From: Andreas Dilger <adilger@clusterfs.com>
To: "Richard B. Johnson" <root@chaos.analogic.com>
Cc: Peter Surda <shurdeek@panorama.sth.ac.at>, linux-kernel@vger.kernel.org
Subject: Re: Uptime timer-wrap
Date: Thu, 5 Sep 2002 15:25:16 -0600 [thread overview]
Message-ID: <20020905212516.GN7887@clusterfs.com> (raw)
In-Reply-To: <Pine.LNX.3.95.1020905160808.141A-100000@chaos.analogic.com>
On Sep 05, 2002 16:16 -0400, Richard B. Johnson wrote:
> I tried to simulate your observation by making a driver that
> set the 'jiffies' count upon an 'open'. The idea was to get
> the jiffies count to something close to wrap so I didn't have to
> wait a long time.
>
> Anyway, I found that setting the jiffies count to more than a
> few hundred counts into the future, causes the machine to halt
> with no interrupts (no Capslock, no NumLock, no network ping, etc).
>
> The machine just stops and I don't understand why.
>
>
> spin_lock_irqsave(&xlock, flags);
> jiffies += 0x1000;
> spin_lock_irqrestore(&xlock, flags);
>
> ... works just fine, but, changing 0x1000 to 0x7fffffff causes
> the machine to stop as reported.
>
> Does anybody have a clue?
Yes, because now some kernel code is going to wait 147 days - 1s
or something like that to finish.
See Tim Schmielau <tim@physik3.uni-rostock.de> patch for testing jiffies
wrap. It _initializes_ jiffies to a high pre-wrap value, maybe 5
minutes before wrap, instead of playing around with the jiffies value
after the system is running.
Cheers, Andreas
--
Andreas Dilger
http://www-mddsp.enel.ucalgary.ca/People/adilger/
http://sourceforge.net/projects/ext2resize/
next prev parent reply other threads:[~2002-09-05 21:23 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2002-09-05 18:02 odd network freezing, reboot fixed Peter Surda
2002-09-05 20:16 ` Uptime timer-wrap Richard B. Johnson
2002-09-05 21:25 ` Andreas Dilger [this message]
2002-09-06 12:06 ` Richard B. Johnson
2002-09-06 12:53 ` Zwane Mwaikambo
2002-09-06 12:41 ` Richard B. Johnson
2002-09-05 21:44 ` Peter Surda
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