From: Pavel Machek <pavel@ucw.cz>
To: "Joel K. Greene" <joel.greene@catapult.com>
Cc: linux-kernel@vger.kernel.org
Subject: Re: Timer interrupt stops, causes soft lockup
Date: Mon, 17 Mar 2008 16:46:39 +0100 [thread overview]
Message-ID: <20080317154639.GA4102@ucw.cz> (raw)
In-Reply-To: <1205510009.29658.83.camel@linuxdt036.nc.catapult.com>
Hi!
> Of course when time stops progessing forward at a steady pace all
> sorts of Bad Things happen.
>
> The clock loop is caused by jiffies not incrementing. It seems that wall
> time updates itself and then resync's with jiffies every ~4s.
>
> We verified that all spinlocks ( xtime_lock in particular ) were not
> being held, and that the kernel had no reason not to update jiffies.
> Other interrupts continue to fire, so we're not stuck in the timer
> handler.
>
> So, we went on to look at the PIC. We threw together a little kernel
> module to get some debug info.
Nice debugging.
> We have over 10 systems demonstrating the problem, many in customer
> sites.
Does nosmp help?
Does noapic/nolapic help?
You may want to try testing with HZ=4000... to show the problem
faster.
Pavel
--
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
next prev parent reply other threads:[~2008-03-17 15:46 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <1204653133.718.14.camel@linuxdt036.nc.catapult.com>
[not found] ` <47CD634E.2828.00B3.0@novell.com>
[not found] ` <1204722318.6578.12.camel@linuxdt036.nc.catapult.com>
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[not found] ` <47D6423D.1E6F.00AA.0@novell.com>
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[not found] ` <1205260328.18463.67.camel@linuxdt036.nc.catapult.com>
[not found] ` <47D68B9D.1E6F.00AA.0@novell.com>
[not found] ` <1205265642.18463.82.camel@linuxdt036.nc.catapult.com>
[not found] ` <1205322793.20205.9.camel@linuxdt036.nc.catapult.com>
[not found] ` <1205326713.20205.27.camel@linuxdt036.nc.catapult.com>
[not found] ` <1205332212.20205.33.camel@linuxdt036.nc.catapult.com>
2008-03-14 15:53 ` Joel K. Greene
2008-03-14 16:38 ` Arjan van de Ven
2008-03-14 17:21 ` Joel K. Greene
2008-03-15 5:30 ` Arjan van de Ven
2008-03-17 15:46 ` Pavel Machek [this message]
2008-03-18 14:40 ` Joel K. Greene
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