clockevents: Make minimum delay adjustments configurable

The automatic increase of the min_delta_ns of a clockevents device
should be done in the clockevents code as the minimum delay is an
attribute of the clockevents device.

In addition not all architectures want the automatic adjustment, on a
massively virtualized system it can happen that the programming of a
clock event fails several times in a row because the virtual cpu has
been rescheduled quickly enough. In that case the minimum delay will
erroneously be increased with no way back. The new config symbol
GENERIC_CLOCKEVENTS_MIN_ADJUST is used to enable the automatic
adjustment. The config option is selected only for x86.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: john stultz <johnstul@us.ibm.com>
Link: http://lkml.kernel.org/r/20110823133142.494157493@de.ibm.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

1 files changed, 2 insertions, 2 deletions

diff --git a/kernel/time/tick-common.c b/kernel/time/tick-common.c
index 119528de8235..da6c9ecad4e4 100644
--- a/kernel/time/tick-common.c
+++ b/kernel/time/tick-common.c
@@ -94,7 +94,7 @@ void tick_handle_periodic(struct clock_event_device *dev)
          */
         next = ktime_add(dev->next_event, tick_period);
         for (;;) {
-                if (!clockevents_program_event(dev, next, ktime_get()))
+                if (!clockevents_program_event(dev, next, false))
                         return;
                 /*
                  * Have to be careful here. If we're in oneshot mode,
@@ -137,7 +137,7 @@ void tick_setup_periodic(struct clock_event_device *dev, int broadcast)
                 clockevents_set_mode(dev, CLOCK_EVT_MODE_ONESHOT);
 
                 for (;;) {
-                        if (!clockevents_program_event(dev, next, ktime_get()))
+                        if (!clockevents_program_event(dev, next, false))
                                 return;
                         next = ktime_add(next, tick_period);
                 }