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authorAndi Kleen <ak@suse.de>2008-01-30 13:30:02 +0100
committerThomas Gleixner <tglx@linutronix.de>2008-04-17 12:22:31 +0200
commit6993fc5bbc5d63ccd55985b39c34417e430e75e9 (patch)
tree6a1ea13d3f27a8063a9375689b729479c4e63e22
parent3833eecc183ce052e9ac96b39b45121a2d11ac16 (diff)
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>
-rw-r--r--kernel/time/clocksource.c18
1 files changed, 14 insertions, 4 deletions
diff --git a/kernel/time/clocksource.c b/kernel/time/clocksource.c
index 7f60097d443..912156dd600 100644
--- a/kernel/time/clocksource.c
+++ b/kernel/time/clocksource.c
@@ -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));
}
}
}