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sched/fair: Propagate an effective runnable_load_avg

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The load balancer uses runnable_load_avg as load indicator. For
!cgroup this is:

  runnable_load_avg = \Sum se->avg.load_avg ; where se->on_rq

That is, a direct sum of all runnable tasks on that runqueue. As
opposed to load_avg, which is a sum of all tasks on the runqueue,
which includes a blocked component.

However, in the cgroup case, this comes apart since the group entities
are always runnable, even if most of their constituent entities are
blocked.

Therefore introduce a runnable_weight which for task entities is the
same as the regular weight, but for group entities is a fraction of
the entity weight and represents the runnable part of the group
runqueue.

Then propagate this load through the PELT hierarchy to arrive at an
effective runnable load avgerage -- which we should not confuse with
the canonical runnable load average.

Suggested-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Peter Zijlstra 2017-05-06 15:59:54 +02:00 committed by Ingo Molnar
parent 0e2d2aaaae
commit 1ea6c46a23
4 changed files with 124 additions and 62 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

3
include/linux/sched.h
View File

@ -331,9 +331,11 @@ struct load_weight {
struct sched_avg {
u64 last_update_time;
u64 load_sum;
u64 runnable_load_sum;
u32 util_sum;
u32 period_contrib;
unsigned long load_avg;
unsigned long runnable_load_avg;
unsigned long util_avg;
};
@ -376,6 +378,7 @@ struct sched_statistics {
struct sched_entity {
/* For load-balancing: */
struct load_weight load;
unsigned long runnable_weight;
struct rb_node run_node;
struct list_head group_node;
unsigned int on_rq;

8
kernel/sched/debug.c
View File

@ -441,9 +441,11 @@ static void print_cfs_group_stats(struct seq_file *m, int cpu, struct task_group
P_SCHEDSTAT(se->statistics.wait_count);
}
P(se->load.weight);
P(se->runnable_weight);
#ifdef CONFIG_SMP
P(se->avg.load_avg);
P(se->avg.util_avg);
P(se->avg.runnable_load_avg);
#endif
#undef PN_SCHEDSTAT
@ -558,10 +560,11 @@ void print_cfs_rq(struct seq_file *m, int cpu, struct cfs_rq *cfs_rq)
SEQ_printf(m, " .%-30s: %d\n", "nr_running", cfs_rq->nr_running);
SEQ_printf(m, " .%-30s: %ld\n", "load", cfs_rq->load.weight);
#ifdef CONFIG_SMP
SEQ_printf(m, " .%-30s: %ld\n", "runnable_weight", cfs_rq->runnable_weight);
SEQ_printf(m, " .%-30s: %lu\n", "load_avg",
cfs_rq->avg.load_avg);
SEQ_printf(m, " .%-30s: %lu\n", "runnable_load_avg",
cfs_rq->runnable_load_avg);
cfs_rq->avg.runnable_load_avg);
SEQ_printf(m, " .%-30s: %lu\n", "util_avg",
cfs_rq->avg.util_avg);
SEQ_printf(m, " .%-30s: %ld\n", "removed.load_avg",
@ -1006,10 +1009,13 @@ void proc_sched_show_task(struct task_struct *p, struct pid_namespace *ns,
"nr_involuntary_switches", (long long)p->nivcsw);
P(se.load.weight);
P(se.runnable_weight);
#ifdef CONFIG_SMP
P(se.avg.load_sum);
P(se.avg.runnable_load_sum);
P(se.avg.util_sum);
P(se.avg.load_avg);
P(se.avg.runnable_load_avg);
P(se.avg.util_avg);
P(se.avg.last_update_time);
#endif

172
kernel/sched/fair.c
View File

@ -730,8 +730,9 @@ void init_entity_runnable_average(struct sched_entity *se)
* nothing has been attached to the task group yet.
*/
if (entity_is_task(se))
sa->load_avg = scale_load_down(se->load.weight);
sa->load_sum = LOAD_AVG_MAX;
sa->runnable_load_avg = sa->load_avg = scale_load_down(se->load.weight);
sa->runnable_load_sum = sa->load_sum = LOAD_AVG_MAX;
/*
* At this point, util_avg won't be used in select_task_rq_fair anyway
*/
@ -2731,25 +2732,35 @@ account_entity_dequeue(struct cfs_rq *cfs_rq, struct sched_entity *se)
#ifdef CONFIG_SMP
/*
* XXX we want to get rid of this helper and use the full load resolution.
* XXX we want to get rid of these helpers and use the full load resolution.
*/
static inline long se_weight(struct sched_entity *se)
{
return scale_load_down(se->load.weight);
}
static inline long se_runnable(struct sched_entity *se)
{
return scale_load_down(se->runnable_weight);
}
static inline void
enqueue_runnable_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se)
{
cfs_rq->runnable_load_avg += se->avg.load_avg;
cfs_rq->runnable_load_sum += se_weight(se) * se->avg.load_sum;
cfs_rq->runnable_weight += se->runnable_weight;
cfs_rq->avg.runnable_load_avg += se->avg.runnable_load_avg;
cfs_rq->avg.runnable_load_sum += se_runnable(se) * se->avg.runnable_load_sum;
}
static inline void
dequeue_runnable_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se)
{
sub_positive(&cfs_rq->runnable_load_avg, se->avg.load_avg);
sub_positive(&cfs_rq->runnable_load_sum, se_weight(se) * se->avg.load_sum);
cfs_rq->runnable_weight -= se->runnable_weight;
sub_positive(&cfs_rq->avg.runnable_load_avg, se->avg.runnable_load_avg);
sub_positive(&cfs_rq->avg.runnable_load_sum,
se_runnable(se) * se->avg.runnable_load_sum);
}
static inline void
@ -2777,7 +2788,7 @@ dequeue_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se) { }
#endif
static void reweight_entity(struct cfs_rq *cfs_rq, struct sched_entity *se,
unsigned long weight)
unsigned long weight, unsigned long runnable)
{
if (se->on_rq) {
/* commit outstanding execution time */
@ -2788,11 +2799,17 @@ static void reweight_entity(struct cfs_rq *cfs_rq, struct sched_entity *se,
}
dequeue_load_avg(cfs_rq, se);
se->runnable_weight = runnable;
update_load_set(&se->load, weight);
#ifdef CONFIG_SMP
se->avg.load_avg = div_u64(se_weight(se) * se->avg.load_sum,
LOAD_AVG_MAX - 1024 + se->avg.period_contrib);
do {
u32 divider = LOAD_AVG_MAX - 1024 + se->avg.period_contrib;
se->avg.load_avg = div_u64(se_weight(se) * se->avg.load_sum, divider);
se->avg.runnable_load_avg =
div_u64(se_runnable(se) * se->avg.runnable_load_sum, divider);
} while (0);
#endif
enqueue_load_avg(cfs_rq, se);
@ -2809,7 +2826,7 @@ void reweight_task(struct task_struct *p, int prio)
struct load_weight *load = &se->load;
unsigned long weight = scale_load(sched_prio_to_weight[prio]);
reweight_entity(cfs_rq, se, weight);
reweight_entity(cfs_rq, se, weight, weight);
load->inv_weight = sched_prio_to_wmult[prio];
}
@ -2917,31 +2934,45 @@ static long calc_cfs_shares(struct cfs_rq *cfs_rq)
static inline int throttled_hierarchy(struct cfs_rq *cfs_rq);
static void update_cfs_shares(struct sched_entity *se)
/*
* Recomputes the group entity based on the current state of its group
* runqueue.
*/
static void update_cfs_group(struct sched_entity *se)
{
struct cfs_rq *cfs_rq = group_cfs_rq(se);
long shares;
struct cfs_rq *gcfs_rq = group_cfs_rq(se);
long shares, runnable;
if (!cfs_rq)
if (!gcfs_rq)
return;
if (throttled_hierarchy(cfs_rq))
if (throttled_hierarchy(gcfs_rq))
return;
#ifndef CONFIG_SMP
shares = READ_ONCE(cfs_rq->tg->shares);
runnable = shares = READ_ONCE(gcfs_rq->tg->shares);
if (likely(se->load.weight == shares))
return;
#else
shares = calc_cfs_shares(cfs_rq);
shares = calc_cfs_shares(gcfs_rq);
/*
* The hierarchical runnable load metric is the proportional part
* of this group's runnable_load_avg / load_avg.
*
* Note: we need to deal with very sporadic 'runnable > load' cases
* due to numerical instability.
*/
runnable = shares * gcfs_rq->avg.runnable_load_avg;
if (runnable)
runnable /= max(gcfs_rq->avg.load_avg, gcfs_rq->avg.runnable_load_avg);
#endif
reweight_entity(cfs_rq_of(se), se, shares);
reweight_entity(cfs_rq_of(se), se, shares, runnable);
}
#else /* CONFIG_FAIR_GROUP_SCHED */
static inline void update_cfs_shares(struct sched_entity *se)
static inline void update_cfs_group(struct sched_entity *se)
{
}
#endif /* CONFIG_FAIR_GROUP_SCHED */
@ -3050,7 +3081,7 @@ static u32 __accumulate_pelt_segments(u64 periods, u32 d1, u32 d3)
*/
static __always_inline u32
accumulate_sum(u64 delta, int cpu, struct sched_avg *sa,
unsigned long weight, int running, struct cfs_rq *cfs_rq)
unsigned long load, unsigned long runnable, int running)
{
unsigned long scale_freq, scale_cpu;
u32 contrib = (u32)delta; /* p == 0 -> delta < 1024 */
@ -3067,10 +3098,8 @@ accumulate_sum(u64 delta, int cpu, struct sched_avg *sa,
*/
if (periods) {
sa->load_sum = decay_load(sa->load_sum, periods);
if (cfs_rq) {
cfs_rq->runnable_load_sum =
decay_load(cfs_rq->runnable_load_sum, periods);
}
sa->runnable_load_sum =
decay_load(sa->runnable_load_sum, periods);
sa->util_sum = decay_load((u64)(sa->util_sum), periods);
/*
@ -3083,11 +3112,10 @@ accumulate_sum(u64 delta, int cpu, struct sched_avg *sa,
sa->period_contrib = delta;
contrib = cap_scale(contrib, scale_freq);
if (weight) {
sa->load_sum += weight * contrib;
if (cfs_rq)
cfs_rq->runnable_load_sum += weight * contrib;
}
if (load)
sa->load_sum += load * contrib;
if (runnable)
sa->runnable_load_sum += runnable * contrib;
if (running)
sa->util_sum += contrib * scale_cpu;
@ -3124,7 +3152,7 @@ accumulate_sum(u64 delta, int cpu, struct sched_avg *sa,
*/
static __always_inline int
___update_load_sum(u64 now, int cpu, struct sched_avg *sa,
unsigned long weight, int running, struct cfs_rq *cfs_rq)
unsigned long load, unsigned long runnable, int running)
{
u64 delta;
@ -3157,8 +3185,8 @@ ___update_load_sum(u64 now, int cpu, struct sched_avg *sa,
* this happens during idle_balance() which calls
* update_blocked_averages()
*/
if (!weight)
running = 0;
if (!load)
runnable = running = 0;
/*
* Now we know we crossed measurement unit boundaries. The *_avg
@ -3167,45 +3195,60 @@ ___update_load_sum(u64 now, int cpu, struct sched_avg *sa,
* Step 1: accumulate *_sum since last_update_time. If we haven't
* crossed period boundaries, finish.
*/
if (!accumulate_sum(delta, cpu, sa, weight, running, cfs_rq))
if (!accumulate_sum(delta, cpu, sa, load, runnable, running))
return 0;
return 1;
}
static __always_inline void
___update_load_avg(struct sched_avg *sa, unsigned long weight, struct cfs_rq *cfs_rq)
___update_load_avg(struct sched_avg *sa, unsigned long load, unsigned long runnable)
{
u32 divider = LOAD_AVG_MAX - 1024 + sa->period_contrib;
/*
* Step 2: update *_avg.
*/
sa->load_avg = div_u64(weight * sa->load_sum, divider);
if (cfs_rq) {
cfs_rq->runnable_load_avg =
div_u64(cfs_rq->runnable_load_sum, divider);
}
sa->load_avg = div_u64(load * sa->load_sum, divider);
sa->runnable_load_avg = div_u64(runnable * sa->runnable_load_sum, divider);
sa->util_avg = sa->util_sum / divider;
}
/*
* sched_entity:
*
* task:
* se_runnable() == se_weight()
*
* group: [ see update_cfs_group() ]
* se_weight() = tg->weight * grq->load_avg / tg->load_avg
* se_runnable() = se_weight(se) * grq->runnable_load_avg / grq->load_avg
*
* load_sum := runnable_sum
* load_avg = se_weight(se) * runnable_avg
*
* runnable_load_sum := runnable_sum
* runnable_load_avg = se_runnable(se) * runnable_avg
*
* XXX collapse load_sum and runnable_load_sum
*
* cfq_rs:
*
* load_sum = \Sum se_weight(se) * se->avg.load_sum
* load_avg = \Sum se->avg.load_avg
*
* runnable_load_sum = \Sum se_runnable(se) * se->avg.runnable_load_sum
* runnable_load_avg = \Sum se->avg.runable_load_avg
*/
static int
__update_load_avg_blocked_se(u64 now, int cpu, struct sched_entity *se)
{
if (___update_load_sum(now, cpu, &se->avg, 0, 0, NULL)) {
___update_load_avg(&se->avg, se_weight(se), NULL);
if (entity_is_task(se))
se->runnable_weight = se->load.weight;
if (___update_load_sum(now, cpu, &se->avg, 0, 0, 0)) {
___update_load_avg(&se->avg, se_weight(se), se_runnable(se));
return 1;
}
@ -3215,10 +3258,13 @@ __update_load_avg_blocked_se(u64 now, int cpu, struct sched_entity *se)
static int
__update_load_avg_se(u64 now, int cpu, struct cfs_rq *cfs_rq, struct sched_entity *se)
{
if (___update_load_sum(now, cpu, &se->avg, !!se->on_rq,
cfs_rq->curr == se, NULL)) {
if (entity_is_task(se))
se->runnable_weight = se->load.weight;
___update_load_avg(&se->avg, se_weight(se), NULL);
if (___update_load_sum(now, cpu, &se->avg, !!se->on_rq, !!se->on_rq,
cfs_rq->curr == se)) {
___update_load_avg(&se->avg, se_weight(se), se_runnable(se));
return 1;
}
@ -3230,8 +3276,10 @@ __update_load_avg_cfs_rq(u64 now, int cpu, struct cfs_rq *cfs_rq)
{
if (___update_load_sum(now, cpu, &cfs_rq->avg,
scale_load_down(cfs_rq->load.weight),
cfs_rq->curr != NULL, cfs_rq)) {
___update_load_avg(&cfs_rq->avg, 1, cfs_rq);
scale_load_down(cfs_rq->runnable_weight),
cfs_rq->curr != NULL)) {
___update_load_avg(&cfs_rq->avg, 1, 1);
return 1;
}
@ -3409,8 +3457,8 @@ static inline void
update_tg_cfs_runnable(struct cfs_rq *cfs_rq, struct sched_entity *se, struct cfs_rq *gcfs_rq)
{
long runnable_sum = gcfs_rq->prop_runnable_sum;
long load_avg;
s64 load_sum;
long runnable_load_avg, load_avg;
s64 runnable_load_sum, load_sum;
if (!runnable_sum)
return;
@ -3426,9 +3474,15 @@ update_tg_cfs_runnable(struct cfs_rq *cfs_rq, struct sched_entity *se, struct cf
add_positive(&cfs_rq->avg.load_avg, load_avg);
add_positive(&cfs_rq->avg.load_sum, load_sum);
runnable_load_sum = (s64)se_runnable(se) * runnable_sum;
runnable_load_avg = div_s64(runnable_load_sum, LOAD_AVG_MAX);
add_positive(&se->avg.runnable_load_sum, runnable_sum);
add_positive(&se->avg.runnable_load_avg, runnable_load_avg);
if (se->on_rq) {
add_positive(&cfs_rq->runnable_load_avg, load_avg);
add_positive(&cfs_rq->runnable_load_sum, load_sum);
add_positive(&cfs_rq->avg.runnable_load_avg, runnable_load_avg);
add_positive(&cfs_rq->avg.runnable_load_sum, runnable_load_sum);
}
}
@ -3710,7 +3764,7 @@ void remove_entity_load_avg(struct sched_entity *se)
static inline unsigned long cfs_rq_runnable_load_avg(struct cfs_rq *cfs_rq)
{
return cfs_rq->runnable_load_avg;
return cfs_rq->avg.runnable_load_avg;
}
static inline unsigned long cfs_rq_load_avg(struct cfs_rq *cfs_rq)
@ -3882,8 +3936,8 @@ enqueue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags)
* - Add its new weight to cfs_rq->load.weight
*/
update_load_avg(cfs_rq, se, UPDATE_TG | DO_ATTACH);
update_cfs_group(se);
enqueue_runnable_load_avg(cfs_rq, se);
update_cfs_shares(se);
account_entity_enqueue(cfs_rq, se);
if (flags & ENQUEUE_WAKEUP)
@ -3989,7 +4043,7 @@ dequeue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags)
/* return excess runtime on last dequeue */
return_cfs_rq_runtime(cfs_rq);
update_cfs_shares(se);
update_cfs_group(se);
/*
* Now advance min_vruntime if @se was the entity holding it back,
@ -4172,7 +4226,7 @@ entity_tick(struct cfs_rq *cfs_rq, struct sched_entity *curr, int queued)
* Ensure that runnable average is periodically updated.
*/
update_load_avg(cfs_rq, curr, UPDATE_TG);
update_cfs_shares(curr);
update_cfs_group(curr);
#ifdef CONFIG_SCHED_HRTICK
/*
@ -5090,7 +5144,7 @@ enqueue_task_fair(struct rq *rq, struct task_struct *p, int flags)
break;
update_load_avg(cfs_rq, se, UPDATE_TG);
update_cfs_shares(se);
update_cfs_group(se);
}
if (!se)
@ -5149,7 +5203,7 @@ static void dequeue_task_fair(struct rq *rq, struct task_struct *p, int flags)
break;
update_load_avg(cfs_rq, se, UPDATE_TG);
update_cfs_shares(se);
update_cfs_group(se);
}
if (!se)
@ -7174,7 +7228,7 @@ static inline bool cfs_rq_is_decayed(struct cfs_rq *cfs_rq)
if (cfs_rq->avg.util_sum)
return false;
if (cfs_rq->runnable_load_sum)
if (cfs_rq->avg.runnable_load_sum)
return false;
return true;
@ -9692,7 +9746,7 @@ int sched_group_set_shares(struct task_group *tg, unsigned long shares)
update_rq_clock(rq);
for_each_sched_entity(se) {
update_load_avg(cfs_rq_of(se), se, UPDATE_TG);
update_cfs_shares(se);
update_cfs_group(se);
}
rq_unlock_irqrestore(rq, &rf);
}

3
kernel/sched/sched.h
View File

@ -418,6 +418,7 @@ struct cfs_bandwidth { };
/* CFS-related fields in a runqueue */
struct cfs_rq {
struct load_weight load;
unsigned long runnable_weight;
unsigned int nr_running, h_nr_running;
u64 exec_clock;
@ -443,8 +444,6 @@ struct cfs_rq {
* CFS load tracking
*/
struct sched_avg avg;
u64 runnable_load_sum;
unsigned long runnable_load_avg;
#ifndef CONFIG_64BIT
u64 load_last_update_time_copy;
#endif