Re: [PATCH] sched/fair: fix condition of avg_load calculation

[Vincent Guittot]

On Thu, 19 Mar 2020 at 04:36, Tao Zhou <ouwen210@xxxxxxxxxxx> wrote:
>
> In update_sg_wakeup_stats(), the comment says:
>
> Computing avg_load makes sense only when group is fully
> busy or overloaded.
>
> But, the code below this comment does not check like this.
>
> From reading the code about avg_load in other functions, I
> confirm that avg_load should be calculated in fully busy or
> overloaded case. The comment is correct and the checking
> condition is wrong. So, change that condition.
>
> Fixes: 57abff067a08 ("sched/fair: Rework find_idlest_group()")
> Signed-off-by: Tao Zhou <ouwen210@xxxxxxxxxxx>

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

Thanks

> ---
>  kernel/sched/fair.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
> index 1dea8554ead0..9cae03676b0d 100644
> --- a/kernel/sched/fair.c
> +++ b/kernel/sched/fair.c
> @@ -8613,7 +8613,8 @@ static inline void update_sg_wakeup_stats(struct sched_domain *sd,
>          * Computing avg_load makes sense only when group is fully busy or
>          * overloaded
>          */
> -       if (sgs->group_type < group_fully_busy)
> +       if (sgs->group_type == group_fully_busy ||
> +               sgs->group_type == group_overloaded)
>                 sgs->avg_load = (sgs->group_load * SCHED_CAPACITY_SCALE) /
>                                 sgs->group_capacity;
>  }
> --
> 2.24.1