rte_vhost_async.h b/lib/vhost/rte_vhost_async.h
> index 6faa31f..553da4d 100644
> --- a/lib/vhost/rte_vhost_async.h
> +++ b/lib/vhost/rte_vhost_async.h
> @@ -193,4 +193,18 @@ __rte_experimental
>  uint16_t rte_vhost_poll_enqueue_completed(int vid, uint16_t queue_id,
>  		struct rte_mbuf **pkts, uint16_t count);
>  
> +/**
> + * This function returns the amount of in-flight packets by now
> + * for the vhost queue which registers async channel acceleration.
> + *
> + * @param vid
> + *  id of vhost device to enqueue data
> + * @param queue_id
> + *  queue id to enqueue data
> + * @return
> + *  the amount of in-flight packets on success; -1 on failure
> + */
> +__rte_experimental
> +int rte_vhost_async_get_inflight(int vid, uint16_t queue_id);
> +
>  #endif /* _RTE_VHOST_ASYNC_H_ */
> diff --git a/lib/vhost/version.map b/lib/vhost/version.map
> index 9103a23..28238cb 100644
> --- a/lib/vhost/version.map
> +++ b/lib/vhost/version.map
> @@ -79,4 +79,7 @@ EXPERIMENTAL {
>  
>  	# added in 21.05
>  	rte_vhost_get_negotiated_protocol_features;
> +
> +	# added in 21.08
> +	rte_vhost_async_get_inflight;
>  };
> diff --git a/lib/vhost/vhost.c b/lib/vhost/vhost.c
> index c96f633..4547705 100644
> --- a/lib/vhost/vhost.c
> +++ b/lib/vhost/vhost.c
> @@ -1780,5 +1780,40 @@ int rte_vhost_async_channel_unregister(int vid, uint16_t queue_id)
>  	return ret;
>  }
>  
> +int rte_vhost_async_get_inflight(int vid, uint16_t queue_id)
> +{
> +	struct vhost_virtqueue *vq;
> +	struct virtio_net *dev = get_device(vid);
> +	int ret = -1;
> +
> +	if (dev == NULL)
> +		return ret;
> +
> +	if (queue_id >= VHOST_MAX_VRING)
> +		return ret;
> +
> +	vq = dev->virtqueue[queue_id];
> +
> +	if (vq == NULL)
> +		return ret;
> +
> +	ret = 0;
> +
> +	if (!vq->async_registered)
> +		return ret;
> +
> +	if (!rte_spinlock_trylock(&vq->access_lock)) {
> +		VHOST_LOG_CONFIG(ERR, "Failed to check in-flight packets. "
> +			"virt queue busy.\n");

Maybe better to use DEBUG log level here, as it could flood the logs.

> +		return -1;
> +	}
> +
> +	ret = vq->async_pkts_inflight_n;
> +	rte_spinlock_unlock(&vq->access_lock);
> +
> +	return ret;
> +
> +}
> +
>  RTE_LOG_REGISTER_SUFFIX(vhost_config_log_level, config, INFO);
>  RTE_LOG_REGISTER_SUFFIX(vhost_data_log_level, data, WARNING);
>