From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754217Ab3FELGw (ORCPT ); Wed, 5 Jun 2013 07:06:52 -0400 Received: from mx1.redhat.com ([209.132.183.28]:29652 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752978Ab3FELGu (ORCPT ); Wed, 5 Jun 2013 07:06:50 -0400 Date: Wed, 5 Jun 2013 14:07:22 +0300 From: "Michael S. Tsirkin" To: Jason Wang Cc: davem@davemloft.net, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, sergei.shtylyov@cogentembedded.com Subject: Re: [net-next rfc V3 2/9] macvtap: do not add self to waitqueue if doing a nonblock read Message-ID: <20130605110722.GK31830@redhat.com> References: <1370414192-5830-1-git-send-email-jasowang@redhat.com> <1370414192-5830-3-git-send-email-jasowang@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1370414192-5830-3-git-send-email-jasowang@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Jun 05, 2013 at 02:36:25PM +0800, Jason Wang wrote: > There's no need to add self to waitqueue if doing a nonblock read. This could > help to avoid the spinlock contention. > > Signed-off-by: Jason Wang Acked-by: Michael S. Tsirkin > --- > drivers/net/macvtap.c | 7 +++++-- > 1 files changed, 5 insertions(+), 2 deletions(-) > > diff --git a/drivers/net/macvtap.c b/drivers/net/macvtap.c > index 5e485e3..8949631 100644 > --- a/drivers/net/macvtap.c > +++ b/drivers/net/macvtap.c > @@ -845,7 +845,9 @@ static ssize_t macvtap_do_read(struct macvtap_queue *q, struct kiocb *iocb, > ssize_t ret = 0; > > while (len) { > - prepare_to_wait(sk_sleep(&q->sk), &wait, TASK_INTERRUPTIBLE); > + if (!noblock) > + prepare_to_wait(sk_sleep(&q->sk), &wait, > + TASK_INTERRUPTIBLE); > > /* Read frames from the queue */ > skb = skb_dequeue(&q->sk.sk_receive_queue); > @@ -867,7 +869,8 @@ static ssize_t macvtap_do_read(struct macvtap_queue *q, struct kiocb *iocb, > break; > } > > - finish_wait(sk_sleep(&q->sk), &wait); > + if (!noblock) > + finish_wait(sk_sleep(&q->sk), &wait); > return ret; > } > > -- > 1.7.1