>-----Original Message-----
>From: Björn Steinbrink [mailto:[email protected]]
>Sent: Monday, May 21, 2007 12:50 AM
>To: Andi Kleen
>Cc: [email protected]; [email protected]; Zhu, Yi;
>[email protected]; [email protected]; Pallipadi,
>Venkatesh; [email protected]
>Subject: Re: Increased ipw2200 power usage with dynticks
>
>On 2007.05.20 20:55:35 +0200, Andi Kleen wrote:
>> Björn Steinbrink <[email protected]> writes:
>> >
>> > Ok, it seems that ipw2200 is just a trigger for the
>problem here. AFAICT
>> > the cause of the worse C state usage is that after ipw2200
>has woken the
>> > cpu, acpi_processor_idle() chooses C2 (due to dma? bm? I have no
>> > idea...) as the prefered sleep state. Now without NO_HZ or
>when I hold
>> > down a key, there are interrupts that wake up the CPU and when
>> > acpi_processor_idle() is called again the promotion to
>C3/C4 happens.
>> > But with NO_HZ, there are no such interrupts, most wakeups
>are caused by
>> > ipw2200 and so the processor doesn't go any deeper than C2
>most of the
>> > time and thus wastes lots of power.
>>
>> The cpuidle governour code Venki is working on is supposed
>to address this.
>> There have been also earlier prototype patches by Adam Belay and
>> Thomas Renninger.
>
>Venki (at least I think it was him) also told me about cpuidle and the
>menu governor on #powertop. Unfortunately, cpuidle seems to be
>gone from
>acpi-test (or I'm simply still too stupid for git/gitweb). I manually
>added the cpuidle and menu governor patches on top of my
>2.6.22-rc1-hrt8
>kernel, but that broke C-state duration accounting.
>
>On the bright side of things is power usage though, which is down to an
>incredible 13.9W in idle+ipw2200 :)
>
Nice to hear that cpuidle-menu governor gets 13.9W :-).
Powertop will need some changes to go with cpuidle, but that should be simple.
We need some more testing for cpuidle before it gets into git.
Len: Looks like cpuidle got dropped out of mm again. Can you merge it back it please.
Thanks,
Venki
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