On Fri, 5 May 2023 11:28:25 +0800, Jason Wang <jasow...@redhat.com> wrote:
> On Thu, May 4, 2023 at 10:27 AM Wenliang Wang
> <wangwenliang.1...@bytedance.com> wrote:
> >
> > For multi-queue and large ring-size use case, the following error
> > occurred when free_unused_bufs:
> > rcu: INFO: rcu_sched self-detected stall on CPU.
> >
> > Fixes: 986a4f4d452d ("virtio_net: multiqueue support")
> > Signed-off-by: Wenliang Wang <wangwenliang.1...@bytedance.com>
> > ---
> > v2:
> > -add need_resched check.
> > -apply same logic to sq.
> > v3:
> > -use cond_resched instead.
> > v4:
> > -add fixes tag
> > ---
> > drivers/net/virtio_net.c | 2 ++
> > 1 file changed, 2 insertions(+)
> >
> > diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> > index 8d8038538fc4..a12ae26db0e2 100644
> > --- a/drivers/net/virtio_net.c
> > +++ b/drivers/net/virtio_net.c
> > @@ -3560,12 +3560,14 @@ static void free_unused_bufs(struct virtnet_info
> > *vi)
> > struct virtqueue *vq = vi->sq[i].vq;
> > while ((buf = virtqueue_detach_unused_buf(vq)) != NULL)
> > virtnet_sq_free_unused_buf(vq, buf);
> > + cond_resched();
>
> Does this really address the case when the virtqueue is very large?
Yes, I also have this question. I think cond_resched() should be called every
time a certain number of buffers are processed.
Thanks.
>
> Thanks
>
> > }
> >
> > for (i = 0; i < vi->max_queue_pairs; i++) {
> > struct virtqueue *vq = vi->rq[i].vq;
> > while ((buf = virtqueue_detach_unused_buf(vq)) != NULL)
> > virtnet_rq_free_unused_buf(vq, buf);
> > + cond_resched();
> > }
> > }
> >
> > --
> > 2.20.1
> >
>
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