From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754340Ab0BGJsF (ORCPT ); Sun, 7 Feb 2010 04:48:05 -0500 Received: from mx1.redhat.com ([209.132.183.28]:28026 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753713Ab0BGJsC (ORCPT ); Sun, 7 Feb 2010 04:48:02 -0500 Date: Sun, 7 Feb 2010 11:44:42 +0200 From: "Michael S. Tsirkin" To: Avi Kivity Cc: Rusty Russell , kvm@vger.kernel.org, virtualization@lists.osdl.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, David Miller Subject: Re: [PATCH] vhost-net: switch to smp barriers Message-ID: <20100207094441.GA20271@redhat.com> References: <20100201172101.GA10900@redhat.com> <4B6E8B05.8070607@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4B6E8B05.8070607@redhat.com> User-Agent: Mutt/1.5.19 (2009-01-05) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, Feb 07, 2010 at 11:42:29AM +0200, Avi Kivity wrote: > On 02/01/2010 07:21 PM, Michael S. Tsirkin wrote: >> vhost-net only uses memory barriers to control SMP effects >> (communication with userspace potentially running on a different CPU), >> so it should use SMP barriers and not mandatory barriers for memory >> access ordering, as suggested by Documentation/memory-barriers.txt >> >> > > A UP guest running on an SMP host still needs those barriers. Correct. And since vhost net is running host-side, smp_XX barriers will do exactly the right thing, right? > -- > error compiling committee.c: too many arguments to function