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SubjectRe: [PATCH 03/16] sched: aggregate load contributed by task entities on parenting cfs_rq
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On Wed, 27 Jun 2012 19:24:14 -0700, Paul Turner wrote:
> For a given task t, we can compute its contribution to load as:
> task_load(t) = runnable_avg(t) * weight(t)
>
> On a parenting cfs_rq we can then aggregate
> runnable_load(cfs_rq) = \Sum task_load(t), for all runnable children t
>
> Maintain this bottom up, with task entities adding their contributed load to
> the parenting cfs_rq sum. When a task entities load changes we add the same
entity's ?

> delta to the maintained sum.
>
> Signed-off-by: Paul Turner <pjt@google.com>
> Signed-off-by: Ben Segall <bsegall@google.com>
> ---
> include/linux/sched.h | 1 +
> kernel/sched/debug.c | 3 +++
> kernel/sched/fair.c | 51 +++++++++++++++++++++++++++++++++++++++++++++----
> kernel/sched/sched.h | 10 +++++++++-
> 4 files changed, 60 insertions(+), 5 deletions(-)
>
> diff --git a/include/linux/sched.h b/include/linux/sched.h
> index 5bf5c79..0c54ce0 100644
> --- a/include/linux/sched.h
> +++ b/include/linux/sched.h
> @@ -1139,6 +1139,7 @@ struct load_weight {
> struct sched_avg {
> u32 runnable_avg_sum, runnable_avg_period;
> u64 last_runnable_update;
> + unsigned long load_avg_contrib;
> };
>
> #ifdef CONFIG_SCHEDSTATS
> diff --git a/kernel/sched/debug.c b/kernel/sched/debug.c
> index 5d4a7dd..aeb74e3 100644
> --- a/kernel/sched/debug.c
> +++ b/kernel/sched/debug.c
> @@ -94,6 +94,7 @@ static void print_cfs_group_stats(struct seq_file *m, int cpu, struct task_group
> #ifdef CONFIG_SMP
> P(se->avg.runnable_avg_sum);
> P(se->avg.runnable_avg_period);
> + P(se->avg.load_avg_contrib);
> #endif
> #undef PN
> #undef P
> @@ -227,6 +228,8 @@ void print_cfs_rq(struct seq_file *m, int cpu, struct cfs_rq *cfs_rq)
> cfs_rq->load_contribution);
> SEQ_printf(m, " .%-30s: %d\n", "load_tg",
> atomic_read(&cfs_rq->tg->load_weight));
> + SEQ_printf(m, " .%-30s: %lld\n", "runnable_load_avg",
> + cfs_rq->runnable_load_avg);
> #endif
>
> print_cfs_group_stats(m, cpu, cfs_rq->tg);
> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
> index 08bd3e0..8229766 100644
> --- a/kernel/sched/fair.c
> +++ b/kernel/sched/fair.c
> @@ -1085,20 +1085,63 @@ static __always_inline int __update_entity_runnable_avg(u64 now,
> return decayed;
> }
>
> +/* Compute the current contribution to load_avg by se, return any delta */
> +static long __update_entity_load_avg_contrib(struct sched_entity *se)
> +{
> + long old_contrib = se->avg.load_avg_contrib;
> +
> + if (!entity_is_task(se))
> + return 0;
> +
> + se->avg.load_avg_contrib = div64_u64(se->avg.runnable_avg_sum *
> + se->load.weight,
> + se->avg.runnable_avg_period + 1);
> +
> + return se->avg.load_avg_contrib - old_contrib;
> +}
> +
> /* Update a sched_entity's runnable average */
> static inline void update_entity_load_avg(struct sched_entity *se)
> {
> - __update_entity_runnable_avg(rq_of(cfs_rq_of(se))->clock_task, &se->avg,
> - se->on_rq);
> + struct cfs_rq *cfs_rq = cfs_rq_of(se);
> + long contrib_delta;
> +
> + if (!__update_entity_runnable_avg(rq_of(cfs_rq)->clock_task, &se->avg,
> + se->on_rq))

Ok, now I see that the return value is used here.

Thanks,
Namhyung


> + return;
> +
> + contrib_delta = __update_entity_load_avg_contrib(se);
> + if (se->on_rq)
> + cfs_rq->runnable_load_avg += contrib_delta;
> }
>
> static inline void update_rq_runnable_avg(struct rq *rq, int runnable)
> {
> __update_entity_runnable_avg(rq->clock_task, &rq->avg, runnable);
> }
> +
> +/* Add the load generated by se into cfs_rq's child load-average */
> +static inline void enqueue_entity_load_avg(struct cfs_rq *cfs_rq,
> + struct sched_entity *se)
> +{
> + update_entity_load_avg(se);
> + cfs_rq->runnable_load_avg += se->avg.load_avg_contrib;
> +}
> +
> +/* Remove se's load from this cfs_rq child load-average */
> +static inline void dequeue_entity_load_avg(struct cfs_rq *cfs_rq,
> + struct sched_entity *se)
> +{
> + update_entity_load_avg(se);
> + cfs_rq->runnable_load_avg -= se->avg.load_avg_contrib;
> +}
> #else
> static inline void update_entity_load_avg(struct sched_entity *se) {}
> static inline void update_rq_runnable_avg(struct rq *rq, int runnable) {}
> +static inline void enqueue_entity_load_avg(struct cfs_rq *cfs_rq,
> + struct sched_entity *se) {}
> +static inline void dequeue_entity_load_avg(struct cfs_rq *cfs_rq,
> + struct sched_entity *se) {}
> #endif
>
> static void enqueue_sleeper(struct cfs_rq *cfs_rq, struct sched_entity *se)
> @@ -1227,7 +1270,7 @@ enqueue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags)
> */
> update_curr(cfs_rq);
> update_cfs_load(cfs_rq, 0);
> - update_entity_load_avg(se);
> + enqueue_entity_load_avg(cfs_rq, se);
> account_entity_enqueue(cfs_rq, se);
> update_cfs_shares(cfs_rq);
>
> @@ -1302,7 +1345,7 @@ dequeue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags)
> * Update run-time statistics of the 'current'.
> */
> update_curr(cfs_rq);
> - update_entity_load_avg(se);
> + dequeue_entity_load_avg(cfs_rq, se);
>
> update_stats_dequeue(cfs_rq, se);
> if (flags & DEQUEUE_SLEEP) {
> diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
> index bfdb119..26cc36f 100644
> --- a/kernel/sched/sched.h
> +++ b/kernel/sched/sched.h
> @@ -222,6 +222,15 @@ struct cfs_rq {
> unsigned int nr_spread_over;
> #endif
>
> +#ifdef CONFIG_SMP
> + /*
> + * CFS Load tracking
> + * Under CFS, load is tracked on a per-entity basis and aggregated up.
> + * This allows for the description of both thread and group usage (in
> + * the FAIR_GROUP_SCHED case).
> + */
> + u64 runnable_load_avg;
> +#endif
> #ifdef CONFIG_FAIR_GROUP_SCHED
> struct rq *rq; /* cpu runqueue to which this cfs_rq is attached */
>
> @@ -1204,4 +1213,3 @@ static inline void account_numa_dequeue(struct task_struct *p) { }
> static inline void init_sched_numa(void) { }
>
> #endif /* CONFIG_NUMA */
> -


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