Subject: Re: [PATCH] fix __mod_timer vs __run_timers deadlock.
From: Lee Revell <rlrevell@joe-job.com>
To: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Juergen Kreileder <jk@blackdown.de>, Andrew Morton <akpm@osdl.org>,
       Oleg Nesterov <oleg@tv-sign.ru>, linux-kernel@vger.kernel.org,
       maneesh@in.ibm.com
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	 <20050501023149.6908c573.akpm@osdl.org>  <87vf61kztb.fsf@blackdown.de>
	 <1115079230.6155.35.camel@gaston>
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Date: Mon, 02 May 2005 21:24:13 -0400
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On Tue, 2005-05-03 at 10:13 +1000, Benjamin Herrenschmidt wrote:
> Well, there may be other issues brought by this new timer code though.
> I'm running G5s regulary without a lockup or anything for weeks, so it
> would be interesting if you could try to find out what's involved in
> that other lockup you had.

It seems like it would not be to hard to create a timer test suite that
just hammers the timer subsystem, creating and deleting and modifying
zillions of timers, changing the system time, etc.  Combined with
running with HZ=10000 or something it seems like you could shake out
bugs a lot faster than just running & waiting for a race to show up.

I've seen timer related issues (the set_rtc_mmss issue that George
Anzinger fixed) while testing the RT patchset that I could only ever
reproduce once.

Lee


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