Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 0b046b21 authored by John Stultz's avatar John Stultz Committed by Ingo Molnar
Browse files

clocksource: Improve clocksource watchdog reporting 



The clocksource watchdog reporting has been less helpful
then desired, as it just printed the delta between
the two clocksources. This prevents any useful analysis
of why the skew occurred.

Thus this patch tries to improve the output when we
mark a clocksource as unstable, printing out the cycle
last and now values for both the current clocksource
and the watchdog clocksource. This will allow us to see
if the result was due to a false positive caused by
a problematic watchdog.

Signed-off-by: default avatarJohn Stultz <john.stultz@linaro.org>
Cc: Dave Jones <davej@codemonkey.org.uk>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Stephen Boyd <sboyd@codeaurora.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1426133800-29329-9-git-send-email-john.stultz@linaro.org


[ Minor cleanups of kernel messages. ]
Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent 4ca22c26

kernel/time/clocksource.c

+9 −9
Original line number Original line Diff line number Diff line
@@ -142,13 +142,6 @@ static void __clocksource_unstable(struct clocksource *cs) 
		schedule_work(&watchdog_work);

		schedule_work(&watchdog_work);

}

}





static void clocksource_unstable(struct clocksource *cs, int64_t delta)

{

	printk(KERN_WARNING "Clocksource %s unstable (delta = %Ld ns)\n",

	       cs->name, delta);

	__clocksource_unstable(cs);

}



/**

/**

 * clocksource_mark_unstable - mark clocksource unstable via watchdog

 * clocksource_mark_unstable - mark clocksource unstable via watchdog

 * @cs:		clocksource to be marked unstable

 * @cs:		clocksource to be marked unstable
@@ -174,7 +167,7 @@ void clocksource_mark_unstable(struct clocksource *cs) 
static void clocksource_watchdog(unsigned long data)

static void clocksource_watchdog(unsigned long data)

{

{

	struct clocksource *cs;

	struct clocksource *cs;

	cycle_t csnow, wdnow, delta;

	cycle_t csnow, wdnow, cslast, wdlast, delta;

	int64_t wd_nsec, cs_nsec;

	int64_t wd_nsec, cs_nsec;

	int next_cpu, reset_pending;

	int next_cpu, reset_pending;
@@ -213,6 +206,8 @@ static void clocksource_watchdog(unsigned long data) 




		delta = clocksource_delta(csnow, cs->cs_last, cs->mask);

		delta = clocksource_delta(csnow, cs->cs_last, cs->mask);

		cs_nsec = clocksource_cyc2ns(delta, cs->mult, cs->shift);

		cs_nsec = clocksource_cyc2ns(delta, cs->mult, cs->shift);

		wdlast = cs->wd_last; /* save these in case we print them */

		cslast = cs->cs_last;

		cs->cs_last = csnow;

		cs->cs_last = csnow;

		cs->wd_last = wdnow;

		cs->wd_last = wdnow;
@@ -221,7 +216,12 @@ static void clocksource_watchdog(unsigned long data) 




		/* Check the deviation from the watchdog clocksource. */

		/* Check the deviation from the watchdog clocksource. */

		if ((abs(cs_nsec - wd_nsec) > WATCHDOG_THRESHOLD)) {

		if ((abs(cs_nsec - wd_nsec) > WATCHDOG_THRESHOLD)) {

			clocksource_unstable(cs, cs_nsec - wd_nsec);

			pr_warn("timekeeping watchdog: Marking clocksource '%s' as unstable, because the skew is too large:\n", cs->name);

			pr_warn("	'%s' wd_now: %llx wd_last: %llx mask: %llx\n",

				watchdog->name, wdnow, wdlast, watchdog->mask);

			pr_warn("	'%s' cs_now: %llx cs_last: %llx mask: %llx\n",

				cs->name, csnow, cslast, cs->mask);

			__clocksource_unstable(cs);

			continue;

			continue;

		}

		}