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Date: Mon, 1 Aug 2022 12:27:43 +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 v3 08/10] sched/fair: refactor detach/attach_entity_cfs_rq using update_load_avg()
Since update_load_avg() now support DO_ATTACH and DO_DETACH flags to
attach or detach entity sched_avg to the cfs_rq, we can using it to
refactor detach/attach_entity_cfs_rq() functions.
Note we can attach a task with last_update_time!=0 from switched_to_fair()
since we want to decay sched_avg when running in !fair class.
So this patch move last_update_time condition check to enqueue_entity()
for task which migrate CPU or change cgroup.
Signed-off-by: Chengming Zhou <zhouchengming@...edance.com>
---
kernel/sched/fair.c | 68 ++++++++++++++++++---------------------------
1 file changed, 27 insertions(+), 41 deletions(-)
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index ad20a939227d..b8cb826bd755 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -4019,21 +4019,10 @@ static inline void update_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *s
decayed = update_cfs_rq_load_avg(now, cfs_rq);
decayed |= propagate_entity_load_avg(se);
- if (!se->avg.last_update_time && (flags & DO_ATTACH)) {
- /*
- * DO_ATTACH means we're here from enqueue_entity().
- * !last_update_time means we've passed through
- * migrate_task_rq_fair() indicating we migrated.
- *
- * IOW we're enqueueing a task on a new CPU.
- */
+ if (flags & DO_ATTACH) {
attach_entity_load_avg(cfs_rq, se);
update_tg_load_avg(cfs_rq);
} else if (flags & DO_DETACH) {
- /*
- * DO_DETACH means we're here from dequeue_entity()
- * and we are migrating task out of the CPU.
- */
detach_entity_load_avg(cfs_rq, se);
update_tg_load_avg(cfs_rq);
} else if (decayed) {
@@ -4082,44 +4071,31 @@ static void remove_entity_load_avg(struct sched_entity *se)
raw_spin_unlock_irqrestore(&cfs_rq->removed.lock, flags);
}
-#ifdef CONFIG_FAIR_GROUP_SCHED
/*
* Propagate the changes of the sched_entity across the tg tree to make it
* visible to the root
*/
-static void propagate_entity_cfs_rq(struct sched_entity *se)
+static void propagate_entity_cfs_rq(struct sched_entity *se, int flags)
{
- struct cfs_rq *cfs_rq = cfs_rq_of(se);
-
- if (cfs_rq_throttled(cfs_rq))
- return;
-
- if (!throttled_hierarchy(cfs_rq))
- list_add_leaf_cfs_rq(cfs_rq);
-
- /* Start to propagate at parent */
- se = se->parent;
+ struct cfs_rq *cfs_rq;
for_each_sched_entity(se) {
cfs_rq = cfs_rq_of(se);
- update_load_avg(cfs_rq, se, UPDATE_TG);
+ update_load_avg(cfs_rq, se, flags);
if (cfs_rq_throttled(cfs_rq))
break;
if (!throttled_hierarchy(cfs_rq))
list_add_leaf_cfs_rq(cfs_rq);
+
+ flags = UPDATE_TG;
}
}
-#else
-static void propagate_entity_cfs_rq(struct sched_entity *se) { }
-#endif
static void detach_entity_cfs_rq(struct sched_entity *se)
{
- struct cfs_rq *cfs_rq = cfs_rq_of(se);
-
/*
* In case the task sched_avg hasn't been attached:
* - A forked task which hasn't been woken up by wake_up_new_task().
@@ -4130,21 +4106,18 @@ static void detach_entity_cfs_rq(struct sched_entity *se)
return;
/* Catch up with the cfs_rq and remove our load when we leave */
- update_load_avg(cfs_rq, se, 0);
- detach_entity_load_avg(cfs_rq, se);
- update_tg_load_avg(cfs_rq);
- propagate_entity_cfs_rq(se);
+ propagate_entity_cfs_rq(se, DO_DETACH | UPDATE_TG);
}
static void attach_entity_cfs_rq(struct sched_entity *se)
{
- struct cfs_rq *cfs_rq = cfs_rq_of(se);
+ int flags = DO_ATTACH | UPDATE_TG;
+
+ if (!sched_feat(ATTACH_AGE_LOAD))
+ flags |= SKIP_AGE_LOAD;
- /* Synchronize entity with its cfs_rq */
- update_load_avg(cfs_rq, se, sched_feat(ATTACH_AGE_LOAD) ? 0 : SKIP_AGE_LOAD);
- attach_entity_load_avg(cfs_rq, se);
- update_tg_load_avg(cfs_rq);
- propagate_entity_cfs_rq(se);
+ /* Synchronize entity with its cfs_rq and attach our load */
+ propagate_entity_cfs_rq(se, flags);
}
static inline unsigned long cfs_rq_runnable_avg(struct cfs_rq *cfs_rq)
@@ -4479,6 +4452,15 @@ enqueue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags)
{
bool renorm = !(flags & ENQUEUE_WAKEUP) || (flags & ENQUEUE_MIGRATED);
bool curr = cfs_rq->curr == se;
+ int action = UPDATE_TG;
+
+ /*
+ * !last_update_time means we've passed through migrate_task_rq_fair()
+ * or task_change_group_fair() indicating we migrated cfs_rq. IOW we're
+ * enqueueing a task on a new CPU or moving task to a new cgroup.
+ */
+ if (!se->avg.last_update_time)
+ action |= DO_ATTACH;
/*
* If we're the current task, we must renormalise before calling
@@ -4507,7 +4489,7 @@ enqueue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags)
* its group cfs_rq
* - Add its new weight to cfs_rq->load.weight
*/
- update_load_avg(cfs_rq, se, UPDATE_TG | DO_ATTACH);
+ update_load_avg(cfs_rq, se, action);
se_update_runnable(se);
update_cfs_group(se);
account_entity_enqueue(cfs_rq, se);
@@ -4581,6 +4563,10 @@ dequeue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags)
{
int action = UPDATE_TG;
+ /*
+ * When we are migrating task out of the CPU, we should
+ * detach entity sched_avg from the cfs_rq.
+ */
if (entity_is_task(se) && task_on_rq_migrating(task_of(se)))
action |= DO_DETACH;
--
2.36.1
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