With the help of xmit_more and virtqueue_enable_cb_avail(), this patch
enable tx interrupt only for the final skb in the chain if
needed. This will help to mitigate tx interrupts.
Cc: Rusty Russell <rusty@xxxxxxxxxxxxxxx>
Cc: Michael S. Tsirkin <mst@xxxxxxxxxx>
Signed-off-by: Jason Wang <jasowang@xxxxxxxxxx>
---
drivers/net/virtio_net.c | 10 +++++++---
1 files changed, 7 insertions(+), 3 deletions(-)
diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 2afc2e2..5943f3f 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -993,12 +993,16 @@ static netdev_tx_t start_xmit(struct sk_buff *skb, struct net_device *dev)
virtqueue_disable_cb(sq->vq);
}
}
- } else if (virtqueue_enable_cb(sq->vq)) {
- free_old_xmit_skbs(sq, qsize);
}
- if (__netif_subqueue_stopped(dev, qnum) || !skb->xmit_more)
+ if (__netif_subqueue_stopped(dev, qnum) || !skb->xmit_more) {
virtqueue_kick(sq->vq);
+ if (sq->vq->num_free >= 2 +MAX_SKB_FRAGS &&
+ unlikely(virtqueue_enable_cb_avail(sq->vq))) {
+ free_old_xmit_skbs(sq, qsize);
+ virtqueue_disable_cb(sq->vq);
+ }
+ }
return NETDEV_TX_OK;
}
--
1.7.1
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