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Date: Thu, 16 Jan 2003 18:43:47 -0500 (EST)
From: Zwane Mwaikambo <zwane@holomorphy.com>
X-X-Sender: zwane@montezuma.mastecende.com
To: Joel Becker <Joel.Becker@oracle.com>
cc: lkml <linux-kernel@vger.kernel.org>, Alan Cox <alan@lxorguk.ukuu.org.uk>,
       Marcelo Tosatti <marcelo@conectiva.com.br>,
       Wim Coekaerts <Wim.Coekaerts@oracle.com>
Subject: Re: [PATCH] hangcheck-timer
In-Reply-To: <20030116231727.GV20972@ca-server1.us.oracle.com>
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On Thu, 16 Jan 2003, Joel Becker wrote:

> Folks,
> 	Attached is a patch adding hangcheck-timer.  It is used to detect
> when the system goes out to lunch for a period of time, and then
> returns.  This is interesting for debugging drivers as well as for
> clustering environments.
> 	The module sets a timer.  When the timer goes off, it then uses
> get_cycles() to determine how much real time has passed.
> 	On a normal system, the real elapsed time will be almost
> identical to the expected timer duration.  However, if a device decided
> to udelay for 60 seconds (or some other circumstance), the module takes
> notice.  If the margin of error passes a threshold, the driver prints a
> warning or the machine is rebooted.
> 	There are three parameters.

NMI watchdog? Doesn't look like this can catch cases where you have 
interrupts disabled and spinning on a lock, if you manage to run this code 
then the box isn't really locked up. In which case the software watchdog 
should be as good as this.

	Zwane
-- 
function.linuxpower.ca

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