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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>
This commit is contained in:
Vincent Guittot 2015-02-27 16:54:04 +01:00 committed by Ingo Molnar
parent b6366f048e
commit 36ee28e45d
4 changed files with 89 additions and 24 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

21
include/linux/sched.h
View File

@ -1115,15 +1115,28 @@ struct load_weight {
};
struct sched_avg {
u64 last_runnable_update;
s64 decay_count;
/*
* utilization_avg_contrib describes the amount of time that a
* sched_entity is running on a CPU. It is based on running_avg_sum
* and is scaled in the range [0..SCHED_LOAD_SCALE].
* load_avg_contrib described the amount of time that a sched_entity
* is runnable on a rq. It is based on both runnable_avg_sum and the
* weight of the task.
*/
unsigned long load_avg_contrib, utilization_avg_contrib;
/*
* These sums represent an infinite geometric series and so are bound
* above by 1024/(1-y). Thus we only need a u32 to store them for all
* choices of y < 1-2^(-32)*1024.
* running_avg_sum reflects the time that the sched_entity is
* effectively running on the CPU.
* runnable_avg_sum represents the amount of time a sched_entity is on
* a runqueue which includes the running time that is monitored by
* running_avg_sum.
*/
u32 runnable_avg_sum, runnable_avg_period;
u64 last_runnable_update;
s64 decay_count;
unsigned long load_avg_contrib;
u32 runnable_avg_sum, avg_period, running_avg_sum;
};
#ifdef CONFIG_SCHEDSTATS

10
kernel/sched/debug.c
View File

@ -71,7 +71,7 @@ static void print_cfs_group_stats(struct seq_file *m, int cpu, struct task_group
if (!se) {
struct sched_avg *avg = &cpu_rq(cpu)->avg;
P(avg->runnable_avg_sum);
P(avg->runnable_avg_period);
P(avg->avg_period);
return;
}
@ -94,7 +94,7 @@ 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.runnable_avg_period);
P(se->avg.avg_period);
P(se->avg.load_avg_contrib);
P(se->avg.decay_count);
#endif
@ -214,6 +214,8 @@ void print_cfs_rq(struct seq_file *m, int cpu, struct cfs_rq *cfs_rq)
cfs_rq->runnable_load_avg);
SEQ_printf(m, " .%-30s: %ld\n", "blocked_load_avg",
cfs_rq->blocked_load_avg);
SEQ_printf(m, " .%-30s: %ld\n", "utilization_load_avg",
cfs_rq->utilization_load_avg);
#ifdef CONFIG_FAIR_GROUP_SCHED
SEQ_printf(m, " .%-30s: %ld\n", "tg_load_contrib",
cfs_rq->tg_load_contrib);
@ -636,8 +638,10 @@ void proc_sched_show_task(struct task_struct *p, struct seq_file *m)
P(se.load.weight);
#ifdef CONFIG_SMP
P(se.avg.runnable_avg_sum);
P(se.avg.runnable_avg_period);
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);

74
kernel/sched/fair.c
View File

@ -670,6 +670,7 @@ static int select_idle_sibling(struct task_struct *p, int cpu);
static unsigned long task_h_load(struct task_struct *p);
static inline void __update_task_entity_contrib(struct sched_entity *se);
static inline void __update_task_entity_utilization(struct sched_entity *se);
/* Give new task start runnable values to heavy its load in infant time */
void init_task_runnable_average(struct task_struct *p)
@ -677,9 +678,10 @@ void init_task_runnable_average(struct task_struct *p)
u32 slice;
slice = sched_slice(task_cfs_rq(p), &p->se) >> 10;
p->se.avg.runnable_avg_sum = slice;
p->se.avg.runnable_avg_period = slice;
p->se.avg.runnable_avg_sum = p->se.avg.running_avg_sum = slice;
p->se.avg.avg_period = slice;
__update_task_entity_contrib(&p->se);
__update_task_entity_utilization(&p->se);
}
#else
void init_task_runnable_average(struct task_struct *p)
@ -1684,7 +1686,7 @@ static u64 numa_get_avg_runtime(struct task_struct *p, u64 *period)
*period = now - p->last_task_numa_placement;
} else {
delta = p->se.avg.runnable_avg_sum;
*period = p->se.avg.runnable_avg_period;
*period = p->se.avg.avg_period;
}
p->last_sum_exec_runtime = runtime;
@ -2512,7 +2514,8 @@ static u32 __compute_runnable_contrib(u64 n)
*/
static __always_inline int __update_entity_runnable_avg(u64 now,
struct sched_avg *sa,
int runnable)
int runnable,
int running)
{
u64 delta, periods;
u32 runnable_contrib;
@ -2538,7 +2541,7 @@ static __always_inline int __update_entity_runnable_avg(u64 now,
sa->last_runnable_update = now;
/* delta_w is the amount already accumulated against our next period */
delta_w = sa->runnable_avg_period % 1024;
delta_w = sa->avg_period % 1024;
if (delta + delta_w >= 1024) {
/* period roll-over */
decayed = 1;
@ -2551,7 +2554,9 @@ static __always_inline int __update_entity_runnable_avg(u64 now,
delta_w = 1024 - delta_w;
if (runnable)
sa->runnable_avg_sum += delta_w;
sa->runnable_avg_period += delta_w;
if (running)
sa->running_avg_sum += delta_w;
sa->avg_period += delta_w;
delta -= delta_w;
@ -2561,20 +2566,26 @@ static __always_inline int __update_entity_runnable_avg(u64 now,
sa->runnable_avg_sum = decay_load(sa->runnable_avg_sum,
periods + 1);
sa->runnable_avg_period = decay_load(sa->runnable_avg_period,
sa->running_avg_sum = decay_load(sa->running_avg_sum,
periods + 1);
sa->avg_period = decay_load(sa->avg_period,
periods + 1);
/* Efficiently calculate \sum (1..n_period) 1024*y^i */
runnable_contrib = __compute_runnable_contrib(periods);
if (runnable)
sa->runnable_avg_sum += runnable_contrib;
sa->runnable_avg_period += runnable_contrib;
if (running)
sa->running_avg_sum += runnable_contrib;
sa->avg_period += runnable_contrib;
}
/* Remainder of delta accrued against u_0` */
if (runnable)
sa->runnable_avg_sum += delta;
sa->runnable_avg_period += delta;
if (running)
sa->running_avg_sum += delta;
sa->avg_period += delta;
return decayed;
}
@ -2591,6 +2602,8 @@ 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);
return decays;
}
@ -2626,7 +2639,7 @@ static inline void __update_tg_runnable_avg(struct sched_avg *sa,
/* The fraction of a cpu used by this cfs_rq */
contrib = div_u64((u64)sa->runnable_avg_sum << NICE_0_SHIFT,
sa->runnable_avg_period + 1);
sa->avg_period + 1);
contrib -= cfs_rq->tg_runnable_contrib;
if (abs(contrib) > cfs_rq->tg_runnable_contrib / 64) {
@ -2679,7 +2692,8 @@ static inline void __update_group_entity_contrib(struct sched_entity *se)
static inline void update_rq_runnable_avg(struct rq *rq, int runnable)
{
__update_entity_runnable_avg(rq_clock_task(rq), &rq->avg, runnable);
__update_entity_runnable_avg(rq_clock_task(rq), &rq->avg, runnable,
runnable);
__update_tg_runnable_avg(&rq->avg, &rq->cfs);
}
#else /* CONFIG_FAIR_GROUP_SCHED */
@ -2697,7 +2711,7 @@ static inline void __update_task_entity_contrib(struct sched_entity *se)
/* avoid overflowing a 32-bit type w/ SCHED_LOAD_SCALE */
contrib = se->avg.runnable_avg_sum * scale_load_down(se->load.weight);
contrib /= (se->avg.runnable_avg_period + 1);
contrib /= (se->avg.avg_period + 1);
se->avg.load_avg_contrib = scale_load(contrib);
}
@ -2716,6 +2730,27 @@ static long __update_entity_load_avg_contrib(struct sched_entity *se)
return se->avg.load_avg_contrib - old_contrib;
}
static inline void __update_task_entity_utilization(struct sched_entity *se)
{
u32 contrib;
/* avoid overflowing a 32-bit type w/ SCHED_LOAD_SCALE */
contrib = se->avg.running_avg_sum * scale_load_down(SCHED_LOAD_SCALE);
contrib /= (se->avg.avg_period + 1);
se->avg.utilization_avg_contrib = scale_load(contrib);
}
static long __update_entity_utilization_avg_contrib(struct sched_entity *se)
{
long old_contrib = se->avg.utilization_avg_contrib;
if (entity_is_task(se))
__update_task_entity_utilization(se);
return se->avg.utilization_avg_contrib - old_contrib;
}
static inline void subtract_blocked_load_contrib(struct cfs_rq *cfs_rq,
long load_contrib)
{
@ -2732,7 +2767,7 @@ static inline void update_entity_load_avg(struct sched_entity *se,
int update_cfs_rq)
{
struct cfs_rq *cfs_rq = cfs_rq_of(se);
long contrib_delta;
long contrib_delta, utilization_delta;
u64 now;
/*
@ -2744,18 +2779,22 @@ static inline void update_entity_load_avg(struct sched_entity *se,
else
now = cfs_rq_clock_task(group_cfs_rq(se));
if (!__update_entity_runnable_avg(now, &se->avg, se->on_rq))
if (!__update_entity_runnable_avg(now, &se->avg, se->on_rq,
cfs_rq->curr == se))
return;
contrib_delta = __update_entity_load_avg_contrib(se);
utilization_delta = __update_entity_utilization_avg_contrib(se);
if (!update_cfs_rq)
return;
if (se->on_rq)
if (se->on_rq) {
cfs_rq->runnable_load_avg += contrib_delta;
else
cfs_rq->utilization_load_avg += utilization_delta;
} else {
subtract_blocked_load_contrib(cfs_rq, -contrib_delta);
}
}
/*
@ -2830,6 +2869,7 @@ static inline void enqueue_entity_load_avg(struct cfs_rq *cfs_rq,
}
cfs_rq->runnable_load_avg += se->avg.load_avg_contrib;
cfs_rq->utilization_load_avg += se->avg.utilization_avg_contrib;
/* we force update consideration on load-balancer moves */
update_cfs_rq_blocked_load(cfs_rq, !wakeup);
}
@ -2848,6 +2888,7 @@ static inline void dequeue_entity_load_avg(struct cfs_rq *cfs_rq,
update_cfs_rq_blocked_load(cfs_rq, !sleep);
cfs_rq->runnable_load_avg -= se->avg.load_avg_contrib;
cfs_rq->utilization_load_avg -= se->avg.utilization_avg_contrib;
if (sleep) {
cfs_rq->blocked_load_avg += se->avg.load_avg_contrib;
se->avg.decay_count = atomic64_read(&cfs_rq->decay_counter);
@ -3185,6 +3226,7 @@ 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);

8
kernel/sched/sched.h
View File

@ -363,8 +363,14 @@ struct cfs_rq {
* 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).
* runnable_load_avg is the sum of the load_avg_contrib of the
* sched_entities on the rq.
* blocked_load_avg is similar to runnable_load_avg except that its
* the blocked sched_entities on the rq.
* utilization_load_avg is the sum of the average running time of the
* sched_entities on the rq.
*/
unsigned long runnable_load_avg, blocked_load_avg;
unsigned long runnable_load_avg, blocked_load_avg, utilization_load_avg;
atomic64_t decay_counter;
u64 last_decay;
atomic_long_t removed_load;