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SubjectRe: [PATCH 4/7] sched: Track group sched_entity usage contributions
Date
Vincent Guittot <vincent.guittot@linaro.org> writes:

> From: Morten Rasmussen <morten.rasmussen@arm.com>
>
> Adds usage contribution tracking for group entities. Unlike
> se->avg.load_avg_contrib, se->avg.utilization_avg_contrib for group
> entities is the sum of se->avg.utilization_avg_contrib for all entities on the
> group runqueue. It is _not_ influenced in any way by the task group
> h_load. Hence it is representing the actual cpu usage of the group, not
> its intended load contribution which may differ significantly from the
> utilization on lightly utilized systems.


Just noting that this version also has usage disappear immediately when
a task blocks, although it does what you probably want on migration.

Also, group-ses don't ever use their running_avg_sum so it's kinda a
waste, but I'm not sure it's worth doing anything about.

>
> cc: Paul Turner <pjt@google.com>
> cc: Ben Segall <bsegall@google.com>
>
> Signed-off-by: Morten Rasmussen <morten.rasmussen@arm.com>
> ---
> kernel/sched/debug.c | 3 +++
> kernel/sched/fair.c | 5 +++++
> 2 files changed, 8 insertions(+)
>
> diff --git a/kernel/sched/debug.c b/kernel/sched/debug.c
> index e0fbc0f..efb47ed 100644
> --- a/kernel/sched/debug.c
> +++ b/kernel/sched/debug.c
> @@ -94,8 +94,10 @@ static void print_cfs_group_stats(struct seq_file *m, int cpu, struct task_group
> P(se->load.weight);
> #ifdef CONFIG_SMP
> P(se->avg.runnable_avg_sum);
> + P(se->avg.running_avg_sum);
> P(se->avg.avg_period);
> P(se->avg.load_avg_contrib);
> + P(se->avg.utilization_avg_contrib);
> P(se->avg.decay_count);
> #endif
> #undef PN
> @@ -633,6 +635,7 @@ void proc_sched_show_task(struct task_struct *p, struct seq_file *m)
> P(se.avg.running_avg_sum);
> P(se.avg.avg_period);
> P(se.avg.load_avg_contrib);
> + P(se.avg.utilization_avg_contrib);
> P(se.avg.decay_count);
> #endif
> P(policy);
> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
> index d6de526..d3e9067 100644
> --- a/kernel/sched/fair.c
> +++ b/kernel/sched/fair.c
> @@ -2381,6 +2381,8 @@ static inline u64 __synchronize_entity_decay(struct sched_entity *se)
> return 0;
>
> se->avg.load_avg_contrib = decay_load(se->avg.load_avg_contrib, decays);
> + se->avg.utilization_avg_contrib =
> + decay_load(se->avg.utilization_avg_contrib, decays);
> se->avg.decay_count = 0;
>
> return decays;
> @@ -2525,6 +2527,9 @@ static long __update_entity_utilization_avg_contrib(struct sched_entity *se)
>
> if (entity_is_task(se))
> __update_task_entity_utilization(se);
> + else
> + se->avg.utilization_avg_contrib =
> + group_cfs_rq(se)->utilization_load_avg;
>
> return se->avg.utilization_avg_contrib - old_contrib;
> }


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