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clockevents: Make minimum delay adjustments configurable

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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>
This commit is contained in:
Martin Schwidefsky
2011-08-23 15:29:42 +02:00
committed by Thomas Gleixner
parent 29c158e81c
commit d1748302f7
8 changed files with 123 additions and 94 deletions
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kernel/time/tick-common.c
+2 -2
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@@ -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);
}