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Message-ID: <1386824397.6056.21.camel@marge.simpson.net>
Subject: Re: 50 Watt idle power regression bisected to Linux-3.10
From: Mike Galbraith <bitbucket@online.de>
To: "H. Peter Anvin" <hpa@zytor.com>
Cc: Borislav Petkov <bp@alien8.de>, Ingo Molnar <mingo@kernel.org>,
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        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
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Date: Thu, 12 Dec 2013 05:59:57 +0100
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On Wed, 2013-12-11 at 20:49 -0800, H. Peter Anvin wrote: 
> On 12/11/2013 08:25 PM, Mike Galbraith wrote:
> >  arch/x86/include/asm/mwait.h   |    4 ++--
> >  arch/x86/kernel/cpu/common.c   |    7 ++++---
> >  arch/x86/kernel/setup_percpu.c |    1 +
> >  3 files changed, 7 insertions(+), 5 deletions(-)
> > 
> > Index: linux-2.6/arch/x86/kernel/cpu/common.c
> > ===================================================================
> > --- linux-2.6.orig/arch/x86/kernel/cpu/common.c
> > +++ linux-2.6/arch/x86/kernel/cpu/common.c
> > @@ -65,13 +65,14 @@ void __init setup_cpu_local_masks(void)
> >  }
> >  
> >  /* allocate percpu area for mwait doorbell */
> > -char __percpu *mwait_doorbell;
> > +DEFINE_PER_CPU(char *, mwait_doorbell);
> > +EXPORT_PER_CPU_SYMBOL(mwait_doorbell);
> >  
> 
> Sorry, this is wrong.  This is NOT a percpu variable, it is a pointer to
> a percpu allocation, but the variable itself is not a percpu variable.
> This explains your boom.

Yeah, I know, I already slapped myself upside the head.

(what were you thinking mikie...la la la la la:)

-Mike