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Subject[PATCH v2] Improve clocksource unstable warning
Date
When the system goes out to lunch for a long time, the clocksource
watchdog might get false positives. Clarify the warning so that
people stop blaming their system freezes on the timing code.

This change was Thomas Gleixner's suggestion.

Signed-off-by: Andy Lutomirski <luto@mit.edu>
---

This version compares directly (and tediously to avoid overflow) with
max_idle_ns.

kernel/time/clocksource.c | 6 ++++--
1 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/kernel/time/clocksource.c b/kernel/time/clocksource.c
index c18d7ef..f8cef8b 100644
--- a/kernel/time/clocksource.c
+++ b/kernel/time/clocksource.c
@@ -215,8 +215,10 @@ static void __clocksource_unstable(struct clocksource *cs)

static void clocksource_unstable(struct clocksource *cs, int64_t delta)
{
- printk(KERN_WARNING "Clocksource %s unstable (delta = %Ld ns)\n",
- cs->name, delta);
+ printk(KERN_WARNING "Clocksource %s unstable (delta = %Ld ns)%s\n",
+ cs->name, delta,
+ (delta < 0 && (u64)-delta > watchdog->max_idle_ns) ?
+ " or your system lagged for other reasons" : "");
__clocksource_unstable(cs);
}

--
1.7.3.2


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