From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <linux-kernel-owner@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
	id S1754866Ab0GZPrg (ORCPT <rfc822;w@1wt.eu>);
	Mon, 26 Jul 2010 11:47:36 -0400
Received: from hera.kernel.org ([140.211.167.34]:36165 "EHLO hera.kernel.org"
	rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP
	id S1754461Ab0GZPre (ORCPT <rfc822;linux-kernel@vger.kernel.org>);
	Mon, 26 Jul 2010 11:47:34 -0400
Message-ID: <4C4DADD6.90507@kernel.org>
Date: Mon, 26 Jul 2010 17:46:30 +0200
From: Tejun Heo <tj@kernel.org>
User-Agent: Mozilla/5.0 (X11; U; Linux i686 (x86_64); en-US; rv:1.9.2.4) Gecko/20100608 Thunderbird/3.1
MIME-Version: 1.0
To: "Michael S. Tsirkin" <mst@redhat.com>
CC: Oleg Nesterov <oleg@redhat.com>, Sridhar Samudrala <sri@us.ibm.com>,
        netdev <netdev@vger.kernel.org>, lkml <linux-kernel@vger.kernel.org>,
        "kvm@vger.kernel.org" <kvm@vger.kernel.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Dmitri Vorobiev <dmitri.vorobiev@movial.com>,
        Jiri Kosina <jkosina@suse.cz>, Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@elte.hu>, Andi Kleen <ak@linux.intel.com>
Subject: Re: [PATCH UPDATED 1/3] vhost: replace vhost_workqueue with per-vhost
 kthread
References: <4C02C961.9050606@kernel.org> <20100531152221.GB2987@redhat.com> <4C03D983.9010905@kernel.org> <20100531160020.GC3067@redhat.com> <4C04D41B.4050704@kernel.org> <4C06A580.9060300@kernel.org> <20100722155840.GA1743@redhat.com> <4C48B664.9000109@kernel.org> <20100724191447.GA4972@redhat.com> <4C4BEAA2.6040301@kernel.org> <20100726152510.GA26223@redhat.com> <4C4DAB14.5050809@kernel.org>
In-Reply-To: <4C4DAB14.5050809@kernel.org>
X-Enigmail-Version: 1.1.1
Content-Type: text/plain; charset=ISO-8859-1
Content-Transfer-Encoding: 7bit
X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.2.3 (hera.kernel.org [127.0.0.1]); Mon, 26 Jul 2010 15:46:32 +0000 (UTC)
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

On 07/26/2010 05:34 PM, Tejun Heo wrote:
> Hello,
> 
> On 07/26/2010 05:25 PM, Michael S. Tsirkin wrote:
>> BTW, kthread_worker would benefit from the optimization I implemented
>> here as well.
> 
> Hmmm... I'm not quite sure whether it's an optimization.  I thought
> the patch was due to feeling uncomfortable about using barriers?  Is
> it an optimization?

Yeah, one less smp_mb() in execution path.  The lock dancing in
flush() is ugly but then again mucking with barriers could be harder
to understand.  Care to send a patch against wq#for-next tree?

Thanks.

-- 
tejun