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From: Yuyang Du <yuyang.du@intel.com>
To: peterz@infradead.org, mingo@kernel.org, linux-kernel@vger.kernel.org
Cc: bsegall@google.com, pjt@google.com, morten.rasmussen@arm.com,
	vincent.guittot@linaro.org, dietmar.eggemann@arm.com,
	matt@codeblueprint.co.uk, Yuyang Du <yuyang.du@intel.com>
Subject: [PATCH v5 1/5] sched/fair: Clean up attach_entity_load_avg()
Date: Thu,  9 Jun 2016 07:15:50 +0800	[thread overview]
Message-ID: <1465427754-28897-2-git-send-email-yuyang.du@intel.com> (raw)
In-Reply-To: <1465427754-28897-1-git-send-email-yuyang.du@intel.com>

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, the code is
refactored and code comments are updated.

No functionality change.

Signed-off-by: Yuyang Du <yuyang.du@intel.com>
---
 kernel/sched/fair.c |   43 ++++++++++++++++++++-----------------------
 1 file changed, 20 insertions(+), 23 deletions(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index c6dd8ba..34e658b 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -2935,24 +2935,6 @@ 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;
@@ -2962,6 +2944,19 @@ skip_aging:
 	cfs_rq_util_change(cfs_rq);
 }
 
+static inline void attach_age_load_task(struct rq *rq, struct task_struct *p)
+{
+	struct sched_entity *se = &p->se;
+
+	if (!sched_feat(ATTACH_AGE_LOAD))
+		return;
+
+	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);
+	}
+}
+
 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)),
@@ -3091,6 +3086,7 @@ static inline void
 attach_entity_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se) {}
 static inline void
 detach_entity_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se) {}
+static inline void attach_age_load_task(struct rq *rq, struct task_struct *p) {}
 
 static inline int idle_balance(struct rq *rq)
 {
@@ -8390,6 +8386,12 @@ static void switched_from_fair(struct rq *rq, struct task_struct *p)
 
 static void switched_to_fair(struct rq *rq, struct task_struct *p)
 {
+	/*
+	 * If we change between classes, age the averages before attaching them.
+	 * XXX: we could have just aged the entire load away if we've been
+	 * absent from the fair class for too long.
+	 */
+	attach_age_load_task(rq, p);
 	attach_task_cfs_rq(p);
 
 	if (task_on_rq_queued(p)) {
@@ -8441,11 +8443,6 @@ static void task_move_group_fair(struct task_struct *p)
 {
 	detach_task_cfs_rq(p);
 	set_task_rq(p, task_cpu(p));
-
-#ifdef CONFIG_SMP
-	/* Tell se's cfs_rq has been changed -- migrated */
-	p->se.avg.last_update_time = 0;
-#endif
 	attach_task_cfs_rq(p);
 }
 
-- 
1.7.9.5

  reply	other threads:[~2016-06-09  7:13 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-06-08 23:15 [PATCH v5 0/5] sched/fair: Fix attach and detach sched avgs for task group change and sched class change Yuyang Du
2016-06-08 23:15 ` Yuyang Du [this message]
2016-06-14 11:11   ` [PATCH v5 1/5] sched/fair: Clean up attach_entity_load_avg() Matt Fleming
2016-06-14 12:11     ` Peter Zijlstra
2016-06-14 22:18     ` Yuyang Du
2016-06-08 23:15 ` [PATCH v5 2/5] sched/fair: Fix attaching task sched avgs twice when switching to fair or changing task group Yuyang Du
2016-06-08 23:15 ` [PATCH v5 3/5] sched/fair: Move load and util avgs from wake_up_new_task() to sched_fork() Yuyang Du
2016-06-08 23:15 ` [PATCH v5 4/5] sched/fair: Skip detach sched avgs for new task when changing task groups Yuyang Du
2016-06-14 11:38   ` Matt Fleming
2016-06-14 14:36   ` Peter Zijlstra
2016-06-14 14:45     ` Peter Zijlstra
2016-06-08 23:15 ` [PATCH v5 5/5] sched/fair: Add inline to detach_entity_load_evg() Yuyang Du

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