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Subject: Re: is the

Author: Ernst A. Heinz

Date: 00:55:31 07/21/98

Go up one level in this thread

On July 20, 1998 at 19:21:27, Dan Newman wrote:

>On July 20, 1998 at 17:02:51, Roberto Waldteufel wrote:
>>On July 20, 1998 at 15:20:24, Dan Newman wrote:
>>>On July 20, 1998 at 14:36:12, Bruce Moreland wrote:
>>>>On July 20, 1998 at 14:30:47, Dan Newman wrote:
>>>>>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.
>>>I bet that's it or at least a lot of it.  The major difference is that
>>>the deeper plies will have fewer pieces on average.  So move generation
>>>will be a little cheaper, a smaller portion of the moves generated
>>>will be wasted, and so forth.
>>Have you considered that the deeper iterations contain the most transpositions,
>>so you will process more nodes quickly by hash table look-up? I think this must
>>surely account for at least some of the difference.
>>Best wishes,
>I hadn't thought about that either--but I've seen the effect even
>without a transposition table.
>Actually, I'm beginning to return to my original guess--I've noticed
>this effect when benchmarking the move generator in isolation too, just
>generating the same set of moves over and over.  The longer the run,
>the more move generations per second.  I imagine this could be due to
>the branch prediction hardware settling into an improved (but probably
>not optimal) pattern.  Or, it could be the OS doing a lot of stuff
>immediately after loading the program in--disk accesses or whatever.
>Just one more in a series of quirky, unfathomable computer behaviors.

Or it could be a bug in your calculation procedure which amasses small
errors to larger ones over time ...


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