Merge branch 'timers.2014.02.25a' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu into timers/core
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
diff --git a/kernel/time/Kconfig b/kernel/time/Kconfig
index 3ce6e8c..f448513 100644
--- a/kernel/time/Kconfig
+++ b/kernel/time/Kconfig
@@ -124,7 +124,7 @@
endchoice
config NO_HZ_FULL_ALL
- bool "Full dynticks system on all CPUs by default"
+ bool "Full dynticks system on all CPUs by default (except CPU 0)"
depends on NO_HZ_FULL
help
If the user doesn't pass the nohz_full boot option to
diff --git a/kernel/timer.c b/kernel/timer.c
index c0d8898..a71bdfd 100644
--- a/kernel/timer.c
+++ b/kernel/timer.c
@@ -960,8 +960,15 @@
* with the timer by holding the timer base lock. This also
* makes sure that a CPU on the way to stop its tick can not
* evaluate the timer wheel.
+ *
+ * Spare the IPI for deferrable timers on idle targets though.
+ * The next busy ticks will take care of it. Except full dynticks
+ * require special care against races with idle_cpu(), lets deal
+ * with that later.
*/
- wake_up_nohz_cpu(cpu);
+ if (!tbase_get_deferrable(timer->base) || tick_nohz_full_cpu(cpu))
+ wake_up_nohz_cpu(cpu);
+
spin_unlock_irqrestore(&base->lock, flags);
}
EXPORT_SYMBOL_GPL(add_timer_on);