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    Subject[PATCH 01/10] sched/fair: Update affine statistics when needed
    Date
    wake_affine_idle() can return prev_cpu. Even in such a scenario,
    scheduler was going ahead and updating schedstats related to wake
    affine. i.e even if the task is not moved across LLC domains,
    schedstats would have accounted.

    Hence add a check before updating schedstats.

    Cc: LKML <linux-kernel@vger.kernel.org>
    Cc: Gautham R Shenoy <ego@linux.vnet.ibm.com>
    Cc: Parth Shah <parth@linux.ibm.com>
    Cc: Ingo Molnar <mingo@kernel.org>
    Cc: Peter Zijlstra <peterz@infradead.org>
    Cc: Valentin Schneider <valentin.schneider@arm.com>
    Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
    Cc: Mel Gorman <mgorman@techsingularity.net>
    Cc: Vincent Guittot <vincent.guittot@linaro.org>
    Cc: Rik van Riel <riel@surriel.com>
    Signed-off-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
    ---
    kernel/sched/fair.c | 6 ++++--
    1 file changed, 4 insertions(+), 2 deletions(-)

    diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
    index 794c2cb945f8..a258a84cfdfd 100644
    --- a/kernel/sched/fair.c
    +++ b/kernel/sched/fair.c
    @@ -5884,8 +5884,10 @@ static int wake_affine(struct sched_domain *sd, struct task_struct *p,
    if (target == nr_cpumask_bits)
    return prev_cpu;

    - schedstat_inc(sd->ttwu_move_affine);
    - schedstat_inc(p->se.statistics.nr_wakeups_affine);
    + if (!cpus_share_cache(prev_cpu, target)) {
    + schedstat_inc(sd->ttwu_move_affine);
    + schedstat_inc(p->se.statistics.nr_wakeups_affine);
    + }
    return target;
    }

    --
    2.18.2
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