linux-kernel - Re: [PATCH v2] virtio_net: simplify tx queue wake condition check

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Message-ID: <CAPpAL=wvL2LfRV5BFgLVG69hUoO5fYVx6WEK-PimjoQpy1S7ZA@mail.gmail.com>
Date: Tue, 15 Jul 2025 23:31:35 +0800
From: Lei Yang <leiyang@...hat.com>
To: liming.wu@...uarmicro.com
Cc: "Michael S . Tsirkin" <mst@...hat.com>, Jason Wang <jasowang@...hat.com>, 
	Jakub Kicinski <kuba@...nel.org>, kvm@...r.kernel.org, 
	virtualization@...ts.linux-foundation.org, netdev@...r.kernel.org, 
	linux-kernel@...r.kernel.org, angus.chen@...uarmicro.com
Subject: Re: [PATCH v2] virtio_net: simplify tx queue wake condition check

Tested this series of patches v2 with virtio-net regression tests,
everything works fine.

Tested-by: Lei Yang <leiyang@...hat.com>

On Thu, Jul 10, 2025 at 10:32 AM <liming.wu@...uarmicro.com> wrote:
>
> From: Liming Wu <liming.wu@...uarmicro.com>
>
> Consolidate the two nested if conditions for checking tx queue wake
> conditions into a single combined condition. This improves code
> readability without changing functionality. And move netif_tx_wake_queue
> into if condition to reduce unnecessary checks for queue stops.
>
> Signed-off-by: Liming Wu <liming.wu@...uarmicro.com>
> Tested-by: Lei Yang <leiyang@...hat.com>
> Acked-by: Jason Wang <jasowang@...hat.com>
> ---
>  drivers/net/virtio_net.c | 22 ++++++++++------------
>  1 file changed, 10 insertions(+), 12 deletions(-)
>
> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> index 5d674eb9a0f2..07a378220643 100644
> --- a/drivers/net/virtio_net.c
> +++ b/drivers/net/virtio_net.c
> @@ -3021,12 +3021,11 @@ static void virtnet_poll_cleantx(struct receive_queue *rq, int budget)
>                         free_old_xmit(sq, txq, !!budget);
>                 } while (unlikely(!virtqueue_enable_cb_delayed(sq->vq)));
>
> -               if (sq->vq->num_free >= MAX_SKB_FRAGS + 2) {
> -                       if (netif_tx_queue_stopped(txq)) {
> -                               u64_stats_update_begin(&sq->stats.syncp);
> -                               u64_stats_inc(&sq->stats.wake);
> -                               u64_stats_update_end(&sq->stats.syncp);
> -                       }
> +               if (sq->vq->num_free >= MAX_SKB_FRAGS + 2 &&
> +                   netif_tx_queue_stopped(txq)) {
> +                       u64_stats_update_begin(&sq->stats.syncp);
> +                       u64_stats_inc(&sq->stats.wake);
> +                       u64_stats_update_end(&sq->stats.syncp);
>                         netif_tx_wake_queue(txq);
>                 }
>
> @@ -3218,12 +3217,11 @@ static int virtnet_poll_tx(struct napi_struct *napi, int budget)
>         else
>                 free_old_xmit(sq, txq, !!budget);
>
> -       if (sq->vq->num_free >= MAX_SKB_FRAGS + 2) {
> -               if (netif_tx_queue_stopped(txq)) {
> -                       u64_stats_update_begin(&sq->stats.syncp);
> -                       u64_stats_inc(&sq->stats.wake);
> -                       u64_stats_update_end(&sq->stats.syncp);
> -               }
> +       if (sq->vq->num_free >= MAX_SKB_FRAGS + 2 &&
> +           netif_tx_queue_stopped(txq)) {
> +               u64_stats_update_begin(&sq->stats.syncp);
> +               u64_stats_inc(&sq->stats.wake);
> +               u64_stats_update_end(&sq->stats.syncp);
>                 netif_tx_wake_queue(txq);
>         }
>
> --
> 2.34.1
>