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    SubjectRe: [RESEND RFC PATCH V3] sched: Improve scalability of select_idle_sibling using SMT balance
    On Fri, Feb 02, 2018 at 11:53:40AM -0500, Steven Sistare wrote:
    > It might be interesting to add a tunable for the number of random choices to
    > make, and clamp it at the max nr computed from avg_cost in select_idle_cpu.

    This needs a fairly complicated PRNG for it would need to visit each
    possible CPU once before looping. A LFSR does that, but requires 2^n-1
    elements and we have topology masks that don't match that.. The trivial
    example is something with 6 cores.

    > Or, choose a random starting point and then search for nr sequential
    > candidates; possibly limited by a tunable.

    And this is basically what we already do. Except with the task-cpu
    instead of a per-cpu rotor.

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