From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jason Wang Subject: Re: [PATCH net-next v8 7/7] net: vhost: make busyloop_intr more accurate Date: Tue, 21 Aug 2018 08:47:35 +0800 Message-ID: <8460e039-d58e-85df-cef9-c87933f46cc2@redhat.com> References: <1534680686-3108-1-git-send-email-xiangxia.m.yue@gmail.com> <1534680686-3108-8-git-send-email-xiangxia.m.yue@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Cc: netdev@vger.kernel.org, virtualization@lists.linux-foundation.org To: xiangxia.m.yue@gmail.com, mst@redhat.com, makita.toshiaki@lab.ntt.co.jp Return-path: Received: from mx3-rdu2.redhat.com ([66.187.233.73]:43880 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1725736AbeHUEFh (ORCPT ); Tue, 21 Aug 2018 00:05:37 -0400 In-Reply-To: Content-Language: en-US Sender: netdev-owner@vger.kernel.org List-ID: On 2018年08月21日 08:33, Jason Wang wrote: > > > On 2018年08月19日 20:11, xiangxia.m.yue@gmail.com wrote: >> From: Tonghao Zhang >> >> The patch uses vhost_has_work_pending() to check if >> the specified handler is scheduled, because in the most case, >> vhost_has_work() return true when other side handler is added >> to worker list. Use the vhost_has_work_pending() insead of >> vhost_has_work(). >> >> Topology: >> [Host] ->linux bridge -> tap vhost-net ->[Guest] >> >> TCP_STREAM (netperf): >> * Without the patch:  38035.39 Mbps, 3.37 us mean latency >> * With the patch:     38409.44 Mbps, 3.34 us mean latency > > The improvement is not obvious as last version. Do you imply there's > some recent changes of vhost that make it faster? > I misunderstood the numbers, please ignore this. It shows less than 1% improvement. I'm not sure it's worth to do so. Can you try bi-directional pktgen to see if it has more obvious effect? Thanks > Thanks > >> >> Signed-off-by: Tonghao Zhang >> --- >>   drivers/vhost/net.c | 9 ++++++--- >>   1 file changed, 6 insertions(+), 3 deletions(-) >> >> diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c >> index db63ae2..b6939ef 100644 >> --- a/drivers/vhost/net.c >> +++ b/drivers/vhost/net.c >> @@ -487,10 +487,8 @@ static void vhost_net_busy_poll(struct vhost_net >> *net, >>       endtime = busy_clock() + busyloop_timeout; >>         while (vhost_can_busy_poll(endtime)) { >> -        if (vhost_has_work(&net->dev)) { >> -            *busyloop_intr = true; >> +        if (vhost_has_work(&net->dev)) >>               break; >> -        } >>             if ((sock_has_rx_data(sock) && >>                !vhost_vq_avail_empty(&net->dev, rvq)) || >> @@ -513,6 +511,11 @@ static void vhost_net_busy_poll(struct vhost_net >> *net, >>           !vhost_has_work_pending(&net->dev, VHOST_NET_VQ_RX)) >>           vhost_net_enable_vq(net, rvq); >>   +    if (vhost_has_work_pending(&net->dev, >> +                   poll_rx ? >> +                   VHOST_NET_VQ_RX: VHOST_NET_VQ_TX)) >> +        *busyloop_intr = true; >> + >>       mutex_unlock(&vq->mutex); >>   } > > _______________________________________________ > Virtualization mailing list > Virtualization@lists.linux-foundation.org > https://lists.linuxfoundation.org/mailman/listinfo/virtualization