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    SubjectRe: [PATCH] sched: At sched_fork use __set_task_cpu().
    On Wed, Feb 1, 2012 at 7:55 PM, Peter Zijlstra <> wrote:
    > On Tue, 2012-01-31 at 14:18 +0530, Kamalesh Babulal wrote:
    >> * Rakib Mullick <> [2012-01-29 22:34:37]:
    >> >  We don't use select_task_rq() from sched_fork() anymore and no chance of task gets migrated at
    >> > this point. Therefore, we can avoid task migration related checking/accounting, so use
    >> > __set_task_cpu() instead of set_task_cpu().
    >> >
    >> > Signed-off-by: Rakib Mullick <>
    >>   Reviewed-by: Kamalesh Babulal <>
    > Since we call sched_fork() with preemption enabled _long_ after the
    > child is copied from the parent who is to say we (parent) didn't migrate
    > away and are now setting a different cpu?
    If parent gets migrated that should be accounted as parents migration
    count not for child offcourse. And if we're counting child's
    nr_migration count for parent's getting migrated, we're simply
    screwing childs migration count. Isn't it?

    > One could argue that that might not be a real migration from the child's
    > POV, maybe, but nobody seems to be making that argument.
    But I'm not seeing it from child's or parent's POV. I'm simply
    addressing the point of a task's migration counter
    (p->se.nr_migrations), simply this task wasn't moved.

    > I really don't see the point of this..
    I'm hoping, you'll rethink...

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