# \[PATCH net-next v8 7/7\] net: vhost: make busyloop\_intr more accurate - From: \ - Date: 2018-08-19 15:23:19 - List: netdev - Page: https://ratatoskr.run/netdev/2018/08/11106197 - Thread: https://ratatoskr.run/netdev/2018/08/11106190/t.md ```text 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 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); } -- 1.8.3.1 ```