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Message-Id: <1464590874-39539-3-git-send-email-jasowang@redhat.com> Date: Mon, 30 May 2016 02:47:54 -0400 From: Jason Wang <jasowang@...hat.com> To: mst@...hat.com, kvm@...r.kernel.org, virtualization@...ts.linux-foundation.org, netdev@...r.kernel.org, linux-kernel@...r.kernel.org Cc: Jason Wang <jasowang@...hat.com> Subject: [PATCH V2 2/2] vhost_net: conditionally enable tx polling We always poll tx for socket, this is sub optimal since: - it will be only used when we exceed the sndbuf of the socket. - since we use two independent polls for tx and vq, this will slightly increase the waitqueue traversing time and more important, vhost could not benefit from commit 9e641bdcfa4ef4d6e2fbaa59c1be0ad5d1551fd5 ("net-tun: restructure tun_do_read for better sleep/wakeup efficiency") even if we've stopped rx polling during handle_rx since tx poll were still left in the waitqueue. Fix this by conditionally enable tx polling only when -EAGAIN were met. Test shows about 8% improvement on guest rx pps. Before: ~1350000 After: ~1460000 Signed-off-by: Jason Wang <jasowang@...hat.com> --- drivers/vhost/net.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c index e91603b..5a05fa0 100644 --- a/drivers/vhost/net.c +++ b/drivers/vhost/net.c @@ -378,6 +378,7 @@ static void handle_tx(struct vhost_net *net) goto out; vhost_disable_notify(&net->dev, vq); + vhost_net_disable_vq(net, vq); hdr_size = nvq->vhost_hlen; zcopy = nvq->ubufs; @@ -459,6 +460,8 @@ static void handle_tx(struct vhost_net *net) % UIO_MAXIOV; } vhost_discard_vq_desc(vq, 1); + if (err == -EAGAIN) + vhost_net_enable_vq(net, vq); break; } if (err != len) -- 1.8.3.1
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