Messages in this thread | | | Date | Fri, 11 May 2007 22:34:13 -0700 | From | "H. Peter Anvin" <> | Subject | Re: [PATCH] "volatile considered harmful", take 3 |
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Satyam Sharma wrote: > >> + - Pointers to data structures in coherent memory which might be >> modified >> + by I/O devices can, sometimes, legitimately be volatile. A ring >> buffer >> + used by a network adapter, where that adapter changes pointers to >> + indicate which descriptors have been processed, is an example of >> this >> + type of situation. > > is a legitimate use case for volatile is still not clear to me (I > agree with Alan's > comment in a previous thread that this seems to be a case where a memory > barrier would be applicable^Wbetter, actually). I could be wrong here, so > would be nice if Peter explains why volatile is legitimate here. > > Otherwise, it's fine with me. >
I don't see why Alan's way is necessarily better; it should work but is more heavy-handed as it's disabling *all* optimization such as loop invariants across the barrier.
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