From 35af99e646c7f7ea46dc2977601e9e71a51dadd5 Mon Sep 17 00:00:00 2001
From: Peter Zijlstra <peterz@infradead.org>
Date: Thu, 28 Nov 2013 19:38:42 +0100
Subject: sched/clock, x86: Use a static_key for sched_clock_stable
In order to avoid the runtime condition and variable load turn
sched_clock_stable into a static_key.
Also provide a shorter implementation of local_clock() and
cpu_clock(int) when sched_clock_stable==1.
MAINLINE PRE POST
sched_clock_stable: 1 1 1
(cold) sched_clock: 329841 221876 215295
(cold) local_clock: 301773 234692 220773
(warm) sched_clock: 38375 25602 25659
(warm) local_clock: 100371 33265 27242
(warm) rdtsc: 27340 24214 24208
sched_clock_stable: 0 0 0
(cold) sched_clock: 382634 235941 237019
(cold) local_clock: 396890 297017 294819
(warm) sched_clock: 38194 25233 25609
(warm) local_clock: 143452 71234 71232
(warm) rdtsc: 27345 24245 24243
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Link: http://lkml.kernel.org/n/tip-eummbdechzz37mwmpags1gjr@git.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
kernel/time/tick-sched.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
(limited to 'kernel/time/tick-sched.c')
diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
index ea20f7d1ac2..c833249ab0f 100644
--- a/kernel/time/tick-sched.c
+++ b/kernel/time/tick-sched.c
@@ -177,7 +177,7 @@ static bool can_stop_full_tick(void)
* TODO: kick full dynticks CPUs when
* sched_clock_stable is set.
*/
- if (!sched_clock_stable) {
+ if (!sched_clock_stable()) {
trace_tick_stop(0, "unstable sched clock\n");
/*
* Don't allow the user to think they can get
--
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