On Tue, Mar 25, 2008 at 7:49 PM, Arjan van de Ven <[EMAIL PROTECTED]> wrote:
> Colin Ian King wrote:
>  > Hi,
>  >
>  > I've noticed that there a quite a few users reporting excessive amounts
>  > of "Rescheduling Interrupts" from multi core machines, and it seems
>  > concerting that the scheduler is pulling the processors out of C3 states
>  > rather a lot. In some cases, there are reports of >10,000 Rescheduling
>  > Interrupts a second, which seems excessive.
>  >
>  > The following rune apparently should help, but it does not make (much)
>  > of a significant change:
>  >
>  >   echo 1 > /sys/devices/system/cpu/sched_mc_power_savings
>
>  this only does something on multi-socket systems, not on dual core single 
> socket systems.
>
>

I suspect the mc in the name can be confused for Multi-Core, what does
mc stand for?

>  >
>  > Since it may be draining excessive amounts of power are there ideas if
>  > this a scheduling problem and how to resolve this?
>  > Thanks,
>
>
>  it's a combination of two things:
>  1) An application or interrupt IS waking things up at that frequency.
>     It's currently hard to track down which one; it may need kernel changes
>     to be able to find out.
>  2) The scheduler lately seems very trigger happy to do a remote wakeup 
> rather than
>     local wakeups for the wakups done by 1)

I would be suspicious of wake_idle(). Gautham has been looking at the
wake_idle() code and its impact on power savings.

Balbir

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