Messages in this thread | ![/](/images/icornerl.gif) | | Date | Fri, 21 Jul 2023 16:37:00 +0200 | Subject | Re: [PATCH net-next v4 2/2] virtio-net: add cond_resched() to the command waiting loop | From | Maxime Coquelin <> |
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On 7/20/23 23:02, Michael S. Tsirkin wrote: > 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@redhat.com> >> >> This still leaves hung processes, but at least it doesn't pin the CPU any >> more. Thanks. >> Reviewed-by: Shannon Nelson <shannon.nelson@amd.com> >> > > I'd like to see a full solution > 1- block until interrupt
Would it make sense to also have a timeout? And when timeout expires, set FAILED bit in device status?
> 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@lists.linux-foundation.org >>> https://lists.linuxfoundation.org/mailman/listinfo/virtualization >
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