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Subject: Re: a number and two questions for bob

Author: Robert Hyatt

Date: 08:24:15 05/06/04

Go up one level in this thread


On May 06, 2004 at 05:39:54, martin fierz wrote:

>On May 05, 2004 at 18:24:11, Robert Hyatt wrote:
>
>[snip]
>
>>I see 16-cpu speedups vary from 6.0 to 15.3.  That is not "very small
>>variability" if we are talking about the same thing.
>
>we are not talking about the same thing because very clearly i was talking about
>the 4CPU test.

OK.  My misunderstanding...  I was talking about variability in general.

In CB the variability is lower, because when I choose to split, I can look at
the whole tree to see what is going on and choose to split wherever I want.  In
Crafty, I can split _here_ or wait until later, (here = current ply after at
least one move has been searched serially).


>
>> The numbers are all over
>>the chart, just like current parallel numbers are with Crafty...
>
>so be it - that's fine with me, because that will all become part of the
>standard deviation and the standard error....
>in the end, perhaps you get a number which says
>
>speedup(4) = 3.1 +- 0.4
>
>don't you realize that this is a much more valuable result than
>
>speedup(4) = 3.1 ??



Yes but I have never claimed speedup(4)=3.1

I have _always_ claimed that my speedup formula is a _rough approximation_ that
varies even on the same problem set, or on different problem sets...  IE it's a
linear fit to a non-linear function...



>
>whatever it is, just post those numbers you just posted for DTS for crafty (and
>vincent and GCP should post their numbers giving 2.8 and 3.0 too), then we can
>calculate the stats, and see whether this is just a random noise thing or rather
>a statistically significant effect.
>
>which would finally stop this fruitless discussion...

I ran tests on the quad opteron.  I believe I have logs for 1, 2, 3 and 4 cpus,
I'll grab those off of a offline disk today and post the times as you
requested...

But I don't believe it will "stop this fruitless discussion" as I have posted
the same kinds of numbers previously and it apparently didn't help at all.




>
>cheers
>  martin



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