linux-kernel - RE: 100% C0 with 2.6.25-rc

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Message-ID: <924EFEDD5F540B4284297C4DC59F3DEE9A9620@orsmsx423.amr.corp.intel.com>
Date:	Fri, 22 Feb 2008 09:03:55 -0800
From:	"Pallipadi, Venkatesh" <venkatesh.pallipadi@...el.com>
To:	"Jan Willies" <jan@...lies.info>, "Rafael J. Wysocki" <rjw@...k.pl>
Cc:	<linux-acpi@...r.kernel.org>, "Ingo Molnar" <mingo@...e.hu>,
	"LKML" <linux-kernel@...r.kernel.org>,
	"Thomas Gleixner" <tglx@...utronix.de>
Subject: RE: 100% C0 with 2.6.25-rc

 

>-----Original Message-----
>From: Jan Willies [mailto:jan@...lies.info] 
>Sent: Friday, February 22, 2008 7:56 AM
>To: Rafael J. Wysocki
>Cc: linux-acpi@...r.kernel.org; Ingo Molnar; LKML; Thomas 
>Gleixner; Pallipadi, Venkatesh
>Subject: Re: 100% C0 with 2.6.25-rc
>
>Rafael J. Wysocki wrote:
>> On Thursday, 21 of February 2008, Jan Willies wrote:
>>> Since 2.6.25-rc1 I have a lot of wakeups/s (≈134191,4) and 
>spend 100% in C0.
>>> It worked fine with 2.6.24 and commandline nolapic. Without 
>nolapic I had 80k
>>> wakeups/s after some time, but not right from the start like now.  
>> 
>> We have a regression from 2.6.24, apparently interrupts-related.
>
>After a lot of bisecting I've found the bad commit: 
>
>9b12e18cdc1553de62d931e73443c806347cd974 is first bad commit
>commit 9b12e18cdc1553de62d931e73443c806347cd974
>Author: venkatesh.pallipadi@...el.com <venkatesh.pallipadi@...el.com>
>Date:   Thu Jan 31 17:35:05 2008 -0800
>
>    ACPI: cpuidle: Support C1 idle time accounting
>    
>    Show C1 idle time in /sysfs cpuidle interface. C1 idle time may not
>    be entirely accurate in all cases. It includes the time spent
>    in the interrupt handler after wakeup with "hlt" based C1. 
>But, it will
>    be accurate with "mwait" based C1.
>
>
>Reverting the commit brings my laptop back to C2.
>

Thanks for the bisect info. I will look at the bad side effects that patch may be having and I should have a patch for you to test later today....

Thanks,
Venki
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