From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756051AbdC2MIl (ORCPT ); Wed, 29 Mar 2017 08:08:41 -0400 Received: from mx1.redhat.com ([209.132.183.28]:57688 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755963AbdC2MHN (ORCPT ); Wed, 29 Mar 2017 08:07:13 -0400 DMARC-Filter: OpenDMARC Filter v1.3.2 mx1.redhat.com 088428FCE5 Authentication-Results: ext-mx02.extmail.prod.ext.phx2.redhat.com; dmarc=none (p=none dis=none) header.from=redhat.com Authentication-Results: ext-mx02.extmail.prod.ext.phx2.redhat.com; spf=pass smtp.mailfrom=mst@redhat.com DKIM-Filter: OpenDKIM Filter v2.11.0 mx1.redhat.com 088428FCE5 Date: Wed, 29 Mar 2017 15:07:10 +0300 From: "Michael S. Tsirkin" To: Jason Wang Cc: kvm@vger.kernel.org, virtualization@lists.linux-foundation.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH net-next 8/8] vhost_net: use lockless peeking for skb array during busy polling Message-ID: <20170329150538-mutt-send-email-mst@kernel.org> References: <1490069087-4783-1-git-send-email-jasowang@redhat.com> <1490069087-4783-9-git-send-email-jasowang@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1490069087-4783-9-git-send-email-jasowang@redhat.com> X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.26]); Wed, 29 Mar 2017 12:07:12 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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. > @@ -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 From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Michael S. Tsirkin" Subject: Re: [PATCH net-next 8/8] vhost_net: use lockless peeking for skb array during busy polling Date: Wed, 29 Mar 2017 15:07:10 +0300 Message-ID: <20170329150538-mutt-send-email-mst@kernel.org> References: <1490069087-4783-1-git-send-email-jasowang@redhat.com> <1490069087-4783-9-git-send-email-jasowang@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org, kvm@vger.kernel.org, virtualization@lists.linux-foundation.org To: Jason Wang Return-path: Content-Disposition: inline In-Reply-To: <1490069087-4783-9-git-send-email-jasowang@redhat.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: virtualization-bounces@lists.linux-foundation.org Errors-To: virtualization-bounces@lists.linux-foundation.org List-Id: netdev.vger.kernel.org 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. > @@ -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