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clocksource: make clocksource watchdog cycle through online CPUs

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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));
}
}
}