Michael S. Tsirkin
2020-Jun-01 13:26 UTC
[PATCH net-next v8 7/7] net: vhost: make busyloop_intr more accurate
On Tue, Aug 21, 2018 at 08:47:35AM +0800, Jason Wang wrote:> > > On 2018?08?21? 08:33, Jason Wang wrote: > > > > > > On 2018?08?19? 20:11, xiangxia.m.yue at gmail.com wrote: > > > From: Tonghao Zhang <xiangxia.m.yue at gmail.com> > > > > > > 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? > > ThanksRight, this kind of gain is in the noise. Try measuring CPU utilization?> > Thanks > > > > > > > > Signed-off-by: Tonghao Zhang <xiangxia.m.yue at gmail.com> > > > --- > > > ? 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 at lists.linux-foundation.org > > https://lists.linuxfoundation.org/mailman/listinfo/virtualization
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