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    SubjectRe: [PATCH 07/16] sched: Make SD_BALANCE_WAKE a topology flag
    On Mon, May 23, 2016 at 11:58:49AM +0100, Morten Rasmussen wrote:
    > For systems with the SD_ASYM_CPUCAPACITY flag set on higher level in the
    > sched_domain hierarchy we need a way to enable wake-up balancing for the
    > lower levels as well as we may want to balance tasks that don't fit the
    > capacity of the previous cpu.
    >
    > We have the option of introducing a new topology flag to express this
    > requirement, or let the existing SD_BALANCE_WAKE flag be set by the
    > architecture as a topology flag. The former means introducing yet
    > another flag, the latter breaks the current meaning of topology flags.
    > None of the options are really desirable.

    I'd propose to replace SD_WAKE_AFFINE with SD_BALANCE_WAKE. And the
    SD_WAKE_AFFINE semantic is simply "waker allowed":

    waker_allowed = cpumask_test_cpu(cpu, tsk_cpus_allowed(p));

    This can be implemented without current functionality change.

    From there, the choice between waker and wakee, and fast path
    select_idle_sibling() and the rest slow path should be reworked, which
    I am thinking about.

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