Messages in this thread Patch in this message | | | From | yanghui <> | Subject | [PATCH] Clocksource: Avoid misjudgment of clocksource | Date | Fri, 8 Oct 2021 16:03:05 +0800 |
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clocksource_watchdog is executed every WATCHDOG_INTERVAL(0.5s) by Timer. But sometimes system is very busy and the Timer cannot be executed in 0.5sec. For example,if clocksource_watchdog be executed after 10sec, the calculated value of abs(cs_nsec - wd_nsec) will be enlarged. Then the current clocksource will be misjudged as unstable. So we add conditions to prevent the clocksource from being misjudged.
Signed-off-by: yanghui <yanghui.def@bytedance.com> --- kernel/time/clocksource.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/kernel/time/clocksource.c b/kernel/time/clocksource.c index b8a14d2fb5ba..d535beadcbc8 100644 --- a/kernel/time/clocksource.c +++ b/kernel/time/clocksource.c @@ -136,8 +136,10 @@ static void __clocksource_change_rating(struct clocksource *cs, int rating); /* * Interval: 0.5sec. + * MaxInterval: 1s. */ #define WATCHDOG_INTERVAL (HZ >> 1) +#define WATCHDOG_MAX_INTERVAL_NS (NSEC_PER_SEC) static void clocksource_watchdog_work(struct work_struct *work) { @@ -404,7 +406,9 @@ static void clocksource_watchdog(struct timer_list *unused) /* Check the deviation from the watchdog clocksource. */ md = cs->uncertainty_margin + watchdog->uncertainty_margin; - if (abs(cs_nsec - wd_nsec) > md) { + if ((abs(cs_nsec - wd_nsec) > md) && + cs_nsec < WATCHDOG_MAX_INTERVAL_NS && + wd_nsec < WATCHDOG_MAX_INTERVAL_NS) { pr_warn("timekeeping watchdog on CPU%d: Marking clocksource '%s' as unstable because the skew is too large:\n", smp_processor_id(), cs->name); pr_warn(" '%s' wd_nsec: %lld wd_now: %llx wd_last: %llx mask: %llx\n", -- 2.20.1
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