diff mbox series

[net,stable,v1,2/3] virtio_net: separate the logic of checking whether sq is full

Message ID 20230308024935.91686-3-xuanzhuo@linux.alibaba.com (mailing list archive)
State Accepted
Commit b8ef4809bc7faa22e63de921ef56de21ed191af0
Delegated to: Netdev Maintainers
Headers show
Series add checking sq is full inside xdp xmit | expand

Checks

Context Check Description
netdev/series_format success Posting correctly formatted
netdev/tree_selection success Clearly marked for net
netdev/fixes_present success Fixes tag present in non-next series
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 20 this patch: 20
netdev/cc_maintainers success CCed 9 of 9 maintainers
netdev/build_clang success Errors and warnings before: 18 this patch: 18
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/deprecated_api success None detected
netdev/check_selftest success No net selftest shell script
netdev/verify_fixes success No Fixes tag
netdev/build_allmodconfig_warn success Errors and warnings before: 20 this patch: 20
netdev/checkpatch warning CHECK: spaces preferred around that '+' (ctx:VxV)
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/source_inline success Was 0 now: 0

Commit Message

Xuan Zhuo March 8, 2023, 2:49 a.m. UTC 
Separate the logic of checking whether sq is full. The subsequent patch
will reuse this func.

Signed-off-by: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
Reviewed-by: Alexander Duyck <alexanderduyck@fb.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
---
 drivers/net/virtio_net.c | 60 ++++++++++++++++++++++++----------------
 1 file changed, 36 insertions(+), 24 deletions(-)

Comments

Jason Wang March 8, 2023, 5:20 a.m. UTC | #1 
On Wed, Mar 8, 2023 at 10:49 AM Xuan Zhuo <xuanzhuo@linux.alibaba.com> wrote:
>
> Separate the logic of checking whether sq is full. The subsequent patch
> will reuse this func.
>
> Signed-off-by: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
> Reviewed-by: Alexander Duyck <alexanderduyck@fb.com>
> Acked-by: Michael S. Tsirkin <mst@redhat.com>

Acked-by: Jason Wang <jasowang@redhat.com>

Thanks

> ---
>  drivers/net/virtio_net.c | 60 ++++++++++++++++++++++++----------------
>  1 file changed, 36 insertions(+), 24 deletions(-)
>
> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> index 8b31a04052f2..46bbddaadb0d 100644
> --- a/drivers/net/virtio_net.c
> +++ b/drivers/net/virtio_net.c
> @@ -591,6 +591,41 @@ static bool is_xdp_raw_buffer_queue(struct virtnet_info *vi, int q)
>                 return false;
>  }
>
> +static void check_sq_full_and_disable(struct virtnet_info *vi,
> +                                     struct net_device *dev,
> +                                     struct send_queue *sq)
> +{
> +       bool use_napi = sq->napi.weight;
> +       int qnum;
> +
> +       qnum = sq - vi->sq;
> +
> +       /* If running out of space, stop queue to avoid getting packets that we
> +        * are then unable to transmit.
> +        * An alternative would be to force queuing layer to requeue the skb by
> +        * returning NETDEV_TX_BUSY. However, NETDEV_TX_BUSY should not be
> +        * returned in a normal path of operation: it means that driver is not
> +        * maintaining the TX queue stop/start state properly, and causes
> +        * the stack to do a non-trivial amount of useless work.
> +        * Since most packets only take 1 or 2 ring slots, stopping the queue
> +        * early means 16 slots are typically wasted.
> +        */
> +       if (sq->vq->num_free < 2+MAX_SKB_FRAGS) {
> +               netif_stop_subqueue(dev, qnum);
> +               if (use_napi) {
> +                       if (unlikely(!virtqueue_enable_cb_delayed(sq->vq)))
> +                               virtqueue_napi_schedule(&sq->napi, sq->vq);
> +               } else if (unlikely(!virtqueue_enable_cb_delayed(sq->vq))) {
> +                       /* More just got used, free them then recheck. */
> +                       free_old_xmit_skbs(sq, false);
> +                       if (sq->vq->num_free >= 2+MAX_SKB_FRAGS) {
> +                               netif_start_subqueue(dev, qnum);
> +                               virtqueue_disable_cb(sq->vq);
> +                       }
> +               }
> +       }
> +}
> +
>  static int __virtnet_xdp_xmit_one(struct virtnet_info *vi,
>                                    struct send_queue *sq,
>                                    struct xdp_frame *xdpf)
> @@ -1989,30 +2024,7 @@ static netdev_tx_t start_xmit(struct sk_buff *skb, struct net_device *dev)
>                 nf_reset_ct(skb);
>         }
>
> -       /* If running out of space, stop queue to avoid getting packets that we
> -        * are then unable to transmit.
> -        * An alternative would be to force queuing layer to requeue the skb by
> -        * returning NETDEV_TX_BUSY. However, NETDEV_TX_BUSY should not be
> -        * returned in a normal path of operation: it means that driver is not
> -        * maintaining the TX queue stop/start state properly, and causes
> -        * the stack to do a non-trivial amount of useless work.
> -        * Since most packets only take 1 or 2 ring slots, stopping the queue
> -        * early means 16 slots are typically wasted.
> -        */
> -       if (sq->vq->num_free < 2+MAX_SKB_FRAGS) {
> -               netif_stop_subqueue(dev, qnum);
> -               if (use_napi) {
> -                       if (unlikely(!virtqueue_enable_cb_delayed(sq->vq)))
> -                               virtqueue_napi_schedule(&sq->napi, sq->vq);
> -               } else if (unlikely(!virtqueue_enable_cb_delayed(sq->vq))) {
> -                       /* More just got used, free them then recheck. */
> -                       free_old_xmit_skbs(sq, false);
> -                       if (sq->vq->num_free >= 2+MAX_SKB_FRAGS) {
> -                               netif_start_subqueue(dev, qnum);
> -                               virtqueue_disable_cb(sq->vq);
> -                       }
> -               }
> -       }
> +       check_sq_full_and_disable(vi, dev, sq);
>
>         if (kick || netif_xmit_stopped(txq)) {
>                 if (virtqueue_kick_prepare(sq->vq) && virtqueue_notify(sq->vq)) {
> --
> 2.32.0.3.g01195cf9f
>
diff mbox series

Patch

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 8b31a04052f2..46bbddaadb0d 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -591,6 +591,41 @@  static bool is_xdp_raw_buffer_queue(struct virtnet_info *vi, int q)
 		return false;
 }
 
+static void check_sq_full_and_disable(struct virtnet_info *vi,
+				      struct net_device *dev,
+				      struct send_queue *sq)
+{
+	bool use_napi = sq->napi.weight;
+	int qnum;
+
+	qnum = sq - vi->sq;
+
+	/* If running out of space, stop queue to avoid getting packets that we
+	 * are then unable to transmit.
+	 * An alternative would be to force queuing layer to requeue the skb by
+	 * returning NETDEV_TX_BUSY. However, NETDEV_TX_BUSY should not be
+	 * returned in a normal path of operation: it means that driver is not
+	 * maintaining the TX queue stop/start state properly, and causes
+	 * the stack to do a non-trivial amount of useless work.
+	 * Since most packets only take 1 or 2 ring slots, stopping the queue
+	 * early means 16 slots are typically wasted.
+	 */
+	if (sq->vq->num_free < 2+MAX_SKB_FRAGS) {
+		netif_stop_subqueue(dev, qnum);
+		if (use_napi) {
+			if (unlikely(!virtqueue_enable_cb_delayed(sq->vq)))
+				virtqueue_napi_schedule(&sq->napi, sq->vq);
+		} else if (unlikely(!virtqueue_enable_cb_delayed(sq->vq))) {
+			/* More just got used, free them then recheck. */
+			free_old_xmit_skbs(sq, false);
+			if (sq->vq->num_free >= 2+MAX_SKB_FRAGS) {
+				netif_start_subqueue(dev, qnum);
+				virtqueue_disable_cb(sq->vq);
+			}
+		}
+	}
+}
+
 static int __virtnet_xdp_xmit_one(struct virtnet_info *vi,
 				   struct send_queue *sq,
 				   struct xdp_frame *xdpf)
@@ -1989,30 +2024,7 @@  static netdev_tx_t start_xmit(struct sk_buff *skb, struct net_device *dev)
 		nf_reset_ct(skb);
 	}
 
-	/* If running out of space, stop queue to avoid getting packets that we
-	 * are then unable to transmit.
-	 * An alternative would be to force queuing layer to requeue the skb by
-	 * returning NETDEV_TX_BUSY. However, NETDEV_TX_BUSY should not be
-	 * returned in a normal path of operation: it means that driver is not
-	 * maintaining the TX queue stop/start state properly, and causes
-	 * the stack to do a non-trivial amount of useless work.
-	 * Since most packets only take 1 or 2 ring slots, stopping the queue
-	 * early means 16 slots are typically wasted.
-	 */
-	if (sq->vq->num_free < 2+MAX_SKB_FRAGS) {
-		netif_stop_subqueue(dev, qnum);
-		if (use_napi) {
-			if (unlikely(!virtqueue_enable_cb_delayed(sq->vq)))
-				virtqueue_napi_schedule(&sq->napi, sq->vq);
-		} else if (unlikely(!virtqueue_enable_cb_delayed(sq->vq))) {
-			/* More just got used, free them then recheck. */
-			free_old_xmit_skbs(sq, false);
-			if (sq->vq->num_free >= 2+MAX_SKB_FRAGS) {
-				netif_start_subqueue(dev, qnum);
-				virtqueue_disable_cb(sq->vq);
-			}
-		}
-	}
+	check_sq_full_and_disable(vi, dev, sq);
 
 	if (kick || netif_xmit_stopped(txq)) {
 		if (virtqueue_kick_prepare(sq->vq) && virtqueue_notify(sq->vq)) {