Author: Vincent Diepeveen
Date: 08:05:25 05/03/04
Go up one level in this thread
On May 03, 2004 at 09:20:51, martin fierz wrote: >On May 03, 2004 at 02:14:53, Vincent Diepeveen wrote: > >>On May 02, 2004 at 18:49:38, Robert Hyatt wrote: >> >>>On May 02, 2004 at 18:23:44, Gian-Carlo Pascutto wrote: >>> >>>>On May 02, 2004 at 13:12:04, Robert Hyatt wrote: >>>> >>>>>He sent me an email trying to justify his poor performance. He first claimed >>>>>that it was an artifact of null-move. Testing disproved that. >>>> >>>>What testing? >>>> >>>>-- >>>>GCP >>> >>> >>>The testing you and I both did. It showed a minimal speedup difference if you >>>recall. 2.8 vs 3.1... not _that_ significant... >> >>2.8 for with nullmove >>3.0 for without nullmove >> >>A major difference. based upon 30+ positions. >> >>And both not *close* to speedup(n) = 1.0 + 0.7(n-1) > >i know nothing about this thread, i know nothing about multiprocessing, but i do >know that the above formula gives 3.1 for n=4. >i don't know about you, but i consider both 2.8 and 3.0 to be "close" to 3.1 - >as a physicist, i tend to think of numbers within 10% as equal ;-) For the default version it is 2.8 and that's far away from 3.1. 10% is not 'a little bit'. In computerchess people like Frans Morsch work an entire year for 0.5%. Further Hyatt has done a very clear claim in journal of ICGA that it is 0.7(n-1) + 1 for *any* number of processors. This where at n=4 it is already dead wrong. What about n = 64 ? So his entire article about crafty parallel scaling lineair with the number of cpu's getting 0.7 speedup out of any number of cpu's is just complete wrong again. Crafty at his own machine doesn't even get 3.1. Instead it gets 2.8. Of course not coincidental this happens when someone else than Hyatt himself is doing the test at his machine. In general Hyatt takes positions where the mainline is directly trivial to find so easy move ordering possible and where therefore splitting is never going to suffer any problems. Note he tried to 'disproof' the 2.8 at 30 positions by showing 3 positions he analyzed himself, both having the same 'boring mainline' conditions. The word objective testing and statistical analysis are not in his dictionary i guess. For the DTS article he has been proven frauding and he figured out a new formula to 'show' that his implementation lineairly scales (in speedup) at big machines. Note that just for 4 processors the difference averaged over a lot of positions from 2.8 versus 3.1 is a *big* difference. *all* tests done by others than hyatt show different numbers than what he writes up in journal of icga. then he complains that the machines tested are not good. then a test over 30 positions shows the point at his own quad and he still is disputing now because it falls 'within 10%' ? What a nonsense. >cheers > martin
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