On Wed, Oct 15, 2014 at 03:25:30PM +0800, Jason Wang wrote:
> 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 <ru...@rustcorp.com.au>
> Cc: Michael S. Tsirkin <m...@redhat.com>
> Signed-off-by: Jason Wang <jasow...@redhat.com>
I think you should split xmit_more stuff out.
> ---
> 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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