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Groups > linux.kernel > #1406991

[PATCH v2] sched: fix first task of a task group is attached twice

From Vincent Guittot <vincent.guittot@linaro.org>
Newsgroups linux.kernel
Subject [PATCH v2] sched: fix first task of a task group is attached twice
Date 2016-05-25 17:10 +0200
Message-ID <rCIBz-2uj-19@gated-at.bofh.it> (permalink)
References <rCkfT-3Ft-9@gated-at.bofh.it>
Organization linux.* mail to news gateway

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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>
---

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

 kernel/sched/fair.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 218f8e8..3724656 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -8586,6 +8586,14 @@ void init_tg_cfs_entry(struct task_group *tg, struct cfs_rq *cfs_rq,
 		se->depth = parent->depth + 1;
 	}
 
+	/*
+	 * 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.
+	 */
+	tg->cfs_rq[cpu]->avg.last_update_time = 1;
+
 	se->my_q = cfs_rq;
 	/* guarantee group entities always have weight */
 	update_load_set(&se->load, NICE_0_LOAD);
-- 
1.9.1

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Thread

[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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