Messages in this thread | ![/](/images/icornerl.gif) | | From | David Howells <> | Subject | Re: [PATCH] WorkStruct: Implement generic UP cmpxchg() where an arch doesn't support it | Date | Fri, 08 Dec 2006 16:56:57 +0000 |
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Christoph Lameter <clameter@sgi.com> wrote:
> cmpxchg is the simplest solution to realize many other atomic operations and > its widely available on a wide variety of platforms.
But by no means all. Where it doesn't exist it can only be properly emulated by something such as LL/SC if they are there. If not, then you can't do a safe cmpxchg on SMP.
> It is the most universal atomic instruction that I know of.
I think TAS-type things and XCHG-type things are more common.
In fact I think more things have LL/SC than have CMPXCHG.
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