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SubjectRe: Uses for memory barriers
On Fri, 8 Sep 2006, Oliver Neukum wrote:

> It seems you are correct.
> Therefore the correct code on CPU 1 would be:
>
> y = -1;
> b = 1;
> //mb();
> //x = a;
> while (y < 0) relax();
>
> mb();
> x = a;
>
> assert(x==1 || y==1); //???
>
> And yes, it is confusing. I've been forced to change my mind twice.

Again you have misunderstood. The original code was _not_ incorrect. I
was asking: Given the code as stated, would the assertion ever fail?

The code _was_ correct for my purposes, namely, to illustrate a technical
point about the behavior of memory barriers.

Alan

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