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To: Ingo Oeser <ingo.oeser@informatik.tu-chemnitz.de>
Cc: Linus Torvalds <torvalds@transmeta.com>,
        Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: light weight user level semaphores
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Reply-To: drepper@cygnus.com (Ulrich Drepper)
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From: Ulrich Drepper <drepper@redhat.com>
Date: 19 Apr 2001 13:40:19 -0700
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Ingo Oeser <ingo.oeser@informatik.tu-chemnitz.de> writes:

> Are you sure, you can implement SMP-safe, atomic operations (which you need
> for all up()/down() in user space) WITHOUT using privileged
> instructions on ALL archs Linux supports?

Which processors have no such instructions but are SMP-capable?

> How do we do this on nccNUMA machines later? How on clusters[1]?

Clusters are not my problem.  They require additional software.  And
NUMA machines maybe be requiring a certain sequence in which the
operations must be performed and the hardware should take care of the
rest.


I don't really care what the final implementation will be like.  For
UP and SMP machines I definitely want to have as much as possible at
user-level.  If you need a special libpthread for NUMA machines, so be
it.

-- 
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Ulrich Drepper  \    ,-------------------'   \  Sunnyvale, CA 94089 USA
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