LGTM
On 2018/7/17 19:03, jiangyiwen wrote:
> When client has multiple threads that issue io requests
> all the time, and the server has a very good performance,
> it may cause cpu is running in the irq context for a long
> time because it can check virtqueue has buf in the *while*
> loop.
>
> So we should keep chan->lock in the whole loop.
>
> Signed-off-by: Yiwen Jiang <jiangyi...@huawei.com>
Reviewed-by: Jun Piao <piao...@huawei.com>
> ---
> net/9p/trans_virtio.c | 17 ++++++-----------
> 1 file changed, 6 insertions(+), 11 deletions(-)
>
> diff --git a/net/9p/trans_virtio.c b/net/9p/trans_virtio.c
> index 05006cb..e5fea8b 100644
> --- a/net/9p/trans_virtio.c
> +++ b/net/9p/trans_virtio.c
> @@ -148,20 +148,15 @@ static void req_done(struct virtqueue *vq)
>
> p9_debug(P9_DEBUG_TRANS, ": request done\n");
>
> - while (1) {
> - spin_lock_irqsave(&chan->lock, flags);
> - req = virtqueue_get_buf(chan->vq, &len);
> - if (req == NULL) {
> - spin_unlock_irqrestore(&chan->lock, flags);
> - break;
> - }
> - chan->ring_bufs_avail = 1;
> - spin_unlock_irqrestore(&chan->lock, flags);
> - /* Wakeup if anyone waiting for VirtIO ring space. */
> - wake_up(chan->vc_wq);
> + spin_lock_irqsave(&chan->lock, flags);
> + while ((req = virtqueue_get_buf(chan->vq, &len)) != NULL) {
> if (len)
> p9_client_cb(chan->client, req, REQ_STATUS_RCVD);
> }
> + chan->ring_bufs_avail = 1;
> + spin_unlock_irqrestore(&chan->lock, flags);
> + /* Wakeup if anyone waiting for VirtIO ring space. */
> + wake_up(chan->vc_wq);
> }
>
> /**
>
