linux-kernel - Re: TSC not updating after resume: Bug or Feature?

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Date:	Mon, 22 Dec 2008 15:48:36 +0100 (CET)
From:	Thomas Gleixner <tglx@...utronix.de>
To:	Fabio Comolli <fabio.comolli@...il.com>
cc:	"Rafael J. Wysocki" <rjw@...k.pl>, Ingo Molnar <mingo@...e.hu>,
	Peter Zijlstra <peterz@...radead.org>,
	Steven Rostedt <srostedt@...hat.com>, dsaxena@...xity.net,
	linux-kernel@...r.kernel.org,
	Dave Kleikamp <shaggy@...ux.vnet.ibm.com>
Subject: Re: TSC not updating after resume: Bug or Feature?

Fabio,

On Sun, 21 Dec 2008, Fabio Comolli wrote:
> Well, I'm the submitter of bug 12155 and I never had hpet=force on my
> command line. I don't know where you found it.
> Actually my command line is:

My bad. I confused it with the HPET force enable. (Your BIOS does not
advertise HPET).
 
> By the way, I don't know if it matters but the problema happened with
> in-kernel hibernation and also in out-of-tree TuxOnIce hibernation.
> Maybe this can help debugging the issue, I don't know.

Hmm, does not ring a bell here. Can you please apply the patch below
to mainline and retest ?

Thanks,

	tglx
-----
diff --git a/kernel/sched_clock.c b/kernel/sched_clock.c
index e8ab096..c18a6dd 100644
--- a/kernel/sched_clock.c
+++ b/kernel/sched_clock.c
@@ -86,6 +86,14 @@ void sched_clock_init(void)
 	sched_clock_running = 1;
 }
 
+void sched_clock_debug(void)
+{
+	struct sched_clock_data *scd = this_scd();
+
+	printk(KERN_INFO "SCD raw %llu gtod %llu clock %llu now %llu\n",
+	       scd->tick_raw, scd->tick_gtod, scd->clock, sched_clock());
+}
+
 /*
  * min,max except they take wrapping into account
  */
@@ -118,13 +126,13 @@ static u64 __update_sched_clock(struct sched_clock_data *scd, u64 now)
 
 	/*
 	 * scd->clock = clamp(scd->tick_gtod + delta,
-	 * 		      max(scd->tick_gtod, scd->clock),
-	 * 		      scd->tick_gtod + TICK_NSEC);
+	 *		      max(scd->tick_gtod, scd->clock),
+	 *		      max(scd->clock, scd->tick_gtod + TICK_NSEC));
 	 */
 
 	clock = scd->tick_gtod + delta;
 	min_clock = wrap_max(scd->tick_gtod, scd->clock);
-	max_clock = scd->tick_gtod + TICK_NSEC;
+	max_clock = wrap_max(scd->clock, scd->tick_gtod + TICK_NSEC);
 
 	clock = wrap_max(clock, min_clock);
 	clock = wrap_min(clock, max_clock);
diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
index fa05e88..bafbd2d 100644
--- a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -304,6 +304,8 @@ static int timekeeping_suspended;
 /* time in seconds when suspend began */
 static unsigned long timekeeping_suspend_time;
 
+extern void sched_clock_debug(void);
+
 /**
  * timekeeping_resume - Resumes the generic timekeeping subsystem.
  * @dev:	unused
@@ -336,6 +338,8 @@ static int timekeeping_resume(struct sys_device *dev)
 	timekeeping_suspended = 0;
 	write_sequnlock_irqrestore(&xtime_lock, flags);
 
+	sched_clock_debug();
+
 	touch_softlockup_watchdog();
 
 	clockevents_notify(CLOCK_EVT_NOTIFY_RESUME, NULL);
@@ -357,6 +361,8 @@ static int timekeeping_suspend(struct sys_device *dev, pm_message_t state)
 	timekeeping_suspended = 1;
 	write_sequnlock_irqrestore(&xtime_lock, flags);
 
+	sched_clock_debug();
+
 	clockevents_notify(CLOCK_EVT_NOTIFY_SUSPEND, NULL);
 
 	return 0;

--
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