Subj : Re: What is the real costs of LOCK on x86 multiprocesor machine?
To   : comp.programming.threads
From : David Schwartz
Date : Fri Jul 29 2005 10:17 pm


"Mirek Fidler" <cxl@volny.cz> wrote in message 
news:3kuqnuF10818jU1@individual.net...
>I am unable to find anwswer to above question. Only tidbit of information 
>was that it is 100 cycles on P4, but perhaps that was just the worst case.
>
> Measuring the same on my uniprocesor AMD64 machine, LOCKed instructin seem 
> to be 3 times slower than regular one, but I guess that has only a little 
> relevance on real MP machine.

    On a p4, it's 100-200 clocks.

    DS

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