Re: spin_unlock optimization(i386)

Ingo Molnar (mingo@chiara.csoma.elte.hu)
Fri, 26 Nov 1999 17:33:55 +0100 (CET)


On Fri, 26 Nov 1999, Erich Boleyn wrote:

> > * you (speculatively) execute read instructions ahead of write
> > instructions.
> > * you do not send write instructions immediately out of the CPU core,
> > they sit in a write buffer.
>
> I'm starting to doubt myself a bit here (reads being hoisted above writes
> with respect to externally observed stores vs. conflicts with the list of
> uncommitted stores as being the trouble here), so I'm going to just check
> on this one with the folks who implemented it here...

my (fixed) test code doesnt show any causality violation. Manfred's code
is a complex simulation of one given Linux code sequence, Manfred are you
sure it's not buggy?

-- mingo

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