netdev - Re: [PATCH net-next v7 3/4] net: vhost: factor out busy polling logic to vhost_net_busy

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Message-ID: <90c0deec-6a7b-9787-b62f-7ea76a5cbd7c@redhat.com>
Date:   Fri, 3 Aug 2018 11:07:00 +0800
From:   Jason Wang <jasowang@...hat.com>
To:     Toshiaki Makita <makita.toshiaki@....ntt.co.jp>,
        Tonghao Zhang <xiangxia.m.yue@...il.com>
Cc:     mst@...hat.com, virtualization@...ts.linux-foundation.org,
        Linux Kernel Network Developers <netdev@...r.kernel.org>
Subject: Re: [PATCH net-next v7 3/4] net: vhost: factor out busy polling logic
 to vhost_net_busy_poll()



On 2018年08月02日 17:23, Jason Wang wrote:
>>>>>>
>>>>> No need to enable rx virtqueue, if we are sure handle_rx() will be
>>>>> called soon.
>>>> If we disable rx virtqueue in handle_tx and don't send packets from
>>>> guest anymore(handle_tx is not called), so we can wake up for sock rx.
>>>> so the network is broken.
>>> Not sure I understand here. I mean is we schedule work for handle_rx(),
>>> there's no need to enable it since handle_rx() will do this for us.
>> Looks like in the last "else" block in vhost_net_busy_poll_check() we
>> need to enable vq since in that case we have no rx data and handle_rx()
>> is not scheduled.
>>
>
> Yes.
>
> Thanks 

Rethink about this, looks not. We enable rx wakeups in this case, so if 
there's pending data, handle_rx() will be schedule after 
vhost_net_enable_vq().

Thanks