tick: Dynamically set broadcast irq affinity
When a cpu goes to a deep idle state where its local timer is
shutdown, it notifies the time frame work to use the broadcast timer
instead. Unfortunately, the broadcast device could wake up any CPU,
including an idle one which is not concerned by the wake up at all. So
in the worst case an idle CPU will wake up to send an IPI to the CPU
whose timer expired.
Provide an opt-in feature CLOCK_EVT_FEAT_DYNIRQ which tells the core
that is should set the interrupt affinity of the broadcast interrupt
to the cpu which has the earliest expiry time. This avoids unnecessary
spurious wakeups and IPIs.
[ tglx: Adopted to cpumask rework, silenced an uninitialized warning,
massaged changelog ]
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: viresh.kumar@linaro.org
Cc: jacob.jun.pan@linux.intel.com
Cc: linux-arm-kernel@lists.infradead.org
Cc: santosh.shilimkar@ti.com
Cc: linaro-kernel@lists.linaro.org
Cc: patches@linaro.org
Cc: rickard.andersson@stericsson.com
Cc: vincent.guittot@linaro.org
Cc: linus.walleij@stericsson.com
Cc: john.stultz@linaro.org
Link: http://lkml.kernel.org/r/1362219013-18173-3-git-send-email-daniel.lezcano@linaro.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
diff --git a/include/linux/clockchips.h b/include/linux/clockchips.h
index 6634652..494d33e 100644
--- a/include/linux/clockchips.h
+++ b/include/linux/clockchips.h
@@ -55,6 +55,11 @@
#define CLOCK_EVT_FEAT_C3STOP 0x000008
#define CLOCK_EVT_FEAT_DUMMY 0x000010
+/*
+ * Core shall set the interrupt affinity dynamically in broadcast mode
+ */
+#define CLOCK_EVT_FEAT_DYNIRQ 0x000020
+
/**
* struct clock_event_device - clock event device descriptor
* @event_handler: Assigned by the framework to be called by the low