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From: "Michael S. Tsirkin" <mst@redhat.com>
To: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
Cc: pabeni@redhat.com, netdev@vger.kernel.org,
	linux-kernel@vger.kernel.org,
	virtualization@lists.linux-foundation.org, edumazet@google.com,
	kuba@kernel.org, Wenliang Wang <wangwenliang.1995@bytedance.com>,
	davem@davemloft.net
Subject: Re: [PATCH] virtio_net: suppress cpu stall when free_unused_bufs
Date: Thu, 27 Apr 2023 04:12:44 -0400	[thread overview]
Message-ID: <20230427041206-mutt-send-email-mst@kernel.org> (raw)
In-Reply-To: <1682579624.5395834-1-xuanzhuo@linux.alibaba.com>

On Thu, Apr 27, 2023 at 03:13:44PM +0800, Xuan Zhuo wrote:
> On Thu, 27 Apr 2023 15:02:26 +0800, Wenliang Wang <wangwenliang.1995@bytedance.com> wrote:
> >
> >
> > On 4/27/23 2:20 PM, Xuan Zhuo wrote:
> > > On Thu, 27 Apr 2023 12:34:33 +0800, Wenliang Wang <wangwenliang.1995@bytedance.com> wrote:
> > >> For multi-queue and large rx-ring-size use case, the following error
> > >
> > > Cound you give we one number for example?
> >
> > 128 queues and 16K queue_size is typical.
> >
> > >
> > >> occurred when free_unused_bufs:
> > >> rcu: INFO: rcu_sched self-detected stall on CPU.
> > >>
> > >> Signed-off-by: Wenliang Wang <wangwenliang.1995@bytedance.com>
> > >> ---
> > >>   drivers/net/virtio_net.c | 1 +
> > >>   1 file changed, 1 insertion(+)
> > >>
> > >> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> > >> index ea1bd4bb326d..21d8382fd2c7 100644
> > >> --- a/drivers/net/virtio_net.c
> > >> +++ b/drivers/net/virtio_net.c
> > >> @@ -3565,6 +3565,7 @@ static void free_unused_bufs(struct virtnet_info *vi)
> > >>   		struct virtqueue *vq = vi->rq[i].vq;
> > >>   		while ((buf = virtqueue_detach_unused_buf(vq)) != NULL)
> > >>   			virtnet_rq_free_unused_buf(vq, buf);
> > >> +		schedule();
> > >
> > > Just for rq?
> > >
> > > Do we need to do the same thing for sq?
> > Rq buffers are pre-allocated, take seconds to free rq unused buffers.
> >
> > Sq unused buffers are much less, so do the same for sq is optional.
> 
> I got.
> 
> I think we should look for a way, compatible with the less queues or the smaller
> rings. Calling schedule() directly may be not a good way.
> 
> Thanks.

Why isn't it a good way?

> 
> >
> > >
> > > Thanks.
> > >
> > >
> > >>   	}
> > >>   }
> > >>
> > >> --
> > >> 2.20.1
> > >>

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Virtualization@lists.linux-foundation.org
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WARNING: multiple messages have this Message-ID (diff)
From: "Michael S. Tsirkin" <mst@redhat.com>
To: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
Cc: Wenliang Wang <wangwenliang.1995@bytedance.com>,
	virtualization@lists.linux-foundation.org,
	netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
	jasowang@redhat.com, davem@davemloft.net, edumazet@google.com,
	kuba@kernel.org, pabeni@redhat.com
Subject: Re: [PATCH] virtio_net: suppress cpu stall when free_unused_bufs
Date: Thu, 27 Apr 2023 04:12:44 -0400	[thread overview]
Message-ID: <20230427041206-mutt-send-email-mst@kernel.org> (raw)
In-Reply-To: <1682579624.5395834-1-xuanzhuo@linux.alibaba.com>

On Thu, Apr 27, 2023 at 03:13:44PM +0800, Xuan Zhuo wrote:
> On Thu, 27 Apr 2023 15:02:26 +0800, Wenliang Wang <wangwenliang.1995@bytedance.com> wrote:
> >
> >
> > On 4/27/23 2:20 PM, Xuan Zhuo wrote:
> > > On Thu, 27 Apr 2023 12:34:33 +0800, Wenliang Wang <wangwenliang.1995@bytedance.com> wrote:
> > >> For multi-queue and large rx-ring-size use case, the following error
> > >
> > > Cound you give we one number for example?
> >
> > 128 queues and 16K queue_size is typical.
> >
> > >
> > >> occurred when free_unused_bufs:
> > >> rcu: INFO: rcu_sched self-detected stall on CPU.
> > >>
> > >> Signed-off-by: Wenliang Wang <wangwenliang.1995@bytedance.com>
> > >> ---
> > >>   drivers/net/virtio_net.c | 1 +
> > >>   1 file changed, 1 insertion(+)
> > >>
> > >> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> > >> index ea1bd4bb326d..21d8382fd2c7 100644
> > >> --- a/drivers/net/virtio_net.c
> > >> +++ b/drivers/net/virtio_net.c
> > >> @@ -3565,6 +3565,7 @@ static void free_unused_bufs(struct virtnet_info *vi)
> > >>   		struct virtqueue *vq = vi->rq[i].vq;
> > >>   		while ((buf = virtqueue_detach_unused_buf(vq)) != NULL)
> > >>   			virtnet_rq_free_unused_buf(vq, buf);
> > >> +		schedule();
> > >
> > > Just for rq?
> > >
> > > Do we need to do the same thing for sq?
> > Rq buffers are pre-allocated, take seconds to free rq unused buffers.
> >
> > Sq unused buffers are much less, so do the same for sq is optional.
> 
> I got.
> 
> I think we should look for a way, compatible with the less queues or the smaller
> rings. Calling schedule() directly may be not a good way.
> 
> Thanks.

Why isn't it a good way?

> 
> >
> > >
> > > Thanks.
> > >
> > >
> > >>   	}
> > >>   }
> > >>
> > >> --
> > >> 2.20.1
> > >>


  reply	other threads:[~2023-04-27  8:12 UTC|newest]

Thread overview: 21+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-04-27  4:34 [PATCH] virtio_net: suppress cpu stall when free_unused_bufs Wenliang Wang
2023-04-27  6:20 ` Xuan Zhuo
2023-04-27  6:20   ` Xuan Zhuo
2023-04-27  7:02   ` Wenliang Wang
2023-04-27  7:13     ` Xuan Zhuo
2023-04-27  7:13       ` Xuan Zhuo
2023-04-27  8:12       ` Michael S. Tsirkin [this message]
2023-04-27  8:12         ` Michael S. Tsirkin
2023-04-27  8:13         ` Xuan Zhuo
2023-04-27  8:13           ` Xuan Zhuo
2023-04-27  8:23           ` Michael S. Tsirkin
2023-04-27  8:23             ` Michael S. Tsirkin
2023-04-27  8:49             ` Wenliang Wang
2023-04-27  8:51               ` Xuan Zhuo
2023-04-27  8:51                 ` Xuan Zhuo
2023-04-27 10:46                 ` [PATCH v2] " Wenliang Wang
2023-04-28  1:09                   ` Michael S. Tsirkin
2023-04-28  1:09                     ` Michael S. Tsirkin
2023-04-27 10:45             ` [PATCH] " Qi Zheng
2023-04-28 13:56               ` Willem de Bruijn
2023-04-28 13:56                 ` Willem de Bruijn

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