Re: Rescheduling interrupts

[Ingo Molnar <mingo@elte.hu>]

* Matt Mackall <mpm@selenic.com> wrote:

> > amarokapp does wake up threads every 20 microseconds - that could 
> > explain it. It's probably Xorg running on one core, amarokapp on the 
> > other core. That's already 100 reschedules/sec.
> 
> That suggests we want an "anti-load-balancing" heuristic when CPU 
> usage is very low. Migrating everything onto one core when we're close 
> to idle will save power and probably reduce latencies.

that would probably be the case if it's multiple sockets - but for 
multiple cores exactly the opposite is true: the sooner _both_ cores 
finish processing, the deeper power use the CPU can reach. So effective 
and immediate spreading of workloads amongst multiple cores - especially 
with shared L2 caches where the cost of migration is low, helps power 
consumption. (and it obviously helps latencies and bandwith)

	Ingo