On 2018年08月19日 20:11, [email protected] wrote:
From: Tonghao Zhang <[email protected]>

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?

Thanks


Signed-off-by: Tonghao Zhang <[email protected]>
---
  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);
  }

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