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Date: Fri, 3 Aug 2018 10:38:36 +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 17:57, Toshiaki Makita wrote: > On 2018/08/02 18:23, Jason Wang wrote: >> On 2018年08月02日 16:41, Toshiaki Makita wrote: >>> On 2018/08/02 17:18, Jason Wang wrote: >>>> On 2018年08月01日 17:52, Tonghao Zhang wrote: >>>>>> +static void vhost_net_busy_poll_check(struct vhost_net *net, >>>>>> + struct vhost_virtqueue *rvq, >>>>>> + struct vhost_virtqueue *tvq, >>>>>> + bool rx) >>>>>> +{ >>>>>> + struct socket *sock = rvq->private_data; >>>>>> + >>>>>> + if (rx) >>>>>> + vhost_net_busy_poll_try_queue(net, tvq); >>>>>> + else if (sock && sk_has_rx_data(sock->sk)) >>>>>> + vhost_net_busy_poll_try_queue(net, rvq); >>>>>> + else { >>>>>> + /* On tx here, sock has no rx data, so we >>>>>> + * will wait for sock wakeup for rx, and >>>>>> + * vhost_enable_notify() is not needed. */ >>>>> A possible case is we do have rx data but guest does not refill the rx >>>>> queue. In this case we may lose notifications from guest. >>>> Yes, should consider this case. thanks. >>> I'm a bit confused. Isn't this covered by the previous >>> "else if (sock && sk_has_rx_data(...))" block? >> The problem is it does nothing if vhost_vq_avail_empty() is true and >> vhost_enble_notify() is false. > If vhost_enable_notify() is false, guest will eventually kicks vq, no? > Yes, you are right. Thanks
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