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clocksource: make clocksource watchdog cycle through online CPUs 

This way it checks if the clocks are synchronized between CPUs too.
This might be able to detect slowly drifting TSCs which only
go wrong over longer time.

Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
This commit is contained in:
Andi Kleen 2008-01-30 13:30:02 +01:00 committed by Thomas Gleixner
parent 3833eecc18
commit 6993fc5bbc
1 changed files with 14 additions and 4 deletions
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18
kernel/time/clocksource.c
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@ -141,8 +141,16 @@ static void clocksource_watchdog(unsigned long data)
}
if (!list_empty(&watchdog_list)) {
__mod_timer(&watchdog_timer,
watchdog_timer.expires + WATCHDOG_INTERVAL);
/*
* Cycle through CPUs to check if the CPUs stay
* synchronized to each other.
*/
int next_cpu = next_cpu(raw_smp_processor_id(), cpu_online_map);
if (next_cpu >= NR_CPUS)
next_cpu = first_cpu(cpu_online_map);
watchdog_timer.expires += WATCHDOG_INTERVAL;
add_timer_on(&watchdog_timer, next_cpu);
}
spin_unlock(&watchdog_lock);
}
@ -164,7 +172,8 @@ static void clocksource_check_watchdog(struct clocksource *cs)
if (!started && watchdog) {
watchdog_last = watchdog->read();
watchdog_timer.expires = jiffies + WATCHDOG_INTERVAL;
add_timer(&watchdog_timer);
add_timer_on(&watchdog_timer,
first_cpu(cpu_online_map));
}
} else {
if (cs->flags & CLOCK_SOURCE_IS_CONTINUOUS)
@ -185,7 +194,8 @@ static void clocksource_check_watchdog(struct clocksource *cs)
watchdog_last = watchdog->read();
watchdog_timer.expires =
jiffies + WATCHDOG_INTERVAL;
add_timer(&watchdog_timer);
add_timer_on(&watchdog_timer,
first_cpu(cpu_online_map));
}
}
}