On Mon, Sep 05, 2022 at 12:53:41PM +0800, 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.
>
> What's more important. This is a must for some vDPA parent to work
> since control virtqueue is emulated via a workqueue for those parents.
>
> Fixes: bda324fd037a ("vdpasim: control virtqueue support")
That's a weird commit to fix. so it fixes the simulator?
> Signed-off-by: Jason Wang <jasowang@xxxxxxxxxx>
> ---
> 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 ece00b84e3a7..169368365d6a 100644
> --- a/drivers/net/virtio_net.c
> +++ b/drivers/net/virtio_net.c
> @@ -2000,8 +2000,10 @@ 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();
> + }
with cond_resched do we still need cpu_relax?
> return vi->ctrl->status == VIRTIO_NET_OK;
> }
> --
> 2.25.1
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