Messages in this thread | | | Date | Tue, 13 Dec 2005 11:13:00 +0100 | From | Ingo Molnar <> | Subject | Re: [PATCH 1/19] MUTEX: Introduce simple mutex implementation |
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* David Howells <dhowells@redhat.com> 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.
take a look at the PREEMPT_RT implementation of mutexes: it uses cmpxchg(), and thus both the down() and the up() fastpath is lockless! (And that is a mutex type that does alot more things, as it supports priority inheritance.)
architectures which dont have cmpxchg can use a spinlock just fine.
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