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From: Daniel Phillips <phillips@bonn-fries.net>
To: J Sloan <jjs@pobox.com>,
        Dieter =?iso-8859-15?q?N=FCtzel?= <Dieter.Nuetzel@hamburg.de>
Subject: Re: [2.4.17/18pre] VM and swap - it's really unusable
Date: Mon, 14 Jan 2002 10:08:51 +0100
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        Linux Kernel List <linux-kernel@vger.kernel.org>
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On January 14, 2002 12:33 am, J Sloan wrote:
> Dieter N?tzel wrote:
> >You told me that TUX show some problems with preempt before. What
> >problems? Are they TUX specific?
>
> On a kernel with both tux and preempt, upon
> access to the tux webserver the kernel oopses
> and tux dies...

Ah yes, I suppose this is because TUX uses per-cpu data as a replacement 
for spinlocks.  Patches that use per-cpu shared data have to be 
preempt-aware.  Ingo didn't know this when he wrote TUX since preempt didn't 
exist at that time and didn't even appear to be on the horizon.  He's 
certainly aware of it now.

> OTOH the low latency patch plays quite well
> with tux. As said, I have no anti-preempt agenda,
> I just need for whatever solution I use to work,
> and not crash programs and services we use.

Right, and of course that requires testing - sometimes a lot of it.  This one 
is a 'duh' that escaped notice. temporarily.  It probably would have been 
caught sooner if we'd started serious testing/discussion sooner.

--
Daniel
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