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>
diff --git a/kernel/time/clocksource.c b/kernel/time/clocksource.c
index 7f60097..912156d 100644
--- a/kernel/time/clocksource.c
+++ b/kernel/time/clocksource.c
@@ -141,8 +141,16 @@
}
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 @@
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 @@
watchdog_last = watchdog->read();
watchdog_timer.expires =
jiffies + WATCHDOG_INTERVAL;
- add_timer(&watchdog_timer);
+ add_timer_on(&watchdog_timer,
+ first_cpu(cpu_online_map));
}
}
}