From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757437AbcFAF5F (ORCPT ); Wed, 1 Jun 2016 01:57:05 -0400 Received: from mx1.redhat.com ([209.132.183.28]:46829 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757381AbcFAF4n (ORCPT ); Wed, 1 Jun 2016 01:56:43 -0400 From: Jason Wang To: mst@redhat.com, kvm@vger.kernel.org, virtualization@lists.linux-foundation.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org Cc: Jason Wang Subject: [PATCH V3 2/2] vhost_net: conditionally enable tx polling Date: Wed, 1 Jun 2016 01:56:34 -0400 Message-Id: <1464760594-30326-3-git-send-email-jasowang@redhat.com> In-Reply-To: <1464760594-30326-1-git-send-email-jasowang@redhat.com> References: <1464760594-30326-1-git-send-email-jasowang@redhat.com> X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.38]); Wed, 01 Jun 2016 05:56:42 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 --- drivers/vhost/net.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c index 1d3e45f..e75ffcc 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