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Message-ID: <CAKfTPtAFT-GH2SzE1--XQVaay+bwATcLOqxFpH_z=byo=ix=uw@mail.gmail.com>
Date: Tue, 13 Mar 2012 17:57:52 +0100
From: Vincent Guittot <vincent.guittot@...aro.org>
To: Paul Turner <pjt@...gle.com>
Cc: linux-kernel@...r.kernel.org, Venki Pallipadi <venki@...gle.com>,
Srivatsa Vaddagiri <vatsa@...ibm.com>,
Peter Zijlstra <a.p.zijlstra@...llo.nl>,
Mike Galbraith <efault@....de>,
Kamalesh Babulal <kamalesh@...ux.vnet.ibm.com>,
Ben Segall <bsegall@...gle.com>, Ingo Molnar <mingo@...e.hu>,
Vaidyanathan Srinivasan <svaidy@...ux.vnet.ibm.com>
Subject: Re: [RFC PATCH 14/14] sched: implement usage tracking
Hi Paul,
On 2 February 2012 02:38, Paul Turner <pjt@...gle.com> wrote:
> With the frame-work for runnable tracking now fully in place. Per-entity usage
> tracking is a simple and low-overhead addition.
>
> Signed-off-by: Paul Turner <pjt@...gle.com>
> Signed-off-by: Ben Segall <bsegall@...gle.com>
> ---
> include/linux/sched.h | 1 +
> kernel/sched/debug.c | 3 +++
> kernel/sched/fair.c | 29 +++++++++++++++++++++++------
> kernel/sched/sched.h | 4 ++--
> 4 files changed, 29 insertions(+), 8 deletions(-)
>
> diff --git a/include/linux/sched.h b/include/linux/sched.h
> index 09b8c45..209185f 100644
> --- a/include/linux/sched.h
> +++ b/include/linux/sched.h
> @@ -1159,6 +1159,7 @@ struct load_weight {
> struct sched_avg {
> u64 runnable_avg_sum, runnable_avg_period;
> u64 last_runnable_update, decay_count;
> + u32 usage_avg_sum;
Why usage_avg_sum is 32bits whereas runnable_avg_sum and
runnable_avg_period are 64bits long ? You are doing the same
computation on these 3 variables. Only the computation need to be done
in 64bits but the result could be saved in 32bits ?
Regards,
Vincent
> unsigned long load_avg_contrib;
>
> int contributes_blocked_load;
> diff --git a/kernel/sched/debug.c b/kernel/sched/debug.c
> index 0911ec6..4d39069 100644
> --- a/kernel/sched/debug.c
> +++ b/kernel/sched/debug.c
> @@ -93,6 +93,7 @@ static void print_cfs_group_stats(struct seq_file *m, int cpu, struct task_group
> P(se->load.weight);
> P(se->avg.runnable_avg_sum);
> P(se->avg.runnable_avg_period);
> + P(se->avg.usage_avg_sum);
> P(se->avg.load_avg_contrib);
> P(se->avg.decay_count);
> #undef PN
> @@ -228,6 +229,8 @@ void print_cfs_rq(struct seq_file *m, int cpu, struct cfs_rq *cfs_rq)
> cfs_rq->tg_runnable_contrib);
> SEQ_printf(m, " .%-30s: %d\n", "tg->runnable_avg",
> atomic_read(&cfs_rq->tg->runnable_avg));
> + SEQ_printf(m, " .%-30s: %d\n", "tg->usage_avg",
> + atomic_read(&cfs_rq->tg->usage_avg));
> #endif
>
> print_cfs_group_stats(m, cpu, cfs_rq->tg);
> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
> index ad524bb..222c2c9 100644
> --- a/kernel/sched/fair.c
> +++ b/kernel/sched/fair.c
> @@ -997,7 +997,8 @@ static u32 __compute_runnable_contrib(int n)
> */
> static __always_inline int __update_entity_runnable_avg(u64 now,
> struct sched_avg *sa,
> - int runnable)
> + int runnable,
> + int running)
> {
> u64 delta;
> u32 periods, runnable_contrib;
> @@ -1026,6 +1027,8 @@ static __always_inline int __update_entity_runnable_avg(u64 now,
> delta_w = 1024 - delta_w;
> if (runnable)
> sa->runnable_avg_sum += delta_w;
> + if (running)
> + sa->usage_avg_sum += delta_w;
> sa->runnable_avg_period += delta_w;
>
> delta -= delta_w;
> @@ -1036,15 +1039,20 @@ static __always_inline int __update_entity_runnable_avg(u64 now,
> periods + 1);
> sa->runnable_avg_period = decay_load(sa->runnable_avg_period,
> periods + 1);
> + sa->usage_avg_sum = decay_load(sa->usage_avg_sum, periods + 1);
>
> runnable_contrib = __compute_runnable_contrib(periods);
> if (runnable)
> sa->runnable_avg_sum += runnable_contrib;
> + if (running)
> + sa->usage_avg_sum += runnable_contrib;
> sa->runnable_avg_period += runnable_contrib;
> }
>
> if (runnable)
> sa->runnable_avg_sum += delta;
> + if (running)
> + sa->usage_avg_sum += delta;
> sa->runnable_avg_period += delta;
>
> return decayed;
> @@ -1081,14 +1089,21 @@ static inline void __update_tg_runnable_avg(struct sched_avg *sa,
> struct cfs_rq *cfs_rq)
> {
> struct task_group *tg = cfs_rq->tg;
> - long contrib;
> + long contrib, usage_contrib;
>
> contrib = (sa->runnable_avg_sum << 12) / (sa->runnable_avg_period + 1);
> contrib -= cfs_rq->tg_runnable_contrib;
>
> - if (abs(contrib) > cfs_rq->tg_runnable_contrib/64) {
> + usage_contrib = (sa->usage_avg_sum << 12) / (sa->runnable_avg_period + 1);
> + usage_contrib -= cfs_rq->tg_usage_contrib;
> +
> + if ((abs(contrib) > cfs_rq->tg_runnable_contrib/64) ||
> + (abs(usage_contrib) > cfs_rq->tg_usage_contrib/64)) {
> atomic_add(contrib, &tg->runnable_avg);
> cfs_rq->tg_runnable_contrib += contrib;
> +
> + atomic_add(usage_contrib, &tg->usage_avg);
> + cfs_rq->tg_usage_contrib += usage_contrib;
> }
> }
>
> @@ -1164,8 +1179,8 @@ static inline void update_entity_load_avg(struct sched_entity *se,
> 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))
> + if(!__update_entity_runnable_avg(cfs_rq_clock_task(cfs_rq), &se->avg,
> + se->on_rq, cfs_rq->curr == se))
> return;
>
> contrib_delta = __update_entity_load_avg_contrib(se);
> @@ -1210,7 +1225,8 @@ static void update_cfs_rq_blocked_load(struct cfs_rq *cfs_rq, int force_update)
>
> static inline void update_rq_runnable_avg(struct rq *rq, int runnable)
> {
> - __update_entity_runnable_avg(rq->clock_task, &rq->avg, runnable);
> + __update_entity_runnable_avg(rq->clock_task, &rq->avg, runnable,
> + runnable);
> __update_tg_runnable_avg(&rq->avg, &rq->cfs);
> }
>
> @@ -1590,6 +1606,7 @@ set_next_entity(struct cfs_rq *cfs_rq, struct sched_entity *se)
> */
> update_stats_wait_end(cfs_rq, se);
> __dequeue_entity(cfs_rq, se);
> + update_entity_load_avg(se, 1);
> }
>
> update_stats_curr_start(cfs_rq, se);
> diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
> index 77f3297..9602a47 100644
> --- a/kernel/sched/sched.h
> +++ b/kernel/sched/sched.h
> @@ -117,7 +117,7 @@ struct task_group {
>
> atomic_t load_weight;
> atomic64_t load_avg;
> - atomic_t runnable_avg;
> + atomic_t runnable_avg, usage_avg;
> #endif
>
> #ifdef CONFIG_RT_GROUP_SCHED
> @@ -260,7 +260,7 @@ struct cfs_rq {
> */
> unsigned long h_load;
>
> - u32 tg_runnable_contrib;
> + u32 tg_runnable_contrib, tg_usage_contrib;
> u64 runnable_load_avg, blocked_load_avg;
> u64 tg_load_contrib;
> atomic64_t decay_counter, removed_load;
>
>
> --
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