Re: [RFC PATCH v3 3/5] sched: nominate preferred wakeup cpu

[Peter Zijlstra <a.p.zijlstra@chello.nl>]

On Tue, 2008-11-11 at 00:03 +0530, Vaidyanathan Srinivasan wrote:
> When the system utilisation is low and more cpus are idle,
> then the process waking up from sleep should prefer to
> wakeup an idle cpu from semi-idle cpu package (multi core
> package) rather than a completely idle cpu package which
> would waste power.
> 
> Use the sched_mc balance logic in find_busiest_group() to
> nominate a preferred wakeup cpu.
> 
> This info can be sored in appropriate sched_domain, but
> updating this info in all copies of sched_domain is not
> practical.  For now lets try with a per-cpu variable
> pointing to a common storage in partition sched domain
> attribute.  Global variable may not work in partitioned
> sched domain case.

Would it make sense to place the preferred_wakeup_cpu stuff in the
root_domain structure we already have?