Messages in this thread | | | Subject | Re: [PATCH] Document Linux's memory barriers | From | Bryan O'Sullivan <> | Date | Tue, 07 Mar 2006 13:14:45 -0800 |
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On Tue, 2006-03-07 at 12:57 +0100, Andi Kleen wrote:
> > > True, I suppose. I should make it clear that these accessor functions imply > > > memory barriers, if indeed they do, > > > > They don't, but according to Documentation/DocBook/deviceiobook.tmpl > > they are performed by the compiler in the order specified. > > I don't think that's correct. Probably the documentation should > be fixed.
That's why I hedged my words with "according to ..." :-)
But on most arches those accesses do indeed seem to happen in-order. On i386 and x86_64, it's a natural consequence of program store ordering. On at least some other arches, there are explicit memory barriers in the implementation of the access macros to force this ordering to occur.
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