Messages in this thread | | | Date | Tue, 30 Nov 1999 16:35:44 +0100 (CET) | From | Andrea Arcangeli <> | Subject | Re: spin_unlock optimization(i386) |
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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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