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Message-ID: <252ee222-f918-426e-68ef-b3710a60662e@bytedance.com>
Date: Thu, 27 Apr 2023 15:02:26 +0800
From: Wenliang Wang <wangwenliang.1995@...edance.com>
To: Xuan Zhuo <xuanzhuo@...ux.alibaba.com>
Cc: virtualization@...ts.linux-foundation.org, netdev@...r.kernel.org,
linux-kernel@...r.kernel.org, mst@...hat.com, jasowang@...hat.com,
davem@...emloft.net, edumazet@...gle.com, kuba@...nel.org,
pabeni@...hat.com
Subject: Re: [PATCH] virtio_net: suppress cpu stall when free_unused_bufs
On 4/27/23 2:20 PM, Xuan Zhuo wrote:
> On Thu, 27 Apr 2023 12:34:33 +0800, Wenliang Wang <wangwenliang.1995@...edance.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@...edance.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.
>
> Thanks.
>
>
>> }
>> }
>>
>> --
>> 2.20.1
>>
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