Re: [RFC PATCH 0/4] timers: framework for migration between CPU

[Balbir Singh <balbir@linux.vnet.ibm.com>]

* 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