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Date: Wed, 25 Apr 2007 11:13:34 -0700
From: Jeremy Fitzhardinge <jeremy@goop.org>
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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>
Subject: Re: [PATCH 09/25] xen: Account for time stolen by Xen
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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