On Thu, Jul 20, 2023 at 01:26:20PM -0700, Shannon Nelson wrote:
> On 7/20/23 1:38 AM, Jason Wang wrote:
> >
> > Adding cond_resched() to the command waiting loop for a better
> > co-operation with the scheduler. This allows to give CPU a breath to
> > run other task(workqueue) instead of busy looping when preemption is
> > not allowed on a device whose CVQ might be slow.
> >
> > Signed-off-by: Jason Wang <jasowang@xxxxxxxxxx>
>
> This still leaves hung processes, but at least it doesn't pin the CPU any
> more. Thanks.
> Reviewed-by: Shannon Nelson <shannon.nelson@xxxxxxx>
>
I'd like to see a full solution
1- block until interrupt
2- still handle surprise removal correctly by waking in that case
> > ---
> > drivers/net/virtio_net.c | 4 +++-
> > 1 file changed, 3 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> > index 9f3b1d6ac33d..e7533f29b219 100644
> > --- a/drivers/net/virtio_net.c
> > +++ b/drivers/net/virtio_net.c
> > @@ -2314,8 +2314,10 @@ static bool virtnet_send_command(struct virtnet_info *vi, u8 class, u8 cmd,
> > * into the hypervisor, so the request should be handled immediately.
> > */
> > while (!virtqueue_get_buf(vi->cvq, &tmp) &&
> > - !virtqueue_is_broken(vi->cvq))
> > + !virtqueue_is_broken(vi->cvq)) {
> > + cond_resched();
> > cpu_relax();
> > + }
> >
> > return vi->ctrl->status == VIRTIO_NET_OK;
> > }
> > --
> > 2.39.3
> >
> > _______________________________________________
> > Virtualization mailing list
> > Virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx
> > https://lists.linuxfoundation.org/mailman/listinfo/virtualization
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