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sched/fair: Factorize PELT update
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Every time we modify load/utilization of sched_entity, we start to
sync it with its cfs_rq. This update is done in different ways:

 - when attaching/detaching a sched_entity, we update cfs_rq and then
   we sync the entity with the cfs_rq.

 - when enqueueing/dequeuing the sched_entity, we update both
   sched_entity and cfs_rq metrics to now.

Use update_load_avg() everytime we have to update and sync cfs_rq and
sched_entity before changing the state of a sched_enity.

Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Morten.Rasmussen@arm.com
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: bsegall@google.com
Cc: kernellwp@gmail.com
Cc: pjt@google.com
Cc: yuyang.du@intel.com
Link: http://lkml.kernel.org/r/1478598827-32372-4-git-send-email-vincent.guittot@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Vincent Guittot authored and Ingo Molnar committed Nov 16, 2016
1 parent 9c2791f commit d31b1a6
Showing 1 changed file with 25 additions and 51 deletions.
76 changes: 25 additions & 51 deletions kernel/sched/fair.c
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Original file line number Diff line number Diff line change
Expand Up @@ -3092,8 +3092,14 @@ update_cfs_rq_load_avg(u64 now, struct cfs_rq *cfs_rq, bool update_freq)
return decayed || removed_load;
}

/*
* Optional action to be done while updating the load average
*/
#define UPDATE_TG 0x1
#define SKIP_AGE_LOAD 0x2

/* Update task and its cfs_rq load average */
static inline void update_load_avg(struct sched_entity *se, int update_tg)
static inline void update_load_avg(struct sched_entity *se, int flags)
{
struct cfs_rq *cfs_rq = cfs_rq_of(se);
u64 now = cfs_rq_clock_task(cfs_rq);
Expand All @@ -3104,11 +3110,13 @@ static inline void update_load_avg(struct sched_entity *se, int update_tg)
* Track task load average for carrying it to new CPU after migrated, and
* track group sched_entity load average for task_h_load calc in migration
*/
__update_load_avg(now, cpu, &se->avg,
if (se->avg.last_update_time && !(flags & SKIP_AGE_LOAD)) {
__update_load_avg(now, cpu, &se->avg,
se->on_rq * scale_load_down(se->load.weight),
cfs_rq->curr == se, NULL);
}

if (update_cfs_rq_load_avg(now, cfs_rq, true) && update_tg)
if (update_cfs_rq_load_avg(now, cfs_rq, true) && (flags & UPDATE_TG))
update_tg_load_avg(cfs_rq, 0);
}

Expand All @@ -3122,26 +3130,6 @@ static inline void update_load_avg(struct sched_entity *se, int update_tg)
*/
static void attach_entity_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se)
{
if (!sched_feat(ATTACH_AGE_LOAD))
goto skip_aging;

/*
* If we got migrated (either between CPUs or between cgroups) we'll
* have aged the average right before clearing @last_update_time.
*
* Or we're fresh through post_init_entity_util_avg().
*/
if (se->avg.last_update_time) {
__update_load_avg(cfs_rq->avg.last_update_time, cpu_of(rq_of(cfs_rq)),
&se->avg, 0, 0, NULL);

/*
* XXX: we could have just aged the entire load away if we've been
* absent from the fair class for too long.
*/
}

skip_aging:
se->avg.last_update_time = cfs_rq->avg.last_update_time;
cfs_rq->avg.load_avg += se->avg.load_avg;
cfs_rq->avg.load_sum += se->avg.load_sum;
Expand All @@ -3161,9 +3149,6 @@ static void attach_entity_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *s
*/
static void detach_entity_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se)
{
__update_load_avg(cfs_rq->avg.last_update_time, cpu_of(rq_of(cfs_rq)),
&se->avg, se->on_rq * scale_load_down(se->load.weight),
cfs_rq->curr == se, NULL);

sub_positive(&cfs_rq->avg.load_avg, se->avg.load_avg);
sub_positive(&cfs_rq->avg.load_sum, se->avg.load_sum);
Expand All @@ -3178,34 +3163,20 @@ static inline void
enqueue_entity_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se)
{
struct sched_avg *sa = &se->avg;
u64 now = cfs_rq_clock_task(cfs_rq);
int migrated, decayed;

migrated = !sa->last_update_time;
if (!migrated) {
__update_load_avg(now, cpu_of(rq_of(cfs_rq)), sa,
se->on_rq * scale_load_down(se->load.weight),
cfs_rq->curr == se, NULL);
}

decayed = update_cfs_rq_load_avg(now, cfs_rq, !migrated);

cfs_rq->runnable_load_avg += sa->load_avg;
cfs_rq->runnable_load_sum += sa->load_sum;

if (migrated)
if (!sa->last_update_time) {
attach_entity_load_avg(cfs_rq, se);

if (decayed || migrated)
update_tg_load_avg(cfs_rq, 0);
}
}

/* Remove the runnable load generated by se from cfs_rq's runnable load average */
static inline void
dequeue_entity_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se)
{
update_load_avg(se, 1);

cfs_rq->runnable_load_avg =
max_t(long, cfs_rq->runnable_load_avg - se->avg.load_avg, 0);
cfs_rq->runnable_load_sum =
Expand Down Expand Up @@ -3289,7 +3260,10 @@ update_cfs_rq_load_avg(u64 now, struct cfs_rq *cfs_rq, bool update_freq)
return 0;
}

static inline void update_load_avg(struct sched_entity *se, int not_used)
#define UPDATE_TG 0x0
#define SKIP_AGE_LOAD 0x0

static inline void update_load_avg(struct sched_entity *se, int not_used1)
{
cpufreq_update_util(rq_of(cfs_rq_of(se)), 0);
}
Expand Down Expand Up @@ -3434,6 +3408,7 @@ enqueue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags)
if (renorm && !curr)
se->vruntime += cfs_rq->min_vruntime;

update_load_avg(se, UPDATE_TG);
enqueue_entity_load_avg(cfs_rq, se);
account_entity_enqueue(cfs_rq, se);
update_cfs_shares(cfs_rq);
Expand Down Expand Up @@ -3508,6 +3483,7 @@ 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_load_avg(se, UPDATE_TG);
dequeue_entity_load_avg(cfs_rq, se);

update_stats_dequeue(cfs_rq, se, flags);
Expand Down Expand Up @@ -3595,7 +3571,7 @@ 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_load_avg(se, 1);
update_load_avg(se, UPDATE_TG);
}

update_stats_curr_start(cfs_rq, se);
Expand Down Expand Up @@ -3713,7 +3689,7 @@ entity_tick(struct cfs_rq *cfs_rq, struct sched_entity *curr, int queued)
/*
* Ensure that runnable average is periodically updated.
*/
update_load_avg(curr, 1);
update_load_avg(curr, UPDATE_TG);
update_cfs_shares(cfs_rq);

#ifdef CONFIG_SCHED_HRTICK
Expand Down Expand Up @@ -4610,7 +4586,7 @@ enqueue_task_fair(struct rq *rq, struct task_struct *p, int flags)
if (cfs_rq_throttled(cfs_rq))
break;

update_load_avg(se, 1);
update_load_avg(se, UPDATE_TG);
update_cfs_shares(cfs_rq);
}

Expand Down Expand Up @@ -4669,7 +4645,7 @@ static void dequeue_task_fair(struct rq *rq, struct task_struct *p, int flags)
if (cfs_rq_throttled(cfs_rq))
break;

update_load_avg(se, 1);
update_load_avg(se, UPDATE_TG);
update_cfs_shares(cfs_rq);
}

Expand Down Expand Up @@ -8821,18 +8797,16 @@ static inline bool vruntime_normalized(struct task_struct *p)
static void detach_entity_cfs_rq(struct sched_entity *se)
{
struct cfs_rq *cfs_rq = cfs_rq_of(se);
u64 now = cfs_rq_clock_task(cfs_rq);

/* Catch up with the cfs_rq and remove our load when we leave */
update_cfs_rq_load_avg(now, cfs_rq, false);
update_load_avg(se, 0);
detach_entity_load_avg(cfs_rq, se);
update_tg_load_avg(cfs_rq, false);
}

static void attach_entity_cfs_rq(struct sched_entity *se)
{
struct cfs_rq *cfs_rq = cfs_rq_of(se);
u64 now = cfs_rq_clock_task(cfs_rq);

#ifdef CONFIG_FAIR_GROUP_SCHED
/*
Expand All @@ -8843,7 +8817,7 @@ static void attach_entity_cfs_rq(struct sched_entity *se)
#endif

/* Synchronize entity with its cfs_rq */
update_cfs_rq_load_avg(now, cfs_rq, false);
update_load_avg(se, sched_feat(ATTACH_AGE_LOAD) ? 0 : SKIP_AGE_LOAD);
attach_entity_load_avg(cfs_rq, se);
update_tg_load_avg(cfs_rq, false);
}
Expand Down

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