linux-kernel - Re: 50 Watt idle power regression bisected to Linux-3.10

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Date:	Thu, 12 Dec 2013 06:37:21 +0100
From:	Mike Galbraith <bitbucket@...ine.de>
To:	"H. Peter Anvin" <hpa@...or.com>
Cc:	Borislav Petkov <bp@...en8.de>, Ingo Molnar <mingo@...nel.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Len Brown <lenb@...nel.org>,
	Linux PM list <linux-pm@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Jeremy Eder <jeder@...hat.com>, x86@...nel.org
Subject: Re: 50 Watt idle power regression bisected to Linux-3.10

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.

With that fixed, it boots, but is not quite perfect.

... 
[  258.560079] fbcon: radeondrmfb (fb0) is primary device
[  258.722483] Console: switching to colour frame buffer device 128x48
[  258.847076] radeon 0000:01:03.0: fb0: radeondrmfb frame buffer device
[  258.911991] radeon 0000:01:03.0: registered panic notifier
[  258.968772] [drm] Initialized radeon 2.35.0 20080528 for 0000:01:03.0 on minor 0
...
[  469.738604] netxen_nic 0000:04:00.3: using msi-x interrupts
[  469.739078] netxen_nic 0000:04:00.3: eth5: GbE port initialized
[  469.830512] ipmi_si 00:01: Found new BMC (man_id: 0x00000b, prod_id: 0x2000, dev_id: 0x13)
[  469.830524] ipmi_si 00:01: IPMI kcs interface initialized
[  473.729862] iTCO_wdt: unable to reset NO_REBOOT flag, device disabled by hardware/BIOS
...
[  711.636741] fuse init (API version 7.22)

...zzzz ok box, doctor appointment is in an hour away.

-Mike 


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