From patchwork Wed Feb 26 09:20:09 2014 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Qinchuanyu X-Patchwork-Id: 3722761 Return-Path: X-Original-To: patchwork-kvm@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork1.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.19.201]) by patchwork1.web.kernel.org (Postfix) with ESMTP id A65329F2F7 for ; Wed, 26 Feb 2014 09:20:57 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id A8164201D3 for ; Wed, 26 Feb 2014 09:20:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C15F220107 for ; Wed, 26 Feb 2014 09:20:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751401AbaBZJUs (ORCPT ); Wed, 26 Feb 2014 04:20:48 -0500 Received: from szxga02-in.huawei.com ([119.145.14.65]:5106 "EHLO szxga02-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751047AbaBZJUq (ORCPT ); Wed, 26 Feb 2014 04:20:46 -0500 Received: from 172.24.2.119 (EHLO szxeml205-edg.china.huawei.com) ([172.24.2.119]) by szxrg02-dlp.huawei.com (MOS 4.3.7-GA FastPath queued) with ESMTP id BQI82577; Wed, 26 Feb 2014 17:20:19 +0800 (CST) Received: from SZXEML402-HUB.china.huawei.com (10.82.67.32) by szxeml205-edg.china.huawei.com (172.24.2.58) with Microsoft SMTP Server (TLS) id 14.3.158.1; Wed, 26 Feb 2014 17:20:16 +0800 Received: from [127.0.0.1] (10.177.21.101) by szxeml402-hub.china.huawei.com (10.82.67.32) with Microsoft SMTP Server id 14.3.158.1; Wed, 26 Feb 2014 17:20:10 +0800 Message-ID: <530DB1C9.2060106@huawei.com> Date: Wed, 26 Feb 2014 17:20:09 +0800 From: Qin Chuanyu User-Agent: Mozilla/5.0 (Windows NT 6.1; rv:24.0) Gecko/20100101 Thunderbird/24.0.1 MIME-Version: 1.0 To: , "Michael S. Tsirkin" , Jason Wang , , KVM list CC: Subject: [PATCH] vhost: poll vhost_net only when tx notification is enabled X-Originating-IP: [10.177.21.101] X-CFilter-Loop: Reflected Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org X-Spam-Status: No, score=-6.9 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_HI, RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=ham version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP guest kick host base on avail_ring flags value and get perfermance improved, vhost_zerocopy_callback could do the same thing. As virtqueue_enable_cb need one more check after modifying the value of avail_ring flags, vhost also need do the same thing after vhost_enable_notify. test result list as below: guest and host: suse11sp3, netperf, intel CPU 2.4GHz +------+----------+--------+----------+--------+--------+---------+ | | old | new | +------+----------+--------+----------+--------+--------+---------+ | UDP | Gbit/s | PPS |CPU idle% | Gbit/s | PPS |CPU idle%| | 256 | 0.74805 | 321309 | 87.16 | 0.77933| 334743 | 90.71 | | 512 | 1.42 | 328475 | 87.03 | 1.44 | 333550 | 90.43 | | 1024 | 2.79 | 334426 | 89.09 | 2.81 | 336986 | 89.55 | | 1460 | 3.71 | 316215 | 87.53 | 4.02 | 342325 | 89.58 | +------+----------+--------+----------+--------+--------+---------+ Signed-off-by: Chuanyu Qin --- drivers/vhost/net.c | 13 ++++++++++++- 1 files changed, 12 insertions(+), 1 deletions(-) * in this case, the refcount after decrement will eventually reach 1. @@ -322,7 +326,8 @@ static void vhost_zerocopy_callback(struct ubuf_info *ubuf, bool success) * (the value 16 here is more or less arbitrary, it's tuned to trigger * less than 10% of times). */ - if (cnt <= 1 || !(cnt % 16)) + if ((!(vq->used_flags & VRING_USED_F_NO_NOTIFY)) + && (cnt <= 1 || !(cnt % 16))) vhost_poll_queue(&vq->poll); rcu_read_unlock_bh(); @@ -386,6 +391,12 @@ static void handle_tx(struct vhost_net *net) vhost_disable_notify(&net->dev, vq); continue; } + /* there might skb been freed between last + * vhost_zerocopy_signal_used and vhost_enable_notify, + * so one more check is needed. + */ + if (zcopy) + vhost_zerocopy_signal_used(net, vq); break; } if (in) { diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c index a0fa5de..a90f51b 100644 --- a/drivers/vhost/net.c +++ b/drivers/vhost/net.c @@ -315,6 +315,10 @@ static void vhost_zerocopy_callback(struct ubuf_info *ubuf, bool success) VHOST_DMA_DONE_LEN : VHOST_DMA_FAILED_LEN; cnt = vhost_net_ubuf_put(ubufs); + /* make sure len has been updated because handle_tx would use it + * and used_flags should also been checked. + */ + smp_mb(); /* * Trigger polling thread if guest stopped submitting new buffers: