Messages in this thread | | | Date | Mon, 26 Nov 2012 11:03:54 -0800 | From | "Paul E. McKenney" <> | Subject | Re: [PATCH V2 Resend 0/4] Create sched_select_cpu() and use it for workqueues and timers |
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On Mon, Nov 26, 2012 at 12:35:52PM -0500, Steven Rostedt wrote: > On Mon, 2012-11-26 at 09:03 -0800, Paul E. McKenney wrote: > > > > If I understand correctly (though also suffering turkey OD), the idea is > > to offload work to more energy-efficient CPUs. > > This is determined by a CPU that isn't running the idle task? Is it > because a CPU that just woke up may be running at a lower freq, and thus > not as efficient? But pushing off to another CPU may cause cache misses > as well. Wouldn't that also be a factor in efficiencies, if a CPU is > stalled waiting for memory to be loaded?
Two different microarchitectures -- same instruction set (at user level, anyway), but different power/performance characteristics. One set is optimized for performance, the other for energy efficiency. For example, ARM's big.LITTLE architecture.
> I should also ask the obvious. Has these patches shown real world > efficiencies or is this just a theory? Do these patches actually improve > battery life when applied?
I must defer to Viresh on this one.
Thanx, Paul
> Just asking. > > -- Steve > >
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