LGTM
On 2018/7/19 15:17, 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 <[email protected]> Reviewed-by: Jun Piao <[email protected]> > --- > net/9p/trans_virtio.c | 21 +++++++++++---------- > 1 file changed, 11 insertions(+), 10 deletions(-) > > diff --git a/net/9p/trans_virtio.c b/net/9p/trans_virtio.c > index 05006cb..3589864 100644 > --- a/net/9p/trans_virtio.c > +++ b/net/9p/trans_virtio.c > @@ -144,24 +144,25 @@ static void req_done(struct virtqueue *vq) > struct virtio_chan *chan = vq->vdev->priv; > unsigned int len; > struct p9_req_t *req; > + bool need_wakeup = false; > unsigned long flags; > > 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; > + spin_lock_irqsave(&chan->lock, flags); > + while ((req = virtqueue_get_buf(chan->vq, &len)) != NULL) { > + if (!chan->ring_bufs_avail) { > + chan->ring_bufs_avail = 1; > + need_wakeup = true; > } > - chan->ring_bufs_avail = 1; > - spin_unlock_irqrestore(&chan->lock, flags); > - /* Wakeup if anyone waiting for VirtIO ring space. */ > - wake_up(chan->vc_wq); > + > if (len) > p9_client_cb(chan->client, req, REQ_STATUS_RCVD); > } > + spin_unlock_irqrestore(&chan->lock, flags); > + /* Wakeup if anyone waiting for VirtIO ring space. */ > + if (need_wakeup) > + wake_up(chan->vc_wq); > } > > /** >
