[tip:sched/core] sched/deadline: Add rq-> clock update skip for dl task yield

[tip-bot for Wanpeng Li <tipbot@zytor.com>]

Commit-ID:  44fb085bfa17628c6d2aaa6af6b292a8499e9cbd
Gitweb:     http://git.kernel.org/tip/44fb085bfa17628c6d2aaa6af6b292a8499e9cbd
Author:     Wanpeng Li <wanpeng.li@linux.intel.com>
AuthorDate: Tue, 10 Mar 2015 12:20:00 +0800
Committer:  Ingo Molnar <mingo@kernel.org>
CommitDate: Tue, 10 Mar 2015 05:46:50 +0100

sched/deadline: Add rq->clock update skip for dl task yield

This patch adds rq->clock update skip for SCHED_DEADLINE task yield,
to tell update_rq_clock() that we've just updated the clock, so that
we don't do a microscopic update in schedule() and double the
fastpath cost.

Signed-off-by: Wanpeng Li <wanpeng.li@linux.intel.com>
Cc: Juri Lelli <juri.lelli@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1425961200-3809-1-git-send-email-wanpeng.li@linux.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
 kernel/sched/deadline.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c
index 3fa8fa6..0a81a95 100644
--- a/kernel/sched/deadline.c
+++ b/kernel/sched/deadline.c
@@ -914,6 +914,12 @@ static void yield_task_dl(struct rq *rq)
 	}
 	update_rq_clock(rq);
 	update_curr_dl(rq);
+	/*
+	 * Tell update_rq_clock() that we've just updated,
+	 * so we don't do microscopic update in schedule()
+	 * and double the fastpath cost.
+	 */
+	rq_clock_skip_update(rq, true);
 }
 
 #ifdef CONFIG_SMP