From: Chris Wright <chrisw@sous-sol.org>

Add tick_nohz_{stop,restart}_sched_tick to idle loop in prepartion for turning
on dynticks.  These are just noops until NO_HZ is enabled.

Signed-off-by: Chris Wright <chrisw@sous-sol.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Cc: Andi Kleen <ak@suse.de>
Cc: john stultz <johnstul@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 arch/x86_64/kernel/process.c |    6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff -puN arch/x86_64/kernel/process.c~x86_64-prep-idle-loop-for-dynticks arch/x86_64/kernel/process.c
--- a/arch/x86_64/kernel/process.c~x86_64-prep-idle-loop-for-dynticks
+++ a/arch/x86_64/kernel/process.c
@@ -38,6 +38,7 @@
 #include <linux/notifier.h>
 #include <linux/kprobes.h>
 #include <linux/kdebug.h>
+#include <linux/tick.h>
 
 #include <asm/uaccess.h>
 #include <asm/pgtable.h>
@@ -197,7 +198,7 @@ static inline void play_dead(void)
  * low exit latency (ie sit in a loop waiting for
  * somebody to say that they'd like to reschedule)
  */
-void cpu_idle (void)
+void cpu_idle(void)
 {
 	current_thread_info()->status |= TS_POLLING;
 	/* endless idle loop with no priority at all */
@@ -208,6 +209,8 @@ void cpu_idle (void)
 			if (__get_cpu_var(cpu_idle_state))
 				__get_cpu_var(cpu_idle_state) = 0;
 
+			tick_nohz_stop_sched_tick();
+
 			rmb();
 			idle = pm_idle;
 			if (!idle)
@@ -228,6 +231,7 @@ void cpu_idle (void)
 			__exit_idle();
 		}
 
+		tick_nohz_restart_sched_tick();
 		preempt_enable_no_resched();
 		schedule();
 		preempt_disable();
_