From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751734Ab2DPHQn (ORCPT ); Mon, 16 Apr 2012 03:16:43 -0400 Received: from mx1.redhat.com ([209.132.183.28]:9198 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751163Ab2DPHQl (ORCPT ); Mon, 16 Apr 2012 03:16:41 -0400 Date: Mon, 16 Apr 2012 10:16:47 +0300 From: "Michael S. Tsirkin" To: Jason Wang Cc: netdev@vger.kernel.org, xma@us.ibm.com, davem@davemloft.net, linux-kernel@vger.kernel.org, ebiederm@xmission.com Subject: Re: [PATCH 6/6] vhost_net: don't poll on -EFAULT Message-ID: <20120416071646.GB25396@redhat.com> References: <20120416060749.14140.19433.stgit@intel-e5620-16-2.englab.nay.redhat.com> <20120416060833.14140.28139.stgit@intel-e5620-16-2.englab.nay.redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20120416060833.14140.28139.stgit@intel-e5620-16-2.englab.nay.redhat.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Apr 16, 2012 at 02:08:33PM +0800, Jason Wang wrote: > Currently, we restart tx polling unconditionally when sendmsg() > fails. This would cause unnecessary wakeups of vhost wokers as it's > only needed when the socket send buffer were exceeded. Why is this a problem? > Fix this by > restart the tx polling only when sendmsg() returns value other than > -EFAULT. > > Signed-off-by: Jason Wang > --- > drivers/vhost/net.c | 3 ++- > 1 files changed, 2 insertions(+), 1 deletions(-) > > diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c > index 29abd65..035fa95 100644 > --- a/drivers/vhost/net.c > +++ b/drivers/vhost/net.c > @@ -262,7 +262,8 @@ static void handle_tx(struct vhost_net *net) > UIO_MAXIOV; > } > vhost_discard_vq_desc(vq, 1); > - tx_poll_start(net, sock); > + if (err != -EFAULT) > + tx_poll_start(net, sock); > break; > } > if (err != len)