[PATCH] tick-management: broadcast functionality
With Ingo Molnar <mingo@elte.hu>
Add broadcast functionality, so per cpu clock event devices can be registered
as dummy devices or switched from/to broadcast on demand. The broadcast
function distributes the events via the broadcast function of the clock event
device. This is primarily designed to replace the switch apic timer to / from
IPI in power states, where the apic stops.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Cc: john stultz <johnstul@us.ibm.com>
Cc: Roman Zippel <zippel@linux-m68k.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/kernel/time/tick-common.c b/kernel/time/tick-common.c
index 46e4381..48167a6 100644
--- a/kernel/time/tick-common.c
+++ b/kernel/time/tick-common.c
@@ -20,17 +20,19 @@
#include <linux/sched.h>
#include <linux/tick.h>
+#include "tick-internal.h"
+
/*
* Tick devices
*/
-static DEFINE_PER_CPU(struct tick_device, tick_cpu_device);
+DEFINE_PER_CPU(struct tick_device, tick_cpu_device);
/*
* Tick next event: keeps track of the tick time
*/
-static ktime_t tick_next_period;
-static ktime_t tick_period;
+ktime_t tick_next_period;
+ktime_t tick_period;
static int tick_do_timer_cpu = -1;
-static DEFINE_SPINLOCK(tick_device_lock);
+DEFINE_SPINLOCK(tick_device_lock);
/*
* Periodic tick
@@ -78,9 +80,13 @@
/*
* Setup the device for a periodic tick
*/
-void tick_setup_periodic(struct clock_event_device *dev)
+void tick_setup_periodic(struct clock_event_device *dev, int broadcast)
{
- dev->event_handler = tick_handle_periodic;
+ tick_set_periodic_handler(dev, broadcast);
+
+ /* Broadcast setup ? */
+ if (!tick_device_is_functional(dev))
+ return;
if (dev->features & CLOCK_EVT_FEAT_PERIODIC) {
clockevents_set_mode(dev, CLOCK_EVT_MODE_PERIODIC);
@@ -145,6 +151,15 @@
if (!cpus_equal(newdev->cpumask, cpumask))
irq_set_affinity(newdev->irq, cpumask);
+ /*
+ * When global broadcasting is active, check if the current
+ * device is registered as a placeholder for broadcast mode.
+ * This allows us to handle this x86 misfeature in a generic
+ * way.
+ */
+ if (tick_device_uses_broadcast(newdev, cpu))
+ return;
+
if (td->mode == TICKDEV_MODE_PERIODIC)
tick_setup_periodic(newdev, 0);
}
@@ -197,19 +212,33 @@
* Check the rating
*/
if (curdev->rating >= newdev->rating)
- goto out;
+ goto out_bc;
}
/*
* Replace the eventually existing device by the new
- * device.
+ * device. If the current device is the broadcast device, do
+ * not give it back to the clockevents layer !
*/
+ if (tick_is_broadcast_device(curdev)) {
+ clockevents_set_mode(curdev, CLOCK_EVT_MODE_SHUTDOWN);
+ curdev = NULL;
+ }
clockevents_exchange_device(curdev, newdev);
tick_setup_device(td, newdev, cpu, cpumask);
- ret = NOTIFY_STOP;
+ spin_unlock_irqrestore(&tick_device_lock, flags);
+ return NOTIFY_STOP;
+
+out_bc:
+ /*
+ * Can the new device be used as a broadcast device ?
+ */
+ if (tick_check_broadcast_device(newdev))
+ ret = NOTIFY_STOP;
out:
spin_unlock_irqrestore(&tick_device_lock, flags);
+
return ret;
}
@@ -251,7 +280,13 @@
case CLOCK_EVT_NOTIFY_ADD:
return tick_check_new_device(dev);
+ case CLOCK_EVT_NOTIFY_BROADCAST_ON:
+ case CLOCK_EVT_NOTIFY_BROADCAST_OFF:
+ tick_broadcast_on_off(reason, dev);
+ break;
+
case CLOCK_EVT_NOTIFY_CPU_DEAD:
+ tick_shutdown_broadcast(dev);
tick_shutdown(dev);
break;