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SubjectRe: [RFC PATCH 0/4] timers: framework for migration between CPU
* Ingo Molnar <mingo@elte.hu> [2009-02-23 12:07:25]:

>
> * Vaidyanathan Srinivasan <svaidy@linux.vnet.ibm.com> wrote:
>
> > My understanding is that we will certainly have a sysfs
> > tunable to 'enable' timer migration or consolidation, similar
> > to the sched_mc=2 policy, but the actual set of CPUs to
> > evacuate and the correct set of target CPUs to consolidate
> > should come from the scheduler and not necessarily from the
> > user space.
>
> Yes.
>
> > The scheduler should be able to figure out the following
> > parameters:
> >
> > * Identify set of idle CPUs (CPU package) from which timers
> > can be removed
> > * Identify a semi-idle or idle CPU package to which the timers
> > can be moved
> > * Decide when to start moving timers as the system has large
> > number of idle CPUs
> > * Decide when to stop migrating as system becomes less idle
> > and utilisation increases
> >
> > Guiding all of the above decisions from user space may not be
> > fast enough.
>
> Exactly.
>

OK, lets head that way for now. I've highlighted my concerns in a
different email. Experimentation will definitely show us if they are
justified or not.
--
Balbir


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