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Re: [PATCH v2 3/5] sched/fair: Fix find_idlest_group when local group is not allowed

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On 25 August 2017 at 12:16, Brendan Jackman <brendan.jackman@arm.com> wrote:
> When the local group is not allowed we do not modify this_*_load from
> their initial value of 0. That means that the load checks at the end
> of find_idlest_group cause us to incorrectly return NULL. Fixing the
> initial values to ULONG_MAX means we will instead return the idlest
> remote group in that case.
>
> Signed-off-by: Brendan Jackman <brendan.jackman@arm.com>
> Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
> Cc: Vincent Guittot <vincent.guittot@linaro.org>
> Cc: Josef Bacik <josef@toxicpanda.com>
> Cc: Ingo Molnar <mingo@redhat.com>
> Cc: Morten Rasmussen <morten.rasmussen@arm.com>
> Cc: Peter Zijlstra <peterz@infradead.org>

Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org>

> ---
>  kernel/sched/fair.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
> index 4ccecbf825bf..0ce75bbcde45 100644
> --- a/kernel/sched/fair.c
> +++ b/kernel/sched/fair.c
> @@ -5387,8 +5387,9 @@ find_idlest_group(struct sched_domain *sd, struct task_struct *p,
>  {
>         struct sched_group *idlest = NULL, *group = sd->groups;
>         struct sched_group *most_spare_sg = NULL;
> -       unsigned long min_runnable_load = ULONG_MAX, this_runnable_load = 0;
> -       unsigned long min_avg_load = ULONG_MAX, this_avg_load = 0;
> +       unsigned long min_runnable_load = ULONG_MAX;
> +       unsigned long this_runnable_load = ULONG_MAX;
> +       unsigned long min_avg_load = ULONG_MAX, this_avg_load = ULONG_MAX;
>         unsigned long most_spare = 0, this_spare = 0;
>         int load_idx = sd->forkexec_idx;
>         int imbalance_scale = 100 + (sd->imbalance_pct-100)/2;
> --
> 2.14.1
>

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[PATCH v2 0/5] sched/fair: Tweaks for select_task_rq_fair slowpath Brendan Jackman <brendan.jackman@arm.com> - 2017-08-25 12:20 +0200
  [PATCH v2 1/5] sched/fair: Move select_task_rq_fair slow-path into its own function Brendan Jackman <brendan.jackman@arm.com> - 2017-08-25 12:20 +0200
    Re: [PATCH v2 1/5] sched/fair: Move select_task_rq_fair slow-path  into its own function Josef Bacik <josef@toxicpanda.com> - 2017-08-25 14:30 +0200
    Re: [PATCH v2 1/5] sched/fair: Move select_task_rq_fair slow-path  into its own function Vincent Guittot <vincent.guittot@linaro.org> - 2017-08-25 15:50 +0200
  [PATCH v2 5/5] sched/fair: Fix use of find_idlest_group when local group is idlest. Brendan Jackman <brendan.jackman@arm.com> - 2017-08-25 12:20 +0200
    Re: [PATCH v2 5/5] sched/fair: Fix use of find_idlest_group when  local group is idlest. Vincent Guittot <vincent.guittot@linaro.org> - 2017-08-25 15:40 +0200
      Re: [PATCH v2 5/5] sched/fair: Fix use of find_idlest_group when local group is idlest. Brendan Jackman <brendan.jackman@arm.com> - 2017-08-25 18:00 +0200
        Re: [PATCH v2 5/5] sched/fair: Fix use of find_idlest_group when  local group is idlest. Vincent Guittot <vincent.guittot@linaro.org> - 2017-08-28 11:00 +0200
          Re: [PATCH v2 5/5] sched/fair: Fix use of find_idlest_group when  local group is idlest. Vincent Guittot <vincent.guittot@linaro.org> - 2017-08-28 11:20 +0200
          Re: [PATCH v2 5/5] sched/fair: Fix use of find_idlest_group when local group is idlest. Brendan Jackman <brendan.jackman@arm.com> - 2017-08-29 19:20 +0200
  [PATCH v2 4/5] sched/fair: Fix use of find_idlest_group when no groups are allowed Brendan Jackman <brendan.jackman@arm.com> - 2017-08-25 12:20 +0200
    Re: [PATCH v2 4/5] sched/fair: Fix use of find_idlest_group when no  groups are allowed Vincent Guittot <vincent.guittot@linaro.org> - 2017-08-25 15:40 +0200
  [PATCH v2 3/5] sched/fair: Fix find_idlest_group when local group is not allowed Brendan Jackman <brendan.jackman@arm.com> - 2017-08-25 12:20 +0200
    Re: [PATCH v2 3/5] sched/fair: Fix find_idlest_group when local group  is not allowed Vincent Guittot <vincent.guittot@linaro.org> - 2017-08-25 15:50 +0200
  [PATCH v2 2/5] sched/fair: Remove unnecessary comparison with -1 Brendan Jackman <brendan.jackman@arm.com> - 2017-08-25 12:20 +0200
    Re: [PATCH v2 2/5] sched/fair: Remove unnecessary comparison with -1 Josef Bacik <josef@toxicpanda.com> - 2017-08-25 14:50 +0200
    Re: [PATCH v2 2/5] sched/fair: Remove unnecessary comparison with -1 Vincent Guittot <vincent.guittot@linaro.org> - 2017-08-25 15:50 +0200

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