linux-kernel - [PATCH v2 06/10] sched/fair: delete superfluous SKIP_AGE

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Date:   Wed, 13 Jul 2022 12:04:26 +0800
From:   Chengming Zhou <zhouchengming@...edance.com>
To:     mingo@...hat.com, peterz@...radead.org, vincent.guittot@...aro.org,
        dietmar.eggemann@....com, rostedt@...dmis.org, bsegall@...gle.com,
        vschneid@...hat.com
Cc:     linux-kernel@...r.kernel.org,
        Chengming Zhou <zhouchengming@...edance.com>
Subject: [PATCH v2 06/10] sched/fair: delete superfluous SKIP_AGE_LOAD

There are three types of attach_entity_cfs_rq():

1. task migrate to CPU
2. task move to cgroup
3. task switched to fair from !fair

The case1 and case2 already have sched_avg last_update_time
reset to 0 when attach_entity_cfs_rq().

We will make case3 also have last_update_time reset to 0 when
attach_entity_cfs_rq() in the following patches.

So it makes no difference whether SKIP_AGE_LOAD is set or not.

Signed-off-by: Chengming Zhou <zhouchengming@...edance.com>
---
 kernel/sched/fair.c | 10 ++++------
 1 file changed, 4 insertions(+), 6 deletions(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 171bc22bc142..29811869c1fe 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -4001,9 +4001,8 @@ static void detach_entity_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *s
  * Optional action to be done while updating the load average
  */
 #define UPDATE_TG	0x1
-#define SKIP_AGE_LOAD	0x2
-#define DO_ATTACH	0x4
-#define DO_DETACH	0x8
+#define DO_ATTACH	0x2
+#define DO_DETACH	0x4
 
 /* Update task and its cfs_rq load average */
 static inline void update_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags)
@@ -4015,7 +4014,7 @@ static inline void update_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *s
 	 * Track task load average for carrying it to new CPU after migrated, and
 	 * track group sched_entity load average for task_h_load calc in migration
 	 */
-	if (se->avg.last_update_time && !(flags & SKIP_AGE_LOAD))
+	if (se->avg.last_update_time)
 		__update_load_avg_se(now, cfs_rq, se);
 
 	decayed  = update_cfs_rq_load_avg(now, cfs_rq);
@@ -4298,7 +4297,6 @@ static inline bool cfs_rq_is_decayed(struct cfs_rq *cfs_rq)
 }
 
 #define UPDATE_TG	0x0
-#define SKIP_AGE_LOAD	0x0
 #define DO_ATTACH	0x0
 #define DO_DETACH	0x0
 
@@ -11540,7 +11538,7 @@ static void attach_entity_cfs_rq(struct sched_entity *se)
 	struct cfs_rq *cfs_rq = cfs_rq_of(se);
 
 	/* Synchronize entity with its cfs_rq */
-	update_load_avg(cfs_rq, se, sched_feat(ATTACH_AGE_LOAD) ? 0 : SKIP_AGE_LOAD);
+	update_load_avg(cfs_rq, se, 0);
 	attach_entity_load_avg(cfs_rq, se);
 	update_tg_load_avg(cfs_rq);
 	propagate_entity_cfs_rq(se);
-- 
2.36.1