[PATCH] sched: sync with the cfs_rq when changing sched class

[Byungchul Park]

currently, a task load is synced with its cfs_rq, only when it
leaves from fair class. we also need to sync it with cfs_rq when
it returns back to fair class, too.

in addition, i created two functions for attaching/detaching a se
load from/to its cfs_rq, and let them use those functions. and i
place that function call to where a se is attached/detached
to/from cfs_rq.

Signed-off-by: Byungchul Park <byungchul.park@xxxxxxx>
---
 kernel/sched/fair.c |   78 +++++++++++++++++++++++++--------------------------
 1 file changed, 39 insertions(+), 39 deletions(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 979ca2c..72d13af 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -2709,6 +2709,31 @@ static inline void update_load_avg(struct sched_entity *se, int update_tg)
 		update_tg_load_avg(cfs_rq, 0);
 }
 
+static void attach_entity_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se)
+{
+	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;
+	cfs_rq->avg.util_avg += se->avg.util_avg;
+	cfs_rq->avg.util_sum += se->avg.util_sum;
+}
+
+static void detach_entity_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se)
+{
+	__update_load_avg(cfs_rq->avg.last_update_time, cpu_of(rq_of(cfs_rq)),
+			&se->avg, se->on_rq * scale_load_down(se->load.weight),
+			cfs_rq->curr == se, NULL);
+
+	cfs_rq->avg.load_avg =
+		max_t(long, cfs_rq->avg.load_avg - se->avg.load_avg, 0);
+	cfs_rq->avg.load_sum =
+		max_t(s64, cfs_rq->avg.load_sum - se->avg.load_sum, 0);
+	cfs_rq->avg.util_avg =
+		max_t(long, cfs_rq->avg.util_avg - se->avg.util_avg, 0);
+	cfs_rq->avg.util_sum =
+		max_t(s32, cfs_rq->avg.util_sum - se->avg.util_sum, 0);
+}
+
 /* Add the load generated by se into cfs_rq's load average */
 static inline void
 enqueue_entity_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se)
@@ -2717,27 +2742,20 @@ enqueue_entity_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se)
 	u64 now = cfs_rq_clock_task(cfs_rq);
 	int migrated = 0, decayed;
 
-	if (sa->last_update_time == 0) {
-		sa->last_update_time = now;
+	if (sa->last_update_time == 0)
 		migrated = 1;
-	}
-	else {
+	else
 		__update_load_avg(now, cpu_of(rq_of(cfs_rq)), sa,
-			se->on_rq * scale_load_down(se->load.weight),
-			cfs_rq->curr == se, NULL);
-	}
+				se->on_rq * scale_load_down(se->load.weight),
+				cfs_rq->curr == se, NULL);
 
 	decayed = update_cfs_rq_load_avg(now, cfs_rq);
 
 	cfs_rq->runnable_load_avg += sa->load_avg;
 	cfs_rq->runnable_load_sum += sa->load_sum;
 
-	if (migrated) {
-		cfs_rq->avg.load_avg += sa->load_avg;
-		cfs_rq->avg.load_sum += sa->load_sum;
-		cfs_rq->avg.util_avg += sa->util_avg;
-		cfs_rq->avg.util_sum += sa->util_sum;
-	}
+	if (migrated)
+		attach_entity_load_avg(cfs_rq, se);
 
 	if (decayed || migrated)
 		update_tg_load_avg(cfs_rq, 0);
@@ -7911,17 +7929,7 @@ static void switched_from_fair(struct rq *rq, struct task_struct *p)
 
 #ifdef CONFIG_SMP
 	/* Catch up with the cfs_rq and remove our load when we leave */
-	__update_load_avg(cfs_rq->avg.last_update_time, cpu_of(rq), &se->avg,
-		se->on_rq * scale_load_down(se->load.weight), cfs_rq->curr == se, NULL);
-
-	cfs_rq->avg.load_avg =
-		max_t(long, cfs_rq->avg.load_avg - se->avg.load_avg, 0);
-	cfs_rq->avg.load_sum =
-		max_t(s64, cfs_rq->avg.load_sum - se->avg.load_sum, 0);
-	cfs_rq->avg.util_avg =
-		max_t(long, cfs_rq->avg.util_avg - se->avg.util_avg, 0);
-	cfs_rq->avg.util_sum =
-		max_t(s32, cfs_rq->avg.util_sum - se->avg.util_sum, 0);
+	detach_entity_load_avg(cfs_rq, se);
 #endif
 }
 
@@ -7938,6 +7946,11 @@ static void switched_to_fair(struct rq *rq, struct task_struct *p)
 	 */
 	se->depth = se->parent ? se->parent->depth + 1 : 0;
 #endif
+
+#ifdef CONFIG_SMP
+	/* synchronize task with its cfs_rq */
+	attach_entity_load_avg(cfs_rq_of(&p->se), &p->se);
+#endif
 	if (!task_on_rq_queued(p))
 		return;
 
@@ -8023,16 +8036,7 @@ static void task_move_group_fair(struct task_struct *p, int queued)
 
 #ifdef CONFIG_SMP
 	/* synchronize task with its prev cfs_rq */
-	if (!queued)
-		__update_load_avg(cfs_rq->avg.last_update_time, cpu_of(rq_of(cfs_rq)),
-				&se->avg, se->on_rq * scale_load_down(se->load.weight),
-				cfs_rq->curr == se, NULL);
-
-	/* remove our load when we leave */
-	cfs_rq->avg.load_avg = max_t(long, cfs_rq->avg.load_avg - se->avg.load_avg, 0);
-	cfs_rq->avg.load_sum = max_t(s64, cfs_rq->avg.load_sum - se->avg.load_sum, 0);
-	cfs_rq->avg.util_avg = max_t(long, cfs_rq->avg.util_avg - se->avg.util_avg, 0);
-	cfs_rq->avg.util_sum = max_t(s32, cfs_rq->avg.util_sum - se->avg.util_sum, 0);
+	detach_entity_load_avg(cfs_rq, se);
 #endif
 	set_task_rq(p, task_cpu(p));
 	se->depth = se->parent ? se->parent->depth + 1 : 0;
@@ -8042,11 +8046,7 @@ static void task_move_group_fair(struct task_struct *p, int queued)
 
 #ifdef CONFIG_SMP
 	/* Virtually synchronize task with its new cfs_rq */
-	p->se.avg.last_update_time = cfs_rq->avg.last_update_time;
-	cfs_rq->avg.load_avg += p->se.avg.load_avg;
-	cfs_rq->avg.load_sum += p->se.avg.load_sum;
-	cfs_rq->avg.util_avg += p->se.avg.util_avg;
-	cfs_rq->avg.util_sum += p->se.avg.util_sum;
+	attach_entity_load_avg(cfs_rq, se);
 #endif
 }
 
-- 
1.7.9.5

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