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Subject[tip:sched/core] sched/fair: Simplify post_init_entity_util_avg() by calling it with a task_struct pointer argument
Commit-ID:  d0fe0b9c45c144e4ac60cf7f07f7e8ae86d3536d
Gitweb: https://git.kernel.org/tip/d0fe0b9c45c144e4ac60cf7f07f7e8ae86d3536d
Author: Dietmar Eggemann <dietmar.eggemann@arm.com>
AuthorDate: Tue, 22 Jan 2019 16:25:01 +0000
Committer: Ingo Molnar <mingo@kernel.org>
CommitDate: Mon, 11 Feb 2019 08:02:14 +0100

sched/fair: Simplify post_init_entity_util_avg() by calling it with a task_struct pointer argument

Since commit:

d03266910a53 ("sched/fair: Fix task group initialization")

the utilization of a sched entity representing a task group is no longer
initialized to any other value than 0. So post_init_entity_util_avg() is
only used for tasks, not for sched_entities.

Make this clear by calling it with a task_struct pointer argument which
also eliminates the entity_is_task(se) if condition in the fork path and
get rid of the stale comment in remove_entity_load_avg() accordingly.

Signed-off-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Morten Rasmussen <morten.rasmussen@arm.com>
Cc: Patrick Bellasi <patrick.bellasi@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Quentin Perret <quentin.perret@arm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Valentin Schneider <valentin.schneider@arm.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Link: https://lkml.kernel.org/r/20190122162501.12000-1-dietmar.eggemann@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
kernel/sched/core.c | 2 +-
kernel/sched/fair.c | 38 ++++++++++++++++----------------------
kernel/sched/sched.h | 2 +-
3 files changed, 18 insertions(+), 24 deletions(-)

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index e86e2b8f6922..6b2c055564b5 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -2433,7 +2433,7 @@ void wake_up_new_task(struct task_struct *p)
#endif
rq = __task_rq_lock(p, &rf);
update_rq_clock(rq);
- post_init_entity_util_avg(&p->se);
+ post_init_entity_util_avg(p);

activate_task(rq, p, ENQUEUE_NOCLOCK);
p->on_rq = TASK_ON_RQ_QUEUED;
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 17a961522d1e..58edbbdeb661 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -759,8 +759,9 @@ static void attach_entity_cfs_rq(struct sched_entity *se);
* Finally, that extrapolated util_avg is clamped to the cap (util_avg_cap)
* if util_avg > util_avg_cap.
*/
-void post_init_entity_util_avg(struct sched_entity *se)
+void post_init_entity_util_avg(struct task_struct *p)
{
+ struct sched_entity *se = &p->se;
struct cfs_rq *cfs_rq = cfs_rq_of(se);
struct sched_avg *sa = &se->avg;
long cpu_scale = arch_scale_cpu_capacity(NULL, cpu_of(rq_of(cfs_rq)));
@@ -778,22 +779,19 @@ void post_init_entity_util_avg(struct sched_entity *se)
}
}

- if (entity_is_task(se)) {
- struct task_struct *p = task_of(se);
- if (p->sched_class != &fair_sched_class) {
- /*
- * For !fair tasks do:
- *
- update_cfs_rq_load_avg(now, cfs_rq);
- attach_entity_load_avg(cfs_rq, se, 0);
- switched_from_fair(rq, p);
- *
- * such that the next switched_to_fair() has the
- * expected state.
- */
- se->avg.last_update_time = cfs_rq_clock_pelt(cfs_rq);
- return;
- }
+ if (p->sched_class != &fair_sched_class) {
+ /*
+ * For !fair tasks do:
+ *
+ update_cfs_rq_load_avg(now, cfs_rq);
+ attach_entity_load_avg(cfs_rq, se, 0);
+ switched_from_fair(rq, p);
+ *
+ * such that the next switched_to_fair() has the
+ * expected state.
+ */
+ se->avg.last_update_time = cfs_rq_clock_pelt(cfs_rq);
+ return;
}

attach_entity_cfs_rq(se);
@@ -803,7 +801,7 @@ void post_init_entity_util_avg(struct sched_entity *se)
void init_entity_runnable_average(struct sched_entity *se)
{
}
-void post_init_entity_util_avg(struct sched_entity *se)
+void post_init_entity_util_avg(struct task_struct *p)
{
}
static void update_tg_load_avg(struct cfs_rq *cfs_rq, int force)
@@ -3590,10 +3588,6 @@ void remove_entity_load_avg(struct sched_entity *se)
* tasks cannot exit without having gone through wake_up_new_task() ->
* post_init_entity_util_avg() which will have added things to the
* cfs_rq, so we can remove unconditionally.
- *
- * Similarly for groups, they will have passed through
- * post_init_entity_util_avg() before unregister_sched_fair_group()
- * calls this.
*/

sync_entity_load_avg(se);
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index c688ef5012e5..71208b67e58a 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -1800,7 +1800,7 @@ extern void init_dl_rq_bw_ratio(struct dl_rq *dl_rq);
unsigned long to_ratio(u64 period, u64 runtime);

extern void init_entity_runnable_average(struct sched_entity *se);
-extern void post_init_entity_util_avg(struct sched_entity *se);
+extern void post_init_entity_util_avg(struct task_struct *p);

#ifdef CONFIG_NO_HZ_FULL
extern bool sched_can_stop_tick(struct rq *rq);
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