attach_entity_load_avg() is called (indirectly) from:
- switched_to_fair(): switch between classes to fair
- task_move_group_fair(): move between task groups
- enqueue_entity_load_avg(): enqueue entity
Only in switched_to_fair() is it possible that the task's last_update_time
is not 0 and therefore the task needs sched avgs update, so move the task
sched avgs update to switched_to_fair() only. In addition, code comments are
clarified.
No functionality change.
Signed-off-by: Yuyang Du <yuyang...@intel.com>
---
kernel/sched/fair.c | 39 +++++++++++++++++++++------------------
1 file changed, 21 insertions(+), 18 deletions(-)
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 218f8e8..e89c39b 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -2961,24 +2961,6 @@ static inline void update_load_avg(struct sched_entity
*se, int update_tg)
static void attach_entity_load_avg(struct cfs_rq *cfs_rq, struct sched_entity
*se)
{
- if (!sched_feat(ATTACH_AGE_LOAD))
- goto skip_aging;
-
- /*
- * If we got migrated (either between CPUs or between cgroups) we'll
- * have aged the average right before clearing @last_update_time.
- */
- if (se->avg.last_update_time) {
- __update_load_avg(cfs_rq->avg.last_update_time,
cpu_of(rq_of(cfs_rq)),
- &se->avg, 0, 0, NULL);
-
- /*
- * XXX: we could have just aged the entire load away if we've
been
- * absent from the fair class for too long.
- */
- }
-
-skip_aging:
se->avg.last_update_time = cfs_rq->avg.last_update_time;
cfs_rq->avg.load_avg += se->avg.load_avg;
cfs_rq->avg.load_sum += se->avg.load_sum;
@@ -8418,6 +8400,27 @@ static void switched_from_fair(struct rq *rq, struct
task_struct *p)
static void switched_to_fair(struct rq *rq, struct task_struct *p)
{
+#ifdef CONFIG_SMP
+ struct sched_entity *se = &p->se;
+
+ if (!sched_feat(ATTACH_AGE_LOAD))
+ goto skip_aging;
+
+ /*
+ * If we change between classes, age the averages before attaching them.
+ */
+ if (se->avg.last_update_time) {
+ __update_load_avg(cfs_rq_of(se)->avg.last_update_time,
cpu_of(rq),
+ &se->avg, 0, 0, NULL);
+
+ /*
+ * XXX: we could have just aged the entire load away if we've
been
+ * absent from the fair class for too long.
+ */
+ }
+
+skip_aging:
+#endif
attach_task_cfs_rq(p);
if (task_on_rq_queued(p)) {
--
1.7.9.5
