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    SubjectRe: [PATCH V2 Resend 0/4] Create sched_select_cpu() and use it for workqueues and timers
    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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