Re: [PATCH] sched/debug: Show intergroup and hierarchy sum wait time of a task group

From: Peter Zijlstra
Date: Wed Feb 06 2019 - 12:19:35 EST


On Wed, Jan 23, 2019 at 05:46:56PM +0800, ufo19890607@xxxxxxxxx wrote:
> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
> index e2ff4b6..35e89ca 100644
> --- a/kernel/sched/fair.c
> +++ b/kernel/sched/fair.c
> @@ -858,6 +858,19 @@ static void update_curr_fair(struct rq *rq)
> }
>
> static inline void
> +update_hierarchy_wait_sum(struct sched_entity *se,
> + u64 delta_wait)
> +{
> + for_each_sched_entity(se) {
> + struct cfs_rq *cfs_rq = cfs_rq_of(se);
> +
> + if (cfs_rq->tg != &root_task_group)
> + __schedstat_add(cfs_rq->hierarchy_wait_sum,
> + delta_wait);
> + }
> +}
> +
> +static inline void
> update_stats_wait_end(struct cfs_rq *cfs_rq, struct sched_entity *se)
> {
> struct task_struct *p;
> @@ -880,6 +893,7 @@ static void update_curr_fair(struct rq *rq)
> return;
> }
> trace_sched_stat_wait(p, delta);
> + update_hierarchy_wait_sum(se, delta);
> }
>
> __schedstat_set(se->statistics.wait_max,

The problem I have with this is that it will make schedstats even more
expensive :/