RE: 2.6.25 regression: powertop says 120K wakeups/sec

From: Pallipadi, Venkatesh
Date: Mon Mar 31 2008 - 14:44:20 EST




>-----Original Message-----
>From: Mark Lord [mailto:lkml@xxxxxx]
>Sent: Monday, March 31, 2008 10:43 AM
>To: Rafael J. Wysocki
>Cc: Pallipadi, Venkatesh; David Brownell; Andrew Morton;
>linux-kernel@xxxxxxxxxxxxxxx; linux-acpi@xxxxxxxxxxxxxxx; Len Brown
>Subject: Re: 2.6.25 regression: powertop says 120K wakeups/sec
>
>Rafael J. Wysocki wrote:
>> On Friday, 28 of March 2008, Venki Pallipadi wrote:
>>> On Fri, Mar 28, 2008 at 03:09:22PM -0700, David Brownell wrote:
>>>> On Friday 28 March 2008, Pallipadi, Venkatesh wrote:
>>>>> You should have a dmesg line which looks like
>>>>> ACPI: CPU0 (power states: C1[C1] C2[C2]
>>>>> Do you see C2 in such line?
>>>> Yes:
>>>>
>>>> ACPI: CPU0 (power states: C1[C1] C2[C2])
>>>
>>> David,
>>>
>>> I think I figured out the bug...
>>>
>>> Can you try the below patch and confirm that it works (over
>upstream - ignore
>>> the earlier revert patch I sent to you).
>>>
>>> Thanks,
>>> Venki
>>>
>>> ----
>>>
>>>
>>> Patch to fix huge number of wakeups reported due to recent
>changes in
>>> processor_idle.c. The problem was that the entry_method
>determination was
>>> broken due to one of the recent commits (bc71bec91f987) causing
>>> C1 entry to not to go to halt. This should also fix the
>hang reported here.
>>> http://bugzilla.kernel.org/show_bug.cgi?id=10093
>>
>> Ah, thanks for figuring that out. As a regression fix, it
>should go upstream
>> ASAP, I think.
>..
>
>Would this have any applicability to 2.6.24 as well?
>

No. This patch is for a regression that happened post .24.
pre .24 will be a different problem.

Thanks,
Venki
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