[PATCH for 2.6.19] Fix xtime losing ticks

From: Jiri Bohac
Date: Thu Nov 16 2006 - 11:52:09 EST


xtime is not properly incremented when main timer ticks are lost.
Whatever the number of ticks elapsed is, only one tick worth of time
is added to xtime. This patch fixes that.

Signed-off-by: Jiri Bohac <jbohac@xxxxxxx>

Index: linux-2.6.19-rc5/kernel/timer.c
===================================================================
--- linux-2.6.19-rc5.orig/kernel/timer.c
+++ linux-2.6.19-rc5/kernel/timer.c
@@ -904,7 +904,7 @@ static void clocksource_adjust(struct cl
*
* Called from the timer interrupt, must hold a write on xtime_lock.
*/
-static void update_wall_time(void)
+static void update_wall_time(unsigned long ticks)
{
cycle_t offset;

@@ -915,7 +915,7 @@ static void update_wall_time(void)
#ifdef CONFIG_GENERIC_TIME
offset = (clocksource_read(clock) - clock->cycle_last) & clock->mask;
#else
- offset = clock->cycle_interval;
+ offset = ticks * clock->cycle_interval;
#endif
clock->xtime_nsec += (s64)xtime.tv_nsec << clock->shift;

@@ -1053,7 +1053,7 @@ void run_local_timers(void)
*/
static inline void update_times(unsigned long ticks)
{
- update_wall_time();
+ update_wall_time(ticks);
calc_load(ticks);
}

--
Jiri Bohac <jbohac@xxxxxxx>
SUSE Labs, SUSE CR

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