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Subject: Re: is the

Author: Bruce Moreland

Date: 11:36:12 07/20/98

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On July 20, 1998 at 14:30:47, Dan Newman wrote:

>I think I've seen this priming-the-pump effect--though perhaps not as
>pronounced as a 4% change in node rate.  Is it due to branch prediction
>being pre-set by the first run or some sort of alignment variation?

I don't know.  4% seems like a lot, but I've seen several percent at least,
discounting any disk I/O which would be cached on later runs, and could of
course result in even more difference.

I'm not a hardware guy.

>One of the biggest effects I see is that I get a much larger node rate
>the longer I run.  If I run a test for 10 s I might get 170 knps.  If
>I run for 40 s 200 knps.  It does level off of course.  I'm using a
>P6/200, so I've attributed this effect to improving branch prediction
>as the code runs.  Any ideas?

Maybe it has something to do with the deeper search having characterstics that
differ from the shallower search.


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