From mboxrd@z Thu Jan  1 00:00:00 1970
From: Jeremy Fitzhardinge <jeremy@goop.org>
Subject: Re: [PATCH 09/25] xen: Account for time stolen by Xen
Date: Wed, 25 Apr 2007 11:13:34 -0700
Message-ID: <462F9A4E.5050905@goop.org>
References: <20070423215638.563901986@goop.org> <20070423215710.867690403@goop.org> <200704251115.49966.ak@suse.de>
Mime-Version: 1.0
Content-Type: text/plain; charset=ISO-8859-15
Content-Transfer-Encoding: 7bit
Return-path: <linux-kernel-owner+glk-linux-kernel-3=40m.gmane.org-S1161864AbXDYSNK@vger.kernel.org>
In-Reply-To: <200704251115.49966.ak@suse.de>
Sender: linux-kernel-owner@vger.kernel.org
To: Andi Kleen <ak@suse.de>
Cc: Andrew Morton <akpm@linux-foundation.org>, virtualization@lists.osdl.org, lkml <linux-kernel@vger.kernel.org>, john stultz <johnstul@us.ibm.com>, Keir Fraser <Keir.Fraser@cl.cam.ac.uk>
List-Id: virtualization@lists.linuxfoundation.org

Andi Kleen wrote:
>> +
>> +	do {
>> +		state_time = state->state_entry_time;
>> +		barrier();
>>     
>
> Should be likely rmb

We discussed this, and decided that it wasn't necessary.  The state is
always updated by the current CPU, so if it changes under our feet it
will be because we were preempted, and so that should shoot down any
speculated reads.

    J