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Subject[PATCH 1/7] ICH Force HPET: Make generic time capable of switching broadcast timer


Auto-detect the presence of HPET on ICH5 or newer platforms and enable
HPET for broadcast timer. This gives a bigger upperlimit for tickless time
tick and improves the power consumption in comparison to PIT as broadcast timer.

This patch:

Change the broadcast timer, if a timer with higher rating becomes available.

Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>

---

Applies over linux-2.6.22-rc4-mm2 +
tglx's patch-2.6.22-rc4-mm2-hrt4 patch

The patchset had been baking for a while along with patch-2.6.22-rc*-hrt* for
a while without breaking anything and redusing the number of
timer interrupts with tickless on various platforms.

kernel/time/tick-broadcast.c | 13 ++++++-------
kernel/time/tick-common.c | 4 ++--
2 files changed, 8 insertions(+), 9 deletions(-)

Index: linux-2.6.22-rc5/kernel/time/tick-common.c
===================================================================
--- linux-2.6.22-rc5.orig/kernel/time/tick-common.c 2007-06-17 08:52:07.000000000 +0200
+++ linux-2.6.22-rc5/kernel/time/tick-common.c 2007-06-17 08:52:10.000000000 +0200
@@ -200,7 +200,7 @@ static int tick_check_new_device(struct

cpu = smp_processor_id();
if (!cpu_isset(cpu, newdev->cpumask))
- goto out;
+ goto out_bc;

td = &per_cpu(tick_cpu_device, cpu);
curdev = td->evtdev;
@@ -265,7 +265,7 @@ out_bc:
*/
if (tick_check_broadcast_device(newdev))
ret = NOTIFY_STOP;
-out:
+
spin_unlock_irqrestore(&tick_device_lock, flags);

return ret;
Index: linux-2.6.22-rc5/kernel/time/tick-broadcast.c
===================================================================
--- linux-2.6.22-rc5.orig/kernel/time/tick-broadcast.c 2007-06-17 08:52:07.000000000 +0200
+++ linux-2.6.22-rc5/kernel/time/tick-broadcast.c 2007-06-17 08:52:10.000000000 +0200
@@ -64,8 +64,9 @@ static void tick_broadcast_start_periodi
*/
int tick_check_broadcast_device(struct clock_event_device *dev)
{
- if (tick_broadcast_device.evtdev ||
- (dev->features & CLOCK_EVT_FEAT_C3STOP))
+ if ((tick_broadcast_device.evtdev &&
+ tick_broadcast_device.evtdev->rating >= dev->rating) ||
+ (dev->features & CLOCK_EVT_FEAT_C3STOP))
return 0;

clockevents_exchange_device(NULL, dev);
@@ -519,11 +520,9 @@ static void tick_broadcast_clear_oneshot
*/
void tick_broadcast_setup_oneshot(struct clock_event_device *bc)
{
- if (bc->mode != CLOCK_EVT_MODE_ONESHOT) {
- bc->event_handler = tick_handle_oneshot_broadcast;
- clockevents_set_mode(bc, CLOCK_EVT_MODE_ONESHOT);
- bc->next_event.tv64 = KTIME_MAX;
- }
+ bc->event_handler = tick_handle_oneshot_broadcast;
+ clockevents_set_mode(bc, CLOCK_EVT_MODE_ONESHOT);
+ bc->next_event.tv64 = KTIME_MAX;
}

/*
-
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