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sched/fair: Move enqueue migrate handling 

Move the entity migrate handling from enqueue_entity_load_avg() to
update_load_avg(). This has two benefits:

 - {en,de}queue_entity_load_avg() will become purely about managing
   runnable_load

 - we can avoid a double update_tg_load_avg() and reduce pressure on
   the global tg->shares cacheline

The reason we do this is so that we can change update_cfs_shares() to
change both weight and (future) runnable_weight. For this to work we
need to have the cfs_rq averages up-to-date (which means having done
the attach), but we need the cfs_rq->avg.runnable_avg to not yet
include the se's contribution (since se->on_rq == 0).

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 17:37:03 +02:00 committed by Ingo Molnar
parent 88c0616ee7
commit b382a531b9
1 changed files with 36 additions and 34 deletions
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70
kernel/sched/fair.c
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@ -3473,34 +3473,6 @@ update_cfs_rq_load_avg(u64 now, struct cfs_rq *cfs_rq)
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 cfs_rq *cfs_rq, struct sched_entity *se, int flags)
{
u64 now = cfs_rq_clock_task(cfs_rq);
struct rq *rq = rq_of(cfs_rq);
int cpu = cpu_of(rq);
int decayed;
/*
* 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
*/
if (se->avg.last_update_time && !(flags & SKIP_AGE_LOAD))
__update_load_avg_se(now, cpu, cfs_rq, se);
decayed = update_cfs_rq_load_avg(now, cfs_rq);
decayed |= propagate_entity_load_avg(se);
if (decayed && (flags & UPDATE_TG))
update_tg_load_avg(cfs_rq, 0);
}
/**
* attach_entity_load_avg - attach this entity to its cfs_rq load avg
* @cfs_rq: cfs_rq to attach to
@ -3541,17 +3513,46 @@ static void detach_entity_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *s
cfs_rq_util_change(cfs_rq);
}
/*
* Optional action to be done while updating the load average
*/
#define UPDATE_TG 0x1
#define SKIP_AGE_LOAD 0x2
#define DO_ATTACH 0x4
/* Update task and its cfs_rq load average */
static inline void update_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags)
{
u64 now = cfs_rq_clock_task(cfs_rq);
struct rq *rq = rq_of(cfs_rq);
int cpu = cpu_of(rq);
int decayed;
/*
* 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
*/
if (se->avg.last_update_time && !(flags & SKIP_AGE_LOAD))
__update_load_avg_se(now, cpu, cfs_rq, se);
decayed = update_cfs_rq_load_avg(now, cfs_rq);
decayed |= propagate_entity_load_avg(se);
if (!se->avg.last_update_time && (flags & DO_ATTACH)) {
attach_entity_load_avg(cfs_rq, se);
update_tg_load_avg(cfs_rq, 0);
} else if (decayed && (flags & UPDATE_TG))
update_tg_load_avg(cfs_rq, 0);
}
/* Add the load generated by se into cfs_rq's load average */
static inline void
enqueue_entity_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;
if (!se->avg.last_update_time) {
attach_entity_load_avg(cfs_rq, se);
update_tg_load_avg(cfs_rq, 0);
}
}
/* Remove the runnable load generated by se from cfs_rq's runnable load average */
@ -3641,6 +3642,7 @@ update_cfs_rq_load_avg(u64 now, struct cfs_rq *cfs_rq)
#define UPDATE_TG 0x0
#define SKIP_AGE_LOAD 0x0
#define DO_ATTACH 0x0
static inline void update_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se, int not_used1)
{
@ -3795,7 +3797,7 @@ enqueue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags)
* its group cfs_rq
* - Add its new weight to cfs_rq->load.weight
*/
update_load_avg(cfs_rq, se, UPDATE_TG);
update_load_avg(cfs_rq, se, UPDATE_TG | DO_ATTACH);
enqueue_entity_load_avg(cfs_rq, se);
update_cfs_shares(se);
account_entity_enqueue(cfs_rq, se);