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Date: Wed, 11 Dec 2013 17:44:42 +0100
From: Peter Zijlstra <peterz@infradead.org>
To: Ingo Molnar <mingo@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>, Mike Galbraith <bitbucket@online.de>,
        Borislav Petkov <bp@alien8.de>, Len Brown <lenb@kernel.org>,
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        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Jeremy Eder <jeder@redhat.com>, x86@kernel.org
Subject: Re: 50 Watt idle power regression bisected to Linux-3.10
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On Wed, Dec 11, 2013 at 04:09:11PM +0100, Ingo Molnar wrote:
> 
> * Thomas Gleixner <tglx@linutronix.de> wrote:
> 
> > On Wed, 11 Dec 2013, Ingo Molnar wrote:
> > > 
> > > Another thing that is required I think is to issue a write barrier 
> > > before CLFLUSH instruction. By my (possibly incorrect ...) reading of 
> > > the documentation CLFLUSH does not appear to be ordered (at all), so 
> > > it might execute before the modification to the affected memory?
> > 
> > We already have a write barrier in the code which modifies
> > current_thread_info()->flags.
> 
> Which code is that, could you please cite it? (I tried finding it but 
> my grep-fu failed me.)

current_set_polling_and_test().