Commit 75381608 authored Nov 26, 2014 by Wanpeng Li Committed by Ingo Molnar Feb 04, 2015

sched/deadline: Avoid pointless __setscheduler()



There is no need to dequeue/enqueue and push/pull if there are
no scheduling parameters changed for the DL class.

Both fair and RT classes already check if parameters changed for
them to avoid unnecessary overhead. This patch add the parameters
changed test for the DL class in order to reduce overhead.

Signed-off-by: Wanpeng Li <wanpeng.li@linux.intel.com>
[ Fixed up the changelog. ]
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Juri Lelli <juri.lelli@arm.com>
Cc: Kirill Tkhai <ktkhai@parallels.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/1416962647-76792-5-git-send-email-wanpeng.li@linux.intel.com


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

parent 1019a359

kernel/sched/core.c

+15 −1

Original line number	Diff line number	Diff line
		@@ -3417,6 +3417,20 @@ static bool check_same_owner(struct task_struct *p)
		return match;
		}

		static bool dl_param_changed(struct task_struct *p,
		const struct sched_attr *attr)
		{
		struct sched_dl_entity *dl_se = &p->dl;

		if (dl_se->dl_runtime != attr->sched_runtime \|\|
		dl_se->dl_deadline != attr->sched_deadline \|\|
		dl_se->dl_period != attr->sched_period \|\|
		dl_se->flags != attr->sched_flags)
		return true;

		return false;
		}

		static int __sched_setscheduler(struct task_struct *p,
		const struct sched_attr *attr,
		bool user)
		@@ -3545,7 +3559,7 @@ recheck:
		goto change;
		if (rt_policy(policy) && attr->sched_priority != p->rt_priority)
		goto change;
		if (dl_policy(policy))
		if (dl_policy(policy) && dl_param_changed(p, attr))
		goto change;

		p->sched_reset_on_fork = reset_on_fork;

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