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    SubjectRe: [PATCH] make atomic_t volatile on all architectures
    On Thu, Aug 09, 2007 at 03:47:57AM -0400, Chris Snook wrote:
    >
    > If they're not doing anything, sure. Plenty of loops actually do some sort
    > of real work while waiting for their halt condition, possibly even work
    > which is necessary for their halt condition to occur, and you definitely
    > don't want to be doing cpu_relax() in this case. On register-rich
    > architectures you can do quite a lot of work without needing to reuse the
    > register containing the result of the atomic_read(). Those are precisely
    > the architectures where barrier() hurts the most.

    I have a problem with this argument. The same loop could be
    using a non-atomic as long as the updaters are serialised. Would
    you suggest that we turn such non-atomics into volatiles too?

    Any loop that's waiting for an external halt condition either
    has to schedule away (which is a barrier) or you'd be busy
    waiting in which case you should use cpu_relax.

    Do you have an example where this isn't the case?

    Cheers,
    --
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