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Date: Thu, 19 Dec 2013 18:36:29 +0100
From: Peter Zijlstra <peterz@infradead.org>
To: Ingo Molnar <mingo@kernel.org>
Cc: "H. Peter Anvin" <hpa@zytor.com>, Len Brown <lenb@kernel.org>,
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        Thomas Gleixner <tglx@linutronix.de>, Mike Galbraith <efault@gmx.de>,
        Borislav Petkov <bp@alien8.de>
Subject: Re: [PATCH] x86 idle: repair large-server 50-watt idle-power
 regression
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On Thu, Dec 19, 2013 at 06:25:35PM +0100, Peter Zijlstra wrote:
> That said, I would find it very strange indeed if a CLFLUSH doesn't also
> flush the store buffer.

OK, it explicitly states it does not do that and you indeed need an
mfence before the clflush.