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    SubjectRe: spin_unlock optimization(i386)
    On 30 Nov 1999, Stefan Monnier wrote:

    >>>>>> "Andrea" == Andrea Arcangeli <andrea@suse.de> writes:
    >> Because the write buffer as documented is not allowed to show changes to
    >> the other cpus not in processor order. It can only delay the writes
    >> undefinitely but that make no difference at all for SMP.
    >
    >Of course it makes a difference:
    >
    > A = 1 B = 0
    > read B read A

    For the above it make no difference if there's a write buffer or not.

    Just replace the A = 1 and B = 0 with a `make A visible to other CPUs' and
    `make B visible to other CPUs' and move the two writes some hour before.

    Speculation is a completly different issue.

    Feel free to ask further if I am not been clear enough.

    Andrea


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