Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753827AbdC3CQY (ORCPT ); Wed, 29 Mar 2017 22:16:24 -0400 Received: from mx1.redhat.com ([209.132.183.28]:40832 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751394AbdC3CQX (ORCPT ); Wed, 29 Mar 2017 22:16:23 -0400 DMARC-Filter: OpenDMARC Filter v1.3.2 mx1.redhat.com D50A5C04BD5E Authentication-Results: ext-mx07.extmail.prod.ext.phx2.redhat.com; dmarc=none (p=none dis=none) header.from=redhat.com Authentication-Results: ext-mx07.extmail.prod.ext.phx2.redhat.com; spf=pass smtp.mailfrom=jasowang@redhat.com DKIM-Filter: OpenDKIM Filter v2.11.0 mx1.redhat.com D50A5C04BD5E Subject: Re: [PATCH net-next 8/8] vhost_net: use lockless peeking for skb array during busy polling To: "Michael S. Tsirkin" References: <1490069087-4783-1-git-send-email-jasowang@redhat.com> <1490069087-4783-9-git-send-email-jasowang@redhat.com> <20170329150538-mutt-send-email-mst@kernel.org> Cc: kvm@vger.kernel.org, virtualization@lists.linux-foundation.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org From: Jason Wang Message-ID: <104c0c1f-e2fd-f5d0-0aae-c308d1f1373c@redhat.com> Date: Thu, 30 Mar 2017 10:16:15 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.8.0 MIME-Version: 1.0 In-Reply-To: <20170329150538-mutt-send-email-mst@kernel.org> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.31]); Thu, 30 Mar 2017 02:16:22 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1554 Lines: 50 On 2017年03月29日 20:07, Michael S. Tsirkin wrote: > On Tue, Mar 21, 2017 at 12:04:47PM +0800, Jason Wang wrote: >> For the socket that exports its skb array, we can use lockless polling >> to avoid touching spinlock during busy polling. >> >> Signed-off-by: Jason Wang >> --- >> drivers/vhost/net.c | 7 +++++-- >> 1 file changed, 5 insertions(+), 2 deletions(-) >> >> diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c >> index 53f09f2..41153a3 100644 >> --- a/drivers/vhost/net.c >> +++ b/drivers/vhost/net.c >> @@ -551,10 +551,13 @@ static int peek_head_len(struct vhost_net_virtqueue *rvq, struct sock *sk) >> return len; >> } >> >> -static int sk_has_rx_data(struct sock *sk) >> +static int sk_has_rx_data(struct vhost_net_virtqueue *rvq, struct sock *sk) >> { >> struct socket *sock = sk->sk_socket; >> >> + if (rvq->rx_array) >> + return !__skb_array_empty(rvq->rx_array); >> + >> if (sock->ops->peek_len) >> return sock->ops->peek_len(sock); >> > I don't see which patch adds __skb_array_empty. This is not something new, it was introduced by ad69f35d1dc0a ("skb_array: array based FIFO for skbs"). Thanks > >> @@ -579,7 +582,7 @@ static int vhost_net_rx_peek_head_len(struct vhost_net *net, >> endtime = busy_clock() + vq->busyloop_timeout; >> >> while (vhost_can_busy_poll(&net->dev, endtime) && >> - !sk_has_rx_data(sk) && >> + !sk_has_rx_data(rvq, sk) && >> vhost_vq_avail_empty(&net->dev, vq)) >> cpu_relax(); >> >> -- >> 2.7.4