[PATCH v3 4/5] sched/fair: Move load and util avgs from wake_up_new_task() to sched_fork()

[Yuyang Du]

Move new task initialization to sched_fork(). For initial non-fair class
task, the first switched_to_fair() will do the attach correctly.

Suggested-by: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Signed-off-by: Yuyang Du <yuyang.du@xxxxxxxxx>
---
 kernel/sched/core.c  |    5 +++--
 kernel/sched/fair.c  |   14 +++++---------
 kernel/sched/sched.h |    2 +-
 3 files changed, 9 insertions(+), 12 deletions(-)

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index ae5b8a8..77a8a2b 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -2370,6 +2370,9 @@ int sched_fork(unsigned long clone_flags, struct task_struct *p)
 	if (p->sched_class->task_fork)
 		p->sched_class->task_fork(p);
 
+	/* Initialize new task's sched averages */
+	init_entity_sched_avg(&p->se);
+
 	/*
 	 * The child is not yet in the pid-hash so no cgroup attach races,
 	 * and the cgroup is pinned to this child due to cgroup_fork()
@@ -2510,8 +2513,6 @@ void wake_up_new_task(struct task_struct *p)
 	struct rq_flags rf;
 	struct rq *rq;
 
-	/* Initialize new task's runnable average */
-	init_entity_runnable_average(&p->se);
 	raw_spin_lock_irqsave(&p->pi_lock, rf.flags);
 #ifdef CONFIG_SMP
 	/*
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 0b4914d..eb9041c 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -668,8 +668,8 @@ static unsigned long task_h_load(struct task_struct *p);
 #define LOAD_AVG_MAX 47742 /* maximum possible load avg */
 #define LOAD_AVG_MAX_N 345 /* number of full periods to produce LOAD_AVG_MAX */
 
-/* Give new sched_entity start runnable values to heavy its load in infant time */
-void init_entity_runnable_average(struct sched_entity *se)
+/* Give new sched_entity start load values to heavy its load in infant time */
+void init_entity_sched_avg(struct sched_entity *se)
 {
 	struct sched_avg *sa = &se->avg;
 
@@ -738,12 +738,8 @@ void post_init_entity_util_avg(struct sched_entity *se)
 static inline unsigned long cfs_rq_runnable_load_avg(struct cfs_rq *cfs_rq);
 static inline unsigned long cfs_rq_load_avg(struct cfs_rq *cfs_rq);
 #else
-void init_entity_runnable_average(struct sched_entity *se)
-{
-}
-void post_init_entity_util_avg(struct sched_entity *se)
-{
-}
+void init_entity_sched_avg(struct sched_entity *se) { }
+void post_init_entity_util_avg(struct sched_entity *se) { }
 #endif
 
 /*
@@ -8520,7 +8516,7 @@ int alloc_fair_sched_group(struct task_group *tg, struct task_group *parent)
 
 		init_cfs_rq(cfs_rq);
 		init_tg_cfs_entry(tg, cfs_rq, se, i, parent->se[i]);
-		init_entity_runnable_average(se);
+		init_entity_sched_avg(se);
 		post_init_entity_util_avg(se);
 	}
 
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index c139ec4..bc9c99e 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -1321,7 +1321,7 @@ extern void init_dl_task_timer(struct sched_dl_entity *dl_se);
 
 unsigned long to_ratio(u64 period, u64 runtime);
 
-extern void init_entity_runnable_average(struct sched_entity *se);
+extern void init_entity_sched_avg(struct sched_entity *se);
 extern void post_init_entity_util_avg(struct sched_entity *se);
 
 #ifdef CONFIG_NO_HZ_FULL
-- 
1.7.9.5