Re: light weight user level semaphores

Ulrich Drepper
2001-04-19T20:41:49Z

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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