* Re: [PATCH v4] virtio_net: suppress cpu stall when free_unused_bufs [not found] <1683167226-7012-1-git-send-email-wangwenliang.1995@bytedance.com> @ 2023-05-04 7:06 ` Michael S. Tsirkin 2023-05-05 3:28 ` Jason Wang 1 sibling, 0 replies; 9+ messages in thread From: Michael S. Tsirkin @ 2023-05-04 7:06 UTC (permalink / raw) To: Wenliang Wang Cc: xuanzhuo, willemdebruijn.kernel, netdev, linux-kernel, zhengqi.arch, virtualization, edumazet, kuba, pabeni, davem On Thu, May 04, 2023 at 10:27:06AM +0800, Wenliang Wang 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.1995@bytedance.com> Acked-by: Michael S. Tsirkin <mst@redhat.com> Probably a good idea for stable, too. > --- > 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(); > } > > 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 _______________________________________________ Virtualization mailing list Virtualization@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/virtualization ^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH v4] virtio_net: suppress cpu stall when free_unused_bufs [not found] <1683167226-7012-1-git-send-email-wangwenliang.1995@bytedance.com> 2023-05-04 7:06 ` [PATCH v4] virtio_net: suppress cpu stall when free_unused_bufs Michael S. Tsirkin @ 2023-05-05 3:28 ` Jason Wang 2023-05-06 2:04 ` Xuan Zhuo 2023-05-07 13:34 ` Michael S. Tsirkin 1 sibling, 2 replies; 9+ messages in thread From: Jason Wang @ 2023-05-05 3:28 UTC (permalink / raw) To: Wenliang Wang Cc: xuanzhuo, willemdebruijn.kernel, mst, netdev, linux-kernel, zhengqi.arch, virtualization, edumazet, kuba, pabeni, davem On Thu, May 4, 2023 at 10:27 AM Wenliang Wang <wangwenliang.1995@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.1995@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? 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 > _______________________________________________ Virtualization mailing list Virtualization@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/virtualization ^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH v4] virtio_net: suppress cpu stall when free_unused_bufs 2023-05-05 3:28 ` Jason Wang @ 2023-05-06 2:04 ` Xuan Zhuo 2023-05-07 13:34 ` Michael S. Tsirkin 1 sibling, 0 replies; 9+ messages in thread From: Xuan Zhuo @ 2023-05-06 2:04 UTC (permalink / raw) To: Jason Wang Cc: willemdebruijn.kernel, Wenliang Wang, mst, netdev, linux-kernel, zhengqi.arch, virtualization, edumazet, kuba, pabeni, davem On Fri, 5 May 2023 11:28:25 +0800, Jason Wang <jasowang@redhat.com> wrote: > On Thu, May 4, 2023 at 10:27 AM Wenliang Wang > <wangwenliang.1995@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.1995@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 > > > _______________________________________________ Virtualization mailing list Virtualization@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/virtualization ^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH v4] virtio_net: suppress cpu stall when free_unused_bufs 2023-05-05 3:28 ` Jason Wang 2023-05-06 2:04 ` Xuan Zhuo @ 2023-05-07 13:34 ` Michael S. Tsirkin 2023-05-08 3:12 ` Jason Wang 1 sibling, 1 reply; 9+ messages in thread From: Michael S. Tsirkin @ 2023-05-07 13:34 UTC (permalink / raw) To: Jason Wang Cc: xuanzhuo, willemdebruijn.kernel, Wenliang Wang, netdev, linux-kernel, zhengqi.arch, virtualization, edumazet, kuba, pabeni, davem On Fri, May 05, 2023 at 11:28:25AM +0800, Jason Wang wrote: > On Thu, May 4, 2023 at 10:27 AM Wenliang Wang > <wangwenliang.1995@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.1995@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? > > Thanks it does in that a very large queue is still just 64k in size. we might however have 64k of these queues. > > } > > > > 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 > > _______________________________________________ Virtualization mailing list Virtualization@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/virtualization ^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH v4] virtio_net: suppress cpu stall when free_unused_bufs 2023-05-07 13:34 ` Michael S. Tsirkin @ 2023-05-08 3:12 ` Jason Wang 2023-05-08 6:07 ` Michael S. Tsirkin 0 siblings, 1 reply; 9+ messages in thread From: Jason Wang @ 2023-05-08 3:12 UTC (permalink / raw) To: Michael S. Tsirkin Cc: xuanzhuo, willemdebruijn.kernel, Wenliang Wang, netdev, linux-kernel, zhengqi.arch, virtualization, edumazet, kuba, pabeni, davem 在 2023/5/7 21:34, Michael S. Tsirkin 写道: > On Fri, May 05, 2023 at 11:28:25AM +0800, Jason Wang wrote: >> On Thu, May 4, 2023 at 10:27 AM Wenliang Wang >> <wangwenliang.1995@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.1995@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? >> >> Thanks > > it does in that a very large queue is still just 64k in size. > we might however have 64k of these queues. Ok, but we have other similar loops especially the refill, I think we may need cond_resched() there as well. 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 >>> _______________________________________________ Virtualization mailing list Virtualization@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/virtualization ^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH v4] virtio_net: suppress cpu stall when free_unused_bufs 2023-05-08 3:12 ` Jason Wang @ 2023-05-08 6:07 ` Michael S. Tsirkin 2023-05-08 6:13 ` Jason Wang 0 siblings, 1 reply; 9+ messages in thread From: Michael S. Tsirkin @ 2023-05-08 6:07 UTC (permalink / raw) To: Jason Wang Cc: xuanzhuo, willemdebruijn.kernel, Wenliang Wang, netdev, linux-kernel, zhengqi.arch, virtualization, edumazet, kuba, pabeni, davem On Mon, May 08, 2023 at 11:12:03AM +0800, Jason Wang wrote: > > 在 2023/5/7 21:34, Michael S. Tsirkin 写道: > > On Fri, May 05, 2023 at 11:28:25AM +0800, Jason Wang wrote: > > > On Thu, May 4, 2023 at 10:27 AM Wenliang Wang > > > <wangwenliang.1995@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.1995@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? > > > > > > Thanks > > > > it does in that a very large queue is still just 64k in size. > > we might however have 64k of these queues. > > > Ok, but we have other similar loops especially the refill, I think we may > need cond_resched() there as well. > > Thanks > Refill is already per vq isn't it? > > > > > > } > > > > > > > > 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 > > > > _______________________________________________ Virtualization mailing list Virtualization@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/virtualization ^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH v4] virtio_net: suppress cpu stall when free_unused_bufs 2023-05-08 6:07 ` Michael S. Tsirkin @ 2023-05-08 6:13 ` Jason Wang 2023-05-08 6:47 ` Michael S. Tsirkin 0 siblings, 1 reply; 9+ messages in thread From: Jason Wang @ 2023-05-08 6:13 UTC (permalink / raw) To: Michael S. Tsirkin Cc: xuanzhuo, willemdebruijn.kernel, Wenliang Wang, netdev, linux-kernel, zhengqi.arch, virtualization, edumazet, kuba, pabeni, davem On Mon, May 8, 2023 at 2:08 PM Michael S. Tsirkin <mst@redhat.com> wrote: > > On Mon, May 08, 2023 at 11:12:03AM +0800, Jason Wang wrote: > > > > 在 2023/5/7 21:34, Michael S. Tsirkin 写道: > > > On Fri, May 05, 2023 at 11:28:25AM +0800, Jason Wang wrote: > > > > On Thu, May 4, 2023 at 10:27 AM Wenliang Wang > > > > <wangwenliang.1995@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.1995@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? > > > > > > > > Thanks > > > > > > it does in that a very large queue is still just 64k in size. > > > we might however have 64k of these queues. > > > > > > Ok, but we have other similar loops especially the refill, I think we may > > need cond_resched() there as well. > > > > Thanks > > > > Refill is already per vq isn't it? Not for the refill_work(). 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 > > > > > > _______________________________________________ Virtualization mailing list Virtualization@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/virtualization ^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH v4] virtio_net: suppress cpu stall when free_unused_bufs 2023-05-08 6:13 ` Jason Wang @ 2023-05-08 6:47 ` Michael S. Tsirkin 2023-05-09 3:14 ` Jason Wang 0 siblings, 1 reply; 9+ messages in thread From: Michael S. Tsirkin @ 2023-05-08 6:47 UTC (permalink / raw) To: Jason Wang Cc: xuanzhuo, willemdebruijn.kernel, Wenliang Wang, netdev, linux-kernel, zhengqi.arch, virtualization, edumazet, kuba, pabeni, davem On Mon, May 08, 2023 at 02:13:42PM +0800, Jason Wang wrote: > On Mon, May 8, 2023 at 2:08 PM Michael S. Tsirkin <mst@redhat.com> wrote: > > > > On Mon, May 08, 2023 at 11:12:03AM +0800, Jason Wang wrote: > > > > > > 在 2023/5/7 21:34, Michael S. Tsirkin 写道: > > > > On Fri, May 05, 2023 at 11:28:25AM +0800, Jason Wang wrote: > > > > > On Thu, May 4, 2023 at 10:27 AM Wenliang Wang > > > > > <wangwenliang.1995@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.1995@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? > > > > > > > > > > Thanks > > > > > > > > it does in that a very large queue is still just 64k in size. > > > > we might however have 64k of these queues. > > > > > > > > > Ok, but we have other similar loops especially the refill, I think we may > > > need cond_resched() there as well. > > > > > > Thanks > > > > > > > Refill is already per vq isn't it? > > Not for the refill_work(). > > Thanks Good point, refill_work probably needs cond_resched, too. And I guess virtnet_open? > > > > > > > > > > > > > > } > > > > > > > > > > > > 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 > > > > > > > > _______________________________________________ Virtualization mailing list Virtualization@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/virtualization ^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH v4] virtio_net: suppress cpu stall when free_unused_bufs 2023-05-08 6:47 ` Michael S. Tsirkin @ 2023-05-09 3:14 ` Jason Wang 0 siblings, 0 replies; 9+ messages in thread From: Jason Wang @ 2023-05-09 3:14 UTC (permalink / raw) To: Michael S. Tsirkin Cc: xuanzhuo, willemdebruijn.kernel, Wenliang Wang, netdev, linux-kernel, zhengqi.arch, virtualization, edumazet, kuba, pabeni, davem On Mon, May 8, 2023 at 2:47 PM Michael S. Tsirkin <mst@redhat.com> wrote: > > On Mon, May 08, 2023 at 02:13:42PM +0800, Jason Wang wrote: > > On Mon, May 8, 2023 at 2:08 PM Michael S. Tsirkin <mst@redhat.com> wrote: > > > > > > On Mon, May 08, 2023 at 11:12:03AM +0800, Jason Wang wrote: > > > > > > > > 在 2023/5/7 21:34, Michael S. Tsirkin 写道: > > > > > On Fri, May 05, 2023 at 11:28:25AM +0800, Jason Wang wrote: > > > > > > On Thu, May 4, 2023 at 10:27 AM Wenliang Wang > > > > > > <wangwenliang.1995@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.1995@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? > > > > > > > > > > > > Thanks > > > > > > > > > > it does in that a very large queue is still just 64k in size. > > > > > we might however have 64k of these queues. > > > > > > > > > > > > Ok, but we have other similar loops especially the refill, I think we may > > > > need cond_resched() there as well. > > > > > > > > Thanks > > > > > > > > > > Refill is already per vq isn't it? > > > > Not for the refill_work(). > > > > Thanks > > Good point, refill_work probably needs cond_resched, too. > And I guess virtnet_open? Yes, let me draft a patch. 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 > > > > > > > > > > > _______________________________________________ Virtualization mailing list Virtualization@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/virtualization ^ permalink raw reply [flat|nested] 9+ messages in thread
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Thread overview: 9+ messages (download: mbox.gz follow: Atom feed
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2023-05-04 7:06 ` [PATCH v4] virtio_net: suppress cpu stall when free_unused_bufs Michael S. Tsirkin
2023-05-05 3:28 ` Jason Wang
2023-05-06 2:04 ` Xuan Zhuo
2023-05-07 13:34 ` Michael S. Tsirkin
2023-05-08 3:12 ` Jason Wang
2023-05-08 6:07 ` Michael S. Tsirkin
2023-05-08 6:13 ` Jason Wang
2023-05-08 6:47 ` Michael S. Tsirkin
2023-05-09 3:14 ` Jason Wang
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