Messages in this thread |  | | | Date | Wed, 14 Dec 2005 12:00:27 +1100 | | From | Nick Piggin <> | | Subject | Re: [PATCH 1/19] MUTEX: Introduce simple mutex implementation |
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David Howells wrote: > Nick Piggin <nickpiggin@yahoo.com.au> wrote: > > >>We have atomic_cmpxchg. Can you use that for a sufficient generic >>implementation? > > > No. CMPXCHG/CAS is not as available as XCHG, and it's also unnecessary. >
atomic_cmpxchg should be available on all platforms.
While it may be strictly unnecessary, if it can be used to avoid having a crappy default implementation that requires it to be reimplemented in all architectures then that would be a good thing.
Any arguments about bad scalability or RT behaviour of the hashed spinlock emulation atomic_t implementations are silly because they are used by all atomic_ operations. It is an arch implementation detail that generic code should not have to worry about.
-- SUSE Labs, Novell Inc.
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