From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jason Wang Subject: Re: [PATCH net-next v7 3/4] net: vhost: factor out busy polling logic to vhost_net_busy_poll() Date: Fri, 3 Aug 2018 11:44:11 +0800 Message-ID: References: <1533092454-37196-1-git-send-email-xiangxia.m.yue@gmail.com> <1533092454-37196-4-git-send-email-xiangxia.m.yue@gmail.com> <30e62749-3cbd-ae88-6582-c20087884b20@redhat.com> <3272c3b4-a44c-8554-329e-8a5e1a59aafd@redhat.com> <90c0deec-6a7b-9787-b62f-7ea76a5cbd7c@redhat.com> <74edb26a-e715-cb49-4e52-62e4b45638d1@lab.ntt.co.jp> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Cc: mst@redhat.com, virtualization@lists.linux-foundation.org, Linux Kernel Network Developers To: Toshiaki Makita , Tonghao Zhang Return-path: Received: from mx3-rdu2.redhat.com ([66.187.233.73]:58254 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726128AbeHCFid (ORCPT ); Fri, 3 Aug 2018 01:38:33 -0400 In-Reply-To: <74edb26a-e715-cb49-4e52-62e4b45638d1@lab.ntt.co.jp> Content-Language: en-US Sender: netdev-owner@vger.kernel.org List-ID: On 2018年08月03日 11:32, Toshiaki Makita wrote: > On 2018/08/03 12:07, Jason Wang wrote: >> 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. >>>> >> 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(). > You are right, but what I wanted to say is vhost_net_enable_vq() should > be needed (I was talking about what would happen if > vhost_net_enable_vq() were removed). Also, I think we should move > vhost_net_enable_vq() from vhost_net_busy_poll() to this last "else" > block because this is the case where rx wakeups is required. > Anyway this part will be refactored so let's see what this code will > look like in next version. > I get your point. Thanks