sched: Add sched_avg::utilization_avg_contrib
Add new statistics which reflect the average time a task is running on the CPU and the sum of these running time of the tasks on a runqueue. The latter is named utilization_load_avg. This patch is based on the usage metric that was proposed in the 1st versions of the per-entity load tracking patchset by Paul Turner <pjt@google.com> but that has be removed afterwards. This version differs from the original one in the sense that it's not linked to task_group. The rq's utilization_load_avg will be used to check if a rq is overloaded or not instead of trying to compute how many tasks a group of CPUs can handle. Rename runnable_avg_period into avg_period as it is now used with both runnable_avg_sum and running_avg_sum. Add some descriptions of the variables to explain their differences. Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Morten Rasmussen <morten.rasmussen@arm.com> Cc: Paul Turner <pjt@google.com> Cc: Ben Segall <bsegall@google.com> Cc: Ben Segall <bsegall@google.com> Cc: Morten.Rasmussen@arm.com Cc: Paul Turner <pjt@google.com> Cc: dietmar.eggemann@arm.com Cc: efault@gmx.de Cc: kamalesh@linux.vnet.ibm.com Cc: linaro-kernel@lists.linaro.org Cc: nicolas.pitre@linaro.org Cc: preeti@linux.vnet.ibm.com Cc: riel@redhat.com Link: http://lkml.kernel.org/r/1425052454-25797-2-git-send-email-vincent.guittot@linaro.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
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@ -1115,15 +1115,28 @@ struct load_weight {
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};
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struct sched_avg {
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u64 last_runnable_update;
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s64 decay_count;
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/*
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* utilization_avg_contrib describes the amount of time that a
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* sched_entity is running on a CPU. It is based on running_avg_sum
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* and is scaled in the range [0..SCHED_LOAD_SCALE].
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* load_avg_contrib described the amount of time that a sched_entity
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* is runnable on a rq. It is based on both runnable_avg_sum and the
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* weight of the task.
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*/
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unsigned long load_avg_contrib, utilization_avg_contrib;
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/*
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* These sums represent an infinite geometric series and so are bound
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* above by 1024/(1-y). Thus we only need a u32 to store them for all
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* choices of y < 1-2^(-32)*1024.
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* running_avg_sum reflects the time that the sched_entity is
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* effectively running on the CPU.
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* runnable_avg_sum represents the amount of time a sched_entity is on
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* a runqueue which includes the running time that is monitored by
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* running_avg_sum.
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*/
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u32 runnable_avg_sum, runnable_avg_period;
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u64 last_runnable_update;
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s64 decay_count;
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unsigned long load_avg_contrib;
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u32 runnable_avg_sum, avg_period, running_avg_sum;
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};
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#ifdef CONFIG_SCHEDSTATS
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@ -71,7 +71,7 @@ static void print_cfs_group_stats(struct seq_file *m, int cpu, struct task_group
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if (!se) {
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struct sched_avg *avg = &cpu_rq(cpu)->avg;
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P(avg->runnable_avg_sum);
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P(avg->runnable_avg_period);
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P(avg->avg_period);
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return;
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}
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@ -94,7 +94,7 @@ static void print_cfs_group_stats(struct seq_file *m, int cpu, struct task_group
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P(se->load.weight);
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#ifdef CONFIG_SMP
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P(se->avg.runnable_avg_sum);
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P(se->avg.runnable_avg_period);
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P(se->avg.avg_period);
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P(se->avg.load_avg_contrib);
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P(se->avg.decay_count);
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#endif
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@ -214,6 +214,8 @@ void print_cfs_rq(struct seq_file *m, int cpu, struct cfs_rq *cfs_rq)
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cfs_rq->runnable_load_avg);
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SEQ_printf(m, " .%-30s: %ld\n", "blocked_load_avg",
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cfs_rq->blocked_load_avg);
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SEQ_printf(m, " .%-30s: %ld\n", "utilization_load_avg",
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cfs_rq->utilization_load_avg);
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#ifdef CONFIG_FAIR_GROUP_SCHED
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SEQ_printf(m, " .%-30s: %ld\n", "tg_load_contrib",
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cfs_rq->tg_load_contrib);
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@ -636,8 +638,10 @@ void proc_sched_show_task(struct task_struct *p, struct seq_file *m)
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P(se.load.weight);
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#ifdef CONFIG_SMP
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P(se.avg.runnable_avg_sum);
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P(se.avg.runnable_avg_period);
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P(se.avg.running_avg_sum);
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P(se.avg.avg_period);
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P(se.avg.load_avg_contrib);
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P(se.avg.utilization_avg_contrib);
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P(se.avg.decay_count);
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#endif
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P(policy);
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@ -670,6 +670,7 @@ static int select_idle_sibling(struct task_struct *p, int cpu);
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static unsigned long task_h_load(struct task_struct *p);
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static inline void __update_task_entity_contrib(struct sched_entity *se);
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static inline void __update_task_entity_utilization(struct sched_entity *se);
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/* Give new task start runnable values to heavy its load in infant time */
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void init_task_runnable_average(struct task_struct *p)
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@ -677,9 +678,10 @@ void init_task_runnable_average(struct task_struct *p)
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u32 slice;
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slice = sched_slice(task_cfs_rq(p), &p->se) >> 10;
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p->se.avg.runnable_avg_sum = slice;
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p->se.avg.runnable_avg_period = slice;
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p->se.avg.runnable_avg_sum = p->se.avg.running_avg_sum = slice;
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p->se.avg.avg_period = slice;
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__update_task_entity_contrib(&p->se);
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__update_task_entity_utilization(&p->se);
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}
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#else
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void init_task_runnable_average(struct task_struct *p)
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@ -1684,7 +1686,7 @@ static u64 numa_get_avg_runtime(struct task_struct *p, u64 *period)
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*period = now - p->last_task_numa_placement;
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} else {
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delta = p->se.avg.runnable_avg_sum;
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*period = p->se.avg.runnable_avg_period;
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*period = p->se.avg.avg_period;
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}
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p->last_sum_exec_runtime = runtime;
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@ -2512,7 +2514,8 @@ static u32 __compute_runnable_contrib(u64 n)
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*/
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static __always_inline int __update_entity_runnable_avg(u64 now,
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struct sched_avg *sa,
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int runnable)
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int runnable,
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int running)
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{
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u64 delta, periods;
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u32 runnable_contrib;
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@ -2538,7 +2541,7 @@ static __always_inline int __update_entity_runnable_avg(u64 now,
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sa->last_runnable_update = now;
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/* delta_w is the amount already accumulated against our next period */
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delta_w = sa->runnable_avg_period % 1024;
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delta_w = sa->avg_period % 1024;
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if (delta + delta_w >= 1024) {
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/* period roll-over */
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decayed = 1;
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@ -2551,7 +2554,9 @@ static __always_inline int __update_entity_runnable_avg(u64 now,
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delta_w = 1024 - delta_w;
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if (runnable)
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sa->runnable_avg_sum += delta_w;
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sa->runnable_avg_period += delta_w;
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if (running)
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sa->running_avg_sum += delta_w;
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sa->avg_period += delta_w;
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delta -= delta_w;
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@ -2561,20 +2566,26 @@ static __always_inline int __update_entity_runnable_avg(u64 now,
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sa->runnable_avg_sum = decay_load(sa->runnable_avg_sum,
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periods + 1);
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sa->runnable_avg_period = decay_load(sa->runnable_avg_period,
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sa->running_avg_sum = decay_load(sa->running_avg_sum,
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periods + 1);
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sa->avg_period = decay_load(sa->avg_period,
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periods + 1);
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/* Efficiently calculate \sum (1..n_period) 1024*y^i */
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runnable_contrib = __compute_runnable_contrib(periods);
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if (runnable)
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sa->runnable_avg_sum += runnable_contrib;
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sa->runnable_avg_period += runnable_contrib;
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if (running)
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sa->running_avg_sum += runnable_contrib;
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sa->avg_period += runnable_contrib;
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}
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/* Remainder of delta accrued against u_0` */
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if (runnable)
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sa->runnable_avg_sum += delta;
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sa->runnable_avg_period += delta;
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if (running)
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sa->running_avg_sum += delta;
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sa->avg_period += delta;
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return decayed;
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}
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@ -2591,6 +2602,8 @@ static inline u64 __synchronize_entity_decay(struct sched_entity *se)
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return 0;
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se->avg.load_avg_contrib = decay_load(se->avg.load_avg_contrib, decays);
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se->avg.utilization_avg_contrib =
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decay_load(se->avg.utilization_avg_contrib, decays);
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return decays;
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}
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@ -2626,7 +2639,7 @@ static inline void __update_tg_runnable_avg(struct sched_avg *sa,
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/* The fraction of a cpu used by this cfs_rq */
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contrib = div_u64((u64)sa->runnable_avg_sum << NICE_0_SHIFT,
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sa->runnable_avg_period + 1);
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sa->avg_period + 1);
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contrib -= cfs_rq->tg_runnable_contrib;
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if (abs(contrib) > cfs_rq->tg_runnable_contrib / 64) {
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@ -2679,7 +2692,8 @@ static inline void __update_group_entity_contrib(struct sched_entity *se)
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static inline void update_rq_runnable_avg(struct rq *rq, int runnable)
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{
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__update_entity_runnable_avg(rq_clock_task(rq), &rq->avg, runnable);
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__update_entity_runnable_avg(rq_clock_task(rq), &rq->avg, runnable,
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runnable);
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__update_tg_runnable_avg(&rq->avg, &rq->cfs);
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}
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#else /* CONFIG_FAIR_GROUP_SCHED */
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@ -2697,7 +2711,7 @@ static inline void __update_task_entity_contrib(struct sched_entity *se)
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/* avoid overflowing a 32-bit type w/ SCHED_LOAD_SCALE */
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contrib = se->avg.runnable_avg_sum * scale_load_down(se->load.weight);
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contrib /= (se->avg.runnable_avg_period + 1);
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contrib /= (se->avg.avg_period + 1);
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se->avg.load_avg_contrib = scale_load(contrib);
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}
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@ -2716,6 +2730,27 @@ static long __update_entity_load_avg_contrib(struct sched_entity *se)
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return se->avg.load_avg_contrib - old_contrib;
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}
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static inline void __update_task_entity_utilization(struct sched_entity *se)
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{
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u32 contrib;
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/* avoid overflowing a 32-bit type w/ SCHED_LOAD_SCALE */
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contrib = se->avg.running_avg_sum * scale_load_down(SCHED_LOAD_SCALE);
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contrib /= (se->avg.avg_period + 1);
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se->avg.utilization_avg_contrib = scale_load(contrib);
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}
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static long __update_entity_utilization_avg_contrib(struct sched_entity *se)
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{
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long old_contrib = se->avg.utilization_avg_contrib;
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if (entity_is_task(se))
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__update_task_entity_utilization(se);
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return se->avg.utilization_avg_contrib - old_contrib;
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}
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static inline void subtract_blocked_load_contrib(struct cfs_rq *cfs_rq,
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long load_contrib)
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{
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@ -2732,7 +2767,7 @@ static inline void update_entity_load_avg(struct sched_entity *se,
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int update_cfs_rq)
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{
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struct cfs_rq *cfs_rq = cfs_rq_of(se);
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long contrib_delta;
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long contrib_delta, utilization_delta;
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u64 now;
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/*
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@ -2744,19 +2779,23 @@ static inline void update_entity_load_avg(struct sched_entity *se,
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else
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now = cfs_rq_clock_task(group_cfs_rq(se));
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if (!__update_entity_runnable_avg(now, &se->avg, se->on_rq))
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if (!__update_entity_runnable_avg(now, &se->avg, se->on_rq,
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cfs_rq->curr == se))
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return;
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contrib_delta = __update_entity_load_avg_contrib(se);
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utilization_delta = __update_entity_utilization_avg_contrib(se);
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if (!update_cfs_rq)
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return;
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if (se->on_rq)
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if (se->on_rq) {
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cfs_rq->runnable_load_avg += contrib_delta;
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else
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cfs_rq->utilization_load_avg += utilization_delta;
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} else {
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subtract_blocked_load_contrib(cfs_rq, -contrib_delta);
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}
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}
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/*
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* Decay the load contributed by all blocked children and account this so that
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@ -2830,6 +2869,7 @@ static inline void enqueue_entity_load_avg(struct cfs_rq *cfs_rq,
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}
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cfs_rq->runnable_load_avg += se->avg.load_avg_contrib;
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cfs_rq->utilization_load_avg += se->avg.utilization_avg_contrib;
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/* we force update consideration on load-balancer moves */
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update_cfs_rq_blocked_load(cfs_rq, !wakeup);
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}
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@ -2848,6 +2888,7 @@ static inline void dequeue_entity_load_avg(struct cfs_rq *cfs_rq,
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update_cfs_rq_blocked_load(cfs_rq, !sleep);
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cfs_rq->runnable_load_avg -= se->avg.load_avg_contrib;
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cfs_rq->utilization_load_avg -= se->avg.utilization_avg_contrib;
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if (sleep) {
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cfs_rq->blocked_load_avg += se->avg.load_avg_contrib;
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se->avg.decay_count = atomic64_read(&cfs_rq->decay_counter);
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@ -3185,6 +3226,7 @@ set_next_entity(struct cfs_rq *cfs_rq, struct sched_entity *se)
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*/
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update_stats_wait_end(cfs_rq, se);
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__dequeue_entity(cfs_rq, se);
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update_entity_load_avg(se, 1);
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}
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update_stats_curr_start(cfs_rq, se);
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@ -363,8 +363,14 @@ struct cfs_rq {
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* Under CFS, load is tracked on a per-entity basis and aggregated up.
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* This allows for the description of both thread and group usage (in
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* the FAIR_GROUP_SCHED case).
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* runnable_load_avg is the sum of the load_avg_contrib of the
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* sched_entities on the rq.
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* blocked_load_avg is similar to runnable_load_avg except that its
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* the blocked sched_entities on the rq.
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* utilization_load_avg is the sum of the average running time of the
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* sched_entities on the rq.
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*/
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unsigned long runnable_load_avg, blocked_load_avg;
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unsigned long runnable_load_avg, blocked_load_avg, utilization_load_avg;
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atomic64_t decay_counter;
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u64 last_decay;
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atomic_long_t removed_load;
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