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Groups > linux.kernel > #1409250

[PATCH v3] sched: fix first task of a task group is attached twice

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The cfs_rq->avg.last_update_time is initialize to 0 with the main effect
that the 1st sched_entity that will be attached, will keep its
last_update_time set to 0 and will attached once again during the
enqueue.
Initialize cfs_rq->avg.last_update_time to 1 instead.

Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
---

v3:
- add initialization of load_last_update_time_copy for not 64bits system
- move init into init_cfs_rq

v2:
- rq_clock_task(rq_of(cfs_rq)) can't be used because lock is not held

 kernel/sched/fair.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 218f8e8..86be9c1 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -8459,6 +8459,16 @@ void init_cfs_rq(struct cfs_rq *cfs_rq)
 	cfs_rq->min_vruntime_copy = cfs_rq->min_vruntime;
 #endif
 #ifdef CONFIG_SMP
+	/*
+	 * Set last_update_time to something different from 0 to make
+	 * sure the 1st sched_entity will not be attached twice: once
+	 * when attaching the task to the group and one more time when
+	 * enqueueing the task.
+	 */
+	cfs_rq->avg.last_update_time = 1;
+#ifndef CONFIG_64BIT
+	cfs_rq->load_last_update_time_copy = 1;
+#endif
 	atomic_long_set(&cfs_rq->removed_load_avg, 0);
 	atomic_long_set(&cfs_rq->removed_util_avg, 0);
 #endif
-- 
1.9.1

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[PATCH] sched: fix first task of a task group is attached twice Vincent Guittot <vincent.guittot@linaro.org> - 2016-05-24 15:10 +0200
  [PATCH v2] sched: fix first task of a task group is attached twice Vincent Guittot <vincent.guittot@linaro.org> - 2016-05-25 17:10 +0200
    Re: [PATCH v2] sched: fix first task of a task group is attached  twice Yuyang Du <yuyang.du@intel.com> - 2016-05-26 08:40 +0200
      Re: [PATCH v2] sched: fix first task of a task group is attached twice Vincent Guittot <vincent.guittot@linaro.org> - 2016-05-26 10:30 +0200
        Re: [PATCH v2] sched: fix first task of a task group is attached  twice Yuyang Du <yuyang.du@intel.com> - 2016-05-26 10:40 +0200
          Re: [PATCH v2] sched: fix first task of a task group is attached twice Vincent Guittot <vincent.guittot@linaro.org> - 2016-05-26 11:00 +0200
    Re: [PATCH v2] sched: fix first task of a task group is attached  twice Dietmar Eggemann <dietmar.eggemann@arm.com> - 2016-05-27 17:50 +0200
      Re: [PATCH v2] sched: fix first task of a task group is attached twice Vincent Guittot <vincent.guittot@linaro.org> - 2016-05-27 19:20 +0200
        Re: [PATCH v2] sched: fix first task of a task group is attached  twice Dietmar Eggemann <dietmar.eggemann@arm.com> - 2016-05-27 22:40 +0200
          Re: [PATCH v2] sched: fix first task of a task group is attached twice Vincent Guittot <vincent.guittot@linaro.org> - 2016-05-30 09:10 +0200
            [PATCH v3] sched: fix first task of a task group is attached twice Vincent Guittot <vincent.guittot@linaro.org> - 2016-05-30 18:00 +0200
              Re: [PATCH v3] sched: fix first task of a task group is attached  twice Yuyang Du <yuyang.du@intel.com> - 2016-05-31 05:50 +0200
                Re: [PATCH v3] sched: fix first task of a task group is attached twice Vincent Guittot <vincent.guittot@linaro.org> - 2016-05-31 09:30 +0200
                Re: [PATCH v3] sched: fix first task of a task group is attached  twice Yuyang Du <yuyang.du@intel.com> - 2016-05-31 10:50 +0200
          Re: [PATCH v2] sched: fix first task of a task group is attached twice Vincent Guittot <vincent.guittot@linaro.org> - 2016-05-30 18:00 +0200

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