Re: AVL trees vs. Red-Black trees

Manfred (manfreds@colorfullife.com)
Tue, 7 Dec 1999 20:23:20 +0100

From: Ralf Baechle <ralf@uni-koblenz.de>
> They are, at least for everything that can (could ...) run Windows NT for
> which strong ordering is a requirement. This only covers ordering for
> cached memory accesses; ordering between cached and uncached accesses or
> uncached accesses is no generally strongly ordered and even for cached
> memory optionally more liberal ordering may be available as an option.

The PPC doesn't enforce strong ordering, and the PPC supported WinNT:
601:"loads and stores that miss the cache can be reordered as they arbitrate
for the system bus" (Chapter 4.10 from the PowerPC 601 RISC Microprocessor
User's Manual).
603: even speculative write operations that don't "alter the target
location" could occur.

I found no documentation about the Alpha, do you know if the full memory
barriers during spin_unlock() are required? The Alpha supported WinNT, and
_if_ the alpha enforces write ordering, then we could remove this memory
barrier/replace it with a weaker memory barrier.

Thanks,
Manfred

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