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    SubjectRe: [PATCH RESEND v9 00/10] sched: consolidation of CPU capacity and usage
    On 20 February 2015 at 12:52, Morten Rasmussen <morten.rasmussen@arm.com> wrote:
    > On Fri, Feb 20, 2015 at 11:34:47AM +0000, Peter Zijlstra wrote:
    >> On Thu, Feb 19, 2015 at 12:49:40PM +0000, Morten Rasmussen wrote:
    >>
    >> > Also, it still not clear why patch 10 uses relative capacity reduction
    >> > instead of absolute capacity available to CFS tasks.
    >>
    >> As present in your asymmetric big and small systems? Yes it would be
    >> unfortunate to migrate a task to an idle small core when the big core is
    >> still faster, even if reduced by rt/irq work.
    >
    > Yes, exactly. I don't think it would cause any harm for symmetric cases
    > to use absolute capacity instead. Am I missing something?

    If absolute capacity is used, we will trig an active load balance from
    little to big core each time a little has got 1 task and a big core is
    idle whereas we only want to trig an active migration is the src_cpu's
    capacity that is available for the cfs task is significantly reduced
    by rt tasks.

    I can mix absolute and relative tests by 1st testing that the capacity
    of the src is reduced and then ensure that the dst_cpu has more
    absolute capacity than src_cpu


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