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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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