[PATCH v5 3/5] sched/fair: Move load and util avgs from wake_up_new_task() to sched_fork()

From: Yuyang Du
Date: Thu Jun 09 2016 - 03:13:24 EST


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 7f2cae4..5d72567 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 68fcd2e..6e870c6 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

/*
@@ -8514,7 +8510,7 @@ 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 72f1f30..6087950 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