Re: [PATCH v2] sched/fair: Fix cfs_rq_is_decayed() on !SMP

[Vincent Guittot]

On Fri, 18 Aug 2023 at 15:22, <chengming.zhou@xxxxxxxxx> wrote:
>
> From: Chengming Zhou <zhouchengming@xxxxxxxxxxxxx>
>
> We don't need to maintain per-queue leaf_cfs_rq_list on !SMP, since
> it's used for cfs_rq load tracking & balance on SMP.
>
> But sched debug interface use it to print per-cfs_rq stats, which
> maybe better to change to use walk_tg_tree_from() instead.
>
> This patch just fix the !SMP version cfs_rq_is_decayed(), so the
> per-queue leaf_cfs_rq_list is also maintained correctly on !SMP,
> to fix the warning in assert_list_leaf_cfs_rq().
>
> Fixes: 0a00a354644e ("sched/fair: Delete useless condition in tg_unthrottle_up()")
> Reported-by: Leo Liang <ycliang@xxxxxxxxxxxxx>
> Signed-off-by: Chengming Zhou <zhouchengming@xxxxxxxxxxxxx>

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

> ---
>  kernel/sched/fair.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
> index a80a73909dc2..05e004515fde 100644
> --- a/kernel/sched/fair.c
> +++ b/kernel/sched/fair.c
> @@ -4654,7 +4654,7 @@ static inline void update_misfit_status(struct task_struct *p, struct rq *rq)
>
>  static inline bool cfs_rq_is_decayed(struct cfs_rq *cfs_rq)
>  {
> -       return true;
> +       return !(cfs_rq->nr_running);
>  }
>
>  #define UPDATE_TG      0x0
> --
> 2.41.0
>