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authorJason Wang <jasowang@redhat.com>2017-09-05 09:22:05 +0800
committerDavid S. Miller <davem@davemloft.net>2017-09-05 14:47:32 -0700
commit8b949bef9172ca69d918e93509a4ecb03d0355e0 (patch)
tree559ecc01be516d831c10e4660bd75e26bdafb41d /drivers/vhost
parent5482a978b962abd23f17a004e46d255d11646c20 (diff)
downloadlinux-8b949bef9172ca69d918e93509a4ecb03d0355e0.tar.bz2
vhost_net: correctly check tx avail during rx busy polling
We check tx avail through vhost_enable_notify() in the past which is wrong since it only checks whether or not guest has filled more available buffer since last avail idx synchronization which was just done by vhost_vq_avail_empty() before. What we really want is checking pending buffers in the avail ring. Fix this by calling vhost_vq_avail_empty() instead. This issue could be noticed by doing netperf TCP_RR benchmark as client from guest (but not host). With this fix, TCP_RR from guest to localhost restores from 1375.91 trans per sec to 55235.28 trans per sec on my laptop (Intel(R) Core(TM) i7-5600U CPU @ 2.60GHz). Fixes: 030881372460 ("vhost_net: basic polling support") Signed-off-by: Jason Wang <jasowang@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'drivers/vhost')
-rw-r--r--drivers/vhost/net.c7
1 files changed, 6 insertions, 1 deletions
diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c
index 8d2bcae53a2e..58585ec8699e 100644
--- a/drivers/vhost/net.c
+++ b/drivers/vhost/net.c
@@ -635,8 +635,13 @@ static int vhost_net_rx_peek_head_len(struct vhost_net *net, struct sock *sk)
preempt_enable();
- if (vhost_enable_notify(&net->dev, vq))
+ if (!vhost_vq_avail_empty(&net->dev, vq))
vhost_poll_queue(&vq->poll);
+ else if (unlikely(vhost_enable_notify(&net->dev, vq))) {
+ vhost_disable_notify(&net->dev, vq);
+ vhost_poll_queue(&vq->poll);
+ }
+
mutex_unlock(&vq->mutex);
len = peek_head_len(rvq, sk);