On Fri, 24 Aug 2007, Denys Vlasenko wrote:
> On Thursday 16 August 2007 00:22, Paul Mackerras wrote:
> > Satyam Sharma writes:
> > In the kernel we use atomic variables in precisely those situations
> > where a variable is potentially accessed concurrently by multiple
> > CPUs, and where each CPU needs to see updates done by other CPUs in a
> > timely fashion. That is what they are for. Therefore the compiler
> > must not cache values of atomic variables in registers; each
> > atomic_read must result in a load and each atomic_set must result in a
> > store. Anything else will just lead to subtle bugs.
>
> Amen.
A "timely" fashion? One cannot rely on something like that when coding.
The visibility of updates is insured by barriers and not by some fuzzy
notion of "timeliness".
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