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    SubjectRe: [PATCH v4 1/7] sched/fair: default to false in test_idle_cores
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    Hi Josh, thanks for your comments!

    On 6/28/22 6:53 AM, Josh Don Wrote:
    > On Sun, Jun 19, 2022 at 5:05 AM Abel Wu <wuyun.abel@bytedance.com> wrote:
    >>
    >> It's uncertain whether idle cores exist or not if shared sched-domains
    >> are not ready, so returning "no idle cores" usually makes sense.
    >>
    >> While __update_idle_core() is an exception, it checks status of this
    >> core and set to shared sched-domain if necessary. So the whole logic
    >> depends on the existence of shared domain, and can bail out early if
    >> it isn't available. Modern compilers seems capable of handling such
    >> cases, so remove the tricky self-defined default return value.
    >
    > I don't think the compiler will be able to bail out of the smt
    > iteration early, since it'll have to do another rcu dereference for
    > the sd_llc in set(). But I also don't think this case needs
    > optimization, since it should be transient while the domain isn't
    > ready.
    >
    > Reviewed-by: Josh Don <joshdon@google.com>

    Obviously I failed to comprehend the difference between the changed
    assembly code, my bad..

    Thanks,
    Abel

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