Commit bb04159d authored Dec 15, 2014 by Kirill Tkhai Committed by Ingo Molnar Jan 14, 2015

sched/fair: Fix sched_entity::avg::decay_count initialization



Child has the same decay_count as parent. If it's not zero,
we add it to parent's cfs_rq->removed_load:

wake_up_new_task()->set_task_cpu()->migrate_task_rq_fair().

Child's load is a just garbade after copying of parent,
it hasn't been on cfs_rq yet, and it must not be added to
cfs_rq::removed_load in migrate_task_rq_fair().

The patch moves sched_entity::avg::decay_count intialization
in sched_fork(). So, migrate_task_rq_fair() does not change
removed_load.

Signed-off-by: Kirill Tkhai <ktkhai@parallels.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Ben Segall <bsegall@google.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/1418644618.6074.13.camel@tkhai


Signed-off-by: Ingo Molnar <mingo@kernel.org>

parent 1f8a7633

kernel/sched/core.c

+3 −0

Original line number	Diff line number	Diff line
		@@ -1832,6 +1832,9 @@ static void __sched_fork(unsigned long clone_flags, struct task_struct *p)
		p->se.prev_sum_exec_runtime = 0;
		p->se.nr_migrations = 0;
		p->se.vruntime = 0;
		#ifdef CONFIG_SMP
		p->se.avg.decay_count = 0;
		#endif
		INIT_LIST_HEAD(&p->se.group_node);

		#ifdef CONFIG_SCHEDSTATS

kernel/sched/fair.c

+0 −1

Original line number	Diff line number	Diff line
		@@ -676,7 +676,6 @@ void init_task_runnable_average(struct task_struct *p)
		{
		u32 slice;

		p->se.avg.decay_count = 0;
		slice = sched_slice(task_cfs_rq(p), &p->se) >> 10;
		p->se.avg.runnable_avg_sum = slice;
		p->se.avg.runnable_avg_period = slice;

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