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Date: Thu, 13 Aug 2015 19:49:19 +0900
From: byungchul.park@....com
To: mingo@...nel.org, peterz@...radead.org
Cc: linux-kernel@...r.kernel.org, yuyang.du@...el.com,
Byungchul Park <byungchul.park@....com>
Subject: [PATCH 2/2] sched: make task_move_group_fair simple by using switched_to(from)_fair
From: Byungchul Park <byungchul.park@....com>
i introduced need_vruntime_adjust() to check if do or not adjust vruntime
when attaching/detaching a se to/from its cfs_rq, and use it.
i made the best use of switched_to(from)_fair for attach(detach)
operations in task_move_group_fair().
Signed-off-by: Byungchul Park <byungchul.park@....com>
---
kernel/sched/fair.c | 80 +++++++++++++++++++--------------------------------
1 file changed, 29 insertions(+), 51 deletions(-)
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index d91e4da..5ec846f 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -7904,6 +7904,31 @@ prio_changed_fair(struct rq *rq, struct task_struct *p, int oldprio)
check_preempt_curr(rq, p, 0);
}
+static inline int need_vruntime_adjust(struct task_struct *p, int queued)
+{
+ struct sched_entity *se = &p->se;
+
+ /*
+ * When !queued, vruntime of the task has usually NOT been normalized.
+ * But there are some cases where it has already been normalized:
+ *
+ * - Moving a forked child which is waiting for being woken up by
+ * wake_up_new_task().
+ * - Moving a task which has been woken up by try_to_wake_up() and
+ * waiting for actually being woken up by sched_ttwu_pending().
+ */
+ if (queued)
+ return 0;
+
+ if (!se->sum_exec_runtime || p->state == TASK_WAKING)
+ return 0;
+
+ if (p->state != TASK_RUNNING)
+ return 1;
+
+ return 0;
+}
+
static void switched_from_fair(struct rq *rq, struct task_struct *p)
{
struct sched_entity *se = &p->se;
@@ -7918,7 +7943,7 @@ static void switched_from_fair(struct rq *rq, struct task_struct *p)
* have normalized the vruntime, if it's !queued, then only when
* the task is sleeping will it still have non-normalized vruntime.
*/
- if (!task_on_rq_queued(p) && p->state != TASK_RUNNING) {
+ if (need_vruntime_adjust(p, task_on_rq_queued(p))) {
/*
* Fix up our vruntime so that the current sleep doesn't
* cause 'unlimited' sleep bonus.
@@ -7939,7 +7964,6 @@ static void switched_from_fair(struct rq *rq, struct task_struct *p)
static void switched_to_fair(struct rq *rq, struct task_struct *p)
{
struct sched_entity *se = &p->se;
-
#ifdef CONFIG_FAIR_GROUP_SCHED
/*
* Since the real-depth could have been changed (only FAIR
@@ -7964,7 +7988,7 @@ static void switched_to_fair(struct rq *rq, struct task_struct *p)
* has non-normalized vruntime, if it's !queued, then it still has
* normalized vruntime.
*/
- if (p->state != TASK_RUNNING)
+ if (need_vruntime_adjust(p, task_on_rq_queued(p)))
se->vruntime += cfs_rq_of(se)->min_vruntime;
return;
}
@@ -8014,55 +8038,9 @@ void init_cfs_rq(struct cfs_rq *cfs_rq)
#ifdef CONFIG_FAIR_GROUP_SCHED
static void task_move_group_fair(struct task_struct *p, int queued)
{
- struct sched_entity *se = &p->se;
- struct cfs_rq *cfs_rq;
-
- /*
- * If the task was not on the rq at the time of this cgroup movement
- * it must have been asleep, sleeping tasks keep their ->vruntime
- * absolute on their old rq until wakeup (needed for the fair sleeper
- * bonus in place_entity()).
- *
- * If it was on the rq, we've just 'preempted' it, which does convert
- * ->vruntime to a relative base.
- *
- * Make sure both cases convert their relative position when migrating
- * to another cgroup's rq. This does somewhat interfere with the
- * fair sleeper stuff for the first placement, but who cares.
- */
- /*
- * When !queued, vruntime of the task has usually NOT been normalized.
- * But there are some cases where it has already been normalized:
- *
- * - Moving a forked child which is waiting for being woken up by
- * wake_up_new_task().
- * - Moving a task which has been woken up by try_to_wake_up() and
- * waiting for actually being woken up by sched_ttwu_pending().
- *
- * To prevent boost or penalty in the new cfs_rq caused by delta
- * min_vruntime between the two cfs_rqs, we skip vruntime adjustment.
- */
- if (!queued && (!se->sum_exec_runtime || p->state == TASK_WAKING))
- queued = 1;
-
- cfs_rq = cfs_rq_of(se);
- if (!queued)
- se->vruntime -= cfs_rq->min_vruntime;
-
-#ifdef CONFIG_SMP
- /* synchronize task with its prev cfs_rq */
- detach_entity_load_avg(cfs_rq, se);
-#endif
+ switched_from_fair(task_rq(p), p);
set_task_rq(p, task_cpu(p));
- se->depth = se->parent ? se->parent->depth + 1 : 0;
- cfs_rq = cfs_rq_of(se);
- if (!queued)
- se->vruntime += cfs_rq->min_vruntime;
-
-#ifdef CONFIG_SMP
- /* Virtually synchronize task with its new cfs_rq */
- attach_entity_load_avg(cfs_rq, se);
-#endif
+ switched_to_fair(task_rq(p), p);
}
void free_fair_sched_group(struct task_group *tg)
--
1.7.9.5
--
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