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 5bbb1044f8473ff98bd3fdfe2c93a1c0798ed8e7..342fc9ccab46d5132aae1c58b1fbce0d02a2feaf 100644 (file)
--- 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