[PATCH v5 3/9] sched/fair: reset sched_avg last_update_time before set_task_rq()

From: Chengming Zhou
Date: Wed Aug 17 2022 - 23:46:00 EST


set_task_rq() -> set_task_rq_fair() will try to synchronize the blocked
task's sched_avg when migrate, which is not needed for already detached
task.

task_change_group_fair() will detached the task sched_avg from prev cfs_rq
first, so reset sched_avg last_update_time before set_task_rq() to avoid that.

Signed-off-by: Chengming Zhou <zhouchengming@xxxxxxxxxxxxx>
Reviewed-by: Dietmar Eggemann <dietmar.eggemann@xxxxxxx>
Reviewed-by: Vincent Guittot <vincent.guittot@xxxxxxxxxx>
---
kernel/sched/fair.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 4b95599aa951..5a704109472a 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -11824,12 +11824,12 @@ void init_cfs_rq(struct cfs_rq *cfs_rq)
static void task_change_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
+ set_task_rq(p, task_cpu(p));
attach_task_cfs_rq(p);
}

--
2.37.2