From mboxrd@z Thu Jan 1 00:00:00 1970 From: Qin Chuanyu Subject: [PATCH] vhost: make vhost_zerocopy_callback more efficient by poll_queue base on vhost status Date: Wed, 26 Feb 2014 11:59:38 +0800 Message-ID: <530D66AA.5070004@huawei.com> Mime-Version: 1.0 Content-Type: text/plain; charset="ISO-8859-1"; format=flowed Content-Transfer-Encoding: 7bit Cc: KVM list , To: , "Michael S. Tsirkin" , Jason Wang Return-path: Received: from szxga03-in.huawei.com ([119.145.14.66]:13416 "EHLO szxga03-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750800AbaBZD77 (ORCPT ); Tue, 25 Feb 2014 22:59:59 -0500 Sender: kvm-owner@vger.kernel.org List-ID: guest kick vhost base on vring flag status and get perfermance improved, vhost_zerocopy_callback could do this in the same way, as virtqueue_enable_cb need one more check after change the status of avail_ring flags, vhost also do the same thing after vhost_enable_notify test result list as below: guest and host: suse11sp3, netperf, intel 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 | 12 ++++++++++-- 1 files changed, 10 insertions(+), 2 deletions(-) diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c index a0fa5de..3c76b89 100644 --- a/drivers/vhost/net.c +++ b/drivers/vhost/net.c @@ -314,7 +314,8 @@ static void vhost_zerocopy_callback(struct ubuf_info *ubuf, bool success) vq->heads[ubuf->desc].len = 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 */ + smp_wmb(); /* * Trigger polling thread if guest stopped submitting new buffers: * in this case, the refcount after decrement will eventually reach 1. @@ -322,7 +323,8 @@ 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 +388,12 @@ 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) { -- 1.7.3.1.msysgit.0