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SubjectRe: [PATCH] ipmi: use round_jiffies on timers to reduce timer overhead/wakeups
On Wed, 21 Oct 2009 10:28:22 -0700
Randy Dunlap <randy.dunlap@oracle.com> wrote:

> From: Randy Dunlap <randy.dunlap@oracle.com>
>
> Use a round_jiffies() variant to reduce overhead of timer
> wakeups. This causes the ipmi timers to occur at the same
> time as other timers (per CPU).
>
> Typical powertop for /ipmi/ (2.6.31, before patch):
> 11.4% (247.4) kipmi0 : __mod_timer (process_timeout)
> 0.6% ( 13.1) <interrupt> : ipmi_si
> 0.5% ( 10.0) <kernel core> : __mod_timer (ipmi_timeout)
>
> powertop for /ipmi/, 2.6.31, after patch:
> 10.8% (247.6) kipmi0 : __mod_timer (process_timeout)
> 0.3% ( 6.9) <interrupt> : ipmi_si
> 0.0% ( 1.0) <kernel core> : __mod_timer (ipmi_timeout)

while it is nice that ipmi_si ande the timer wake up less now.... it's
still rather sad that the 247.6 from kipmi0 are still there..... those
are a much much bigger issue

--
Arjan van de Ven Intel Open Source Technology Centre
For development, discussion and tips for power savings,
visit http://www.lesswatts.org


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