From: Thomas Gleixner <tglx@linutronix.de>
Date: Mon, 10 Nov 2008 12:20:23 +0000 (+0100)
Subject: nohz: disable tick_nohz_kick_tick() for now
X-Git-Tag: v2.6.28-rc5~78^2~1
X-Git-Url: http://pilppa.com/gitweb/?a=commitdiff_plain;h=ae99286b4f1be7788f2d6947c66a91dbd6351eec;p=linux-2.6-omap-h63xx.git

nohz: disable tick_nohz_kick_tick() for now

Impact: nohz powersavings and wakeup regression

commit fb02fbc14d17837b4b7b02dbb36142c16a7bf208 (NOHZ: restart tick
device from irq_enter()) causes a serious wakeup regression.

While the patch is correct it does not take into account that spurious
wakeups happen on x86. A fix for this issue is available, but we just
revert to the .27 behaviour and let long running softirqs screw
themself.

Disable it for now.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---

diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
index 5bbb1044f84..342fc9ccab4 100644
--- a/kernel/time/tick-sched.c
+++ b/kernel/time/tick-sched.c
@@ -568,6 +568,9 @@ static void tick_nohz_switch_to_nohz(void)
  */
 static void tick_nohz_kick_tick(int cpu)
 {
+#if 0
+	/* Switch back to 2.6.27 behaviour */
+
 	struct tick_sched *ts = &per_cpu(tick_cpu_sched, cpu);
 	ktime_t delta, now;
 
@@ -584,6 +587,7 @@ static void tick_nohz_kick_tick(int cpu)
 		return;
 
 	tick_nohz_restart(ts, now);
+#endif
 }
 
 #else