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sched/fair: Remove redundant call to cpufreq_update_util()

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  bef69dd878 ("sched/cpufreq: Move the cfs_rq_util_change() call to cpufreq_update_util()")

update_load_avg() has become the central point for calling cpufreq
(not including the update of blocked load). This change helps to
simplify further the number of calls to cpufreq_update_util() and to
remove last redundant ones. With update_load_avg(), we are now sure
that cpufreq_update_util() will be called after every task attachment
to a cfs_rq and especially after propagating this event down to the
util_avg of the root cfs_rq, which is the level that is used by
cpufreq governors like schedutil to set the frequency of a CPU.

The SCHED_CPUFREQ_MIGRATION flag forces an early call to cpufreq when
the migration happens in a cgroup whereas util_avg of root cfs_rq is
not yet updated and this call is duplicated with the one that happens
immediately after when the migration event reaches the root cfs_rq.
The dedicated flag SCHED_CPUFREQ_MIGRATION is now useless and can be
removed. The interface of attach_entity_load_avg() can also be
simplified accordingly.

Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Link: https://lkml.kernel.org/r/1579083620-24943-1-git-send-email-vincent.guittot@linaro.org
This commit is contained in:
Vincent Guittot 2020-01-15 11:20:20 +01:00 committed by Peter Zijlstra
parent 3d817689a6
commit a4f9a0e51b
2 changed files with 7 additions and 8 deletions
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1
include/linux/sched/cpufreq.h
View File

@ -9,7 +9,6 @@
*/
#define SCHED_CPUFREQ_IOWAIT (1U << 0)
#define SCHED_CPUFREQ_MIGRATION (1U << 1)
#ifdef CONFIG_CPU_FREQ
struct cpufreq_policy;

14
kernel/sched/fair.c
View File

@ -801,7 +801,7 @@ void post_init_entity_util_avg(struct task_struct *p)
* For !fair tasks do:
*
update_cfs_rq_load_avg(now, cfs_rq);
attach_entity_load_avg(cfs_rq, se, 0);
attach_entity_load_avg(cfs_rq, se);
switched_from_fair(rq, p);
*
* such that the next switched_to_fair() has the
@ -3114,7 +3114,7 @@ static inline void cfs_rq_util_change(struct cfs_rq *cfs_rq, int flags)
{
struct rq *rq = rq_of(cfs_rq);
if (&rq->cfs == cfs_rq || (flags & SCHED_CPUFREQ_MIGRATION)) {
if (&rq->cfs == cfs_rq) {
/*
* There are a few boundary cases this might miss but it should
* get called often enough that that should (hopefully) not be
@ -3521,7 +3521,7 @@ update_cfs_rq_load_avg(u64 now, struct cfs_rq *cfs_rq)
* Must call update_cfs_rq_load_avg() before this, since we rely on
* cfs_rq->avg.last_update_time being current.
*/
static void attach_entity_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags)
static void attach_entity_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se)
{
u32 divider = LOAD_AVG_MAX - 1024 + cfs_rq->avg.period_contrib;
@ -3557,7 +3557,7 @@ static void attach_entity_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *s
add_tg_cfs_propagate(cfs_rq, se->avg.load_sum);
cfs_rq_util_change(cfs_rq, flags);
cfs_rq_util_change(cfs_rq, 0);
trace_pelt_cfs_tp(cfs_rq);
}
@ -3615,7 +3615,7 @@ static inline void update_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *s
*
* IOW we're enqueueing a task on a new CPU.
*/
attach_entity_load_avg(cfs_rq, se, SCHED_CPUFREQ_MIGRATION);
attach_entity_load_avg(cfs_rq, se);
update_tg_load_avg(cfs_rq, 0);
} else if (decayed) {
@ -3872,7 +3872,7 @@ static inline void update_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *s
static inline void remove_entity_load_avg(struct sched_entity *se) {}
static inline void
attach_entity_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags) {}
attach_entity_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se) {}
static inline void
detach_entity_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se) {}
@ -10436,7 +10436,7 @@ static void attach_entity_cfs_rq(struct sched_entity *se)
/* Synchronize entity with its cfs_rq */
update_load_avg(cfs_rq, se, sched_feat(ATTACH_AGE_LOAD) ? 0 : SKIP_AGE_LOAD);
attach_entity_load_avg(cfs_rq, se, 0);
attach_entity_load_avg(cfs_rq, se);
update_tg_load_avg(cfs_rq, false);
propagate_entity_cfs_rq(se);
}