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Subject[PATCH] sched: fix lose fair sleeper bonus in switch_to_fair()
Date
The sleeper task will be normalized when moved from fair_sched_class, in 
order that vruntime will be adjusted either the task is running or sleeping
when moved back. The nomalization in switch_to_fair for sleep task will
result in lose fair sleeper bonus in place_entity() once the vruntime -
cfs_rq->min_vruntime is big when moved from fair_sched_class.

This patch fix it by adjusting vruntime just during migrating as original
codes since the vruntime of the task has usually NOT been normalized in
this case.

Signed-off-by: Wanpeng Li <wanpeng.li@hotmail.com>
---
kernel/sched/fair.c | 11 +++++++----
1 files changed, 7 insertions(+), 4 deletions(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index d26d3b7..eb9aa35 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -8005,9 +8005,6 @@ static void attach_task_cfs_rq(struct task_struct *p)

/* Synchronize task with its cfs_rq */
attach_entity_load_avg(cfs_rq, se);
-
- if (!vruntime_normalized(p))
- se->vruntime += cfs_rq->min_vruntime;
}

static void switched_from_fair(struct rq *rq, struct task_struct *p)
@@ -8066,14 +8063,20 @@ void init_cfs_rq(struct cfs_rq *cfs_rq)
#ifdef CONFIG_FAIR_GROUP_SCHED
static void task_move_group_fair(struct task_struct *p)
{
+ struct sched_entity *se = &p->se;
+ struct cfs_rq *cfs_rq = cfs_rq_of(se);
+
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;
+ se->avg.last_update_time = 0;
#endif
attach_task_cfs_rq(p);
+
+ if (!vruntime_normalized(p))
+ se->vruntime += cfs_rq->min_vruntime;
}

void free_fair_sched_group(struct task_group *tg)
--
1.7.1


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