Re: [PATCH 1/3] sched/fair: Fix statistics for find_idlest_group()

[Vincent Guittot]

Hi Mel,

On Tue, 3 Mar 2020 at 12:03, Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx> wrote:
>
> From: Vincent Guittot <vincent.guittot@xxxxxxxxxx>
>
> From: Vincent Guittot <vincent.guittot@xxxxxxxxxx>
>
> sgs->group_weight is not set while gathering statistics in
> update_sg_wakeup_stats(). This means that a group can be classified as
> fully busy with 0 running tasks if utilization is high enough.
>
> This path is mainly used for fork and exec.
>
> Fixes: 57abff067a08 ("sched/fair: Rework find_idlest_group()")
> Signed-off-by: Vincent Guittot <vincent.guittot@xxxxxxxxxx>
> Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
> Acked-by: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
> Acked-by: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx>
> Signed-off-by: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx>
> Link: https://lore.kernel.org/r/20200218144534.4564-1-vincent.guittot@xxxxxxxxxx

This one has been merged in tip/sched/urgent

> ---
>  kernel/sched/fair.c | 2 ++
>  1 file changed, 2 insertions(+)
>
> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
> index fcc968669aea..4b5d5e5e701e 100644
> --- a/kernel/sched/fair.c
> +++ b/kernel/sched/fair.c
> @@ -8561,6 +8561,8 @@ static inline void update_sg_wakeup_stats(struct sched_domain *sd,
>
>         sgs->group_capacity = group->sgc->capacity;
>
> +       sgs->group_weight = group->group_weight;
> +
>         sgs->group_type = group_classify(sd->imbalance_pct, group, sgs);
>
>         /*
> --
> 2.16.4
>