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    SubjectRe: [PATCH] sched/core: add forced idle accounting for cgroups
    On Fri, May 20, 2022 at 11:43 AM Tejun Heo <tj@kernel.org> wrote:
    >
    > Hello,
    >
    > Sorry about late reply and thanks for the ping. I missed this one.
    >
    > On Fri, May 13, 2022 at 12:23:16PM -0700, Josh Don wrote:
    > > Yea, that's right, this doesn't require the cpu controller to be
    > > enabled. Are you suggesting to add a new field to cgroup_base_stat?
    >
    > Yes, that's what I meant. I think it'd fit there better.

    Sounds good, I'll send a second version of the patch with that change.

    > > One other weird artifact of collecting forceidle time is that a cpu
    > > may account it on behalf of its hyperthread sibling. Currently, the
    > > core rstat code always accounts to the current cpu's percpu rstat
    > > field. I can add an accounting function to support writes to a
    > > different cpu's field, in order to make sure that the per-cpu totals
    > > are correct (the forceidle accounting code holds rq->__lock, which
    > > protects all HT siblings of a core). percpu totals aren't currently
    > > exported in cgroup v2, but this is useful information that we'll
    > > consume, so it would be nice to keep it accurate.
    >
    > Sure, as long as it doesn't incur overhead when not used.

    The extra complexity actually doesn't seem to be required. Per-core
    totals will be accurate, which is the important part.

    Thanks,
    Josh

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