Author: Robert Hyatt
Date: 07:05:58 09/22/01
Go up one level in this thread
On September 22, 2001 at 00:48:21, Uri Blass wrote: > >I do not express an opinion about the possible speed improvement that you can >get from parallel search today but >I do not see that the rest is already there. > >1)The fact that you need 2 minutes to implement R=3 in Cray blitz means nothing >if you did not test R=3 when you tested the speed improvement from parallel >search. I don't know what you mean here. In the Cray Blitz papers, I used R=1. That was what I used in the normal program. I have also reported here (many times) on the speedup for Crafty. Which is right in line with Cray Blitz. Null move has _nothing_ to do with parallel search efficiency. I have data from Cray Blitz with _no_ null-move. With R=1. And with Crafty with R=2 and R=2~3. There is no difference in the performance that I can find. So this entire discussion leaves me wondering just exactly what he is talking about. > >2)Vincent is right that the machine is hell slower than nowadays single cpus >because he talks about Cray blitz from 15 years ago and not about the latest >cray blitz that can search 7M nodes per second. 15 years ago would be the YMP. That is not "hell slow". The machine had 8 cpus at roughly 200mhz although that is not the way to measure the speed of a machine that can produce multiple arithmetic results in one clock cycle. I'd take that old YMP, circa 1986, over _any_ PC today for pure number-crunching. > >I understand that his claim is about long time control and the only way to test >if he is right is to take a lot of positions from games when the machine changes >it's mind after a long search and to compare the time that it needs >to do it without parallel search and the time that it needs to do it with >parallel search when the hash tables are the same. His claim is simply nonsense. I have explained why already. If he can produce a speedup of > 2 with 2 processors, then using two processes on a single-cpu machine will produce a speedup > 1. The proof is trivial. And the concept is ridiculous. > >I have positions when Deep Fritz changed it's mind after a long search from my >correspondence games but I have not multi processor. >If people are interested in testing it I may send them my positions >and they may use them in order to test the speed improvement of Deep Fritz from >parallel search. > >I agree that speed improvement of more than being 2 times faster from 2 >processors means that it is possible to improve the program when it is using 1 >proccesor. > >Uri Which means the test is simply invalid. The sequential search has to be fixed first.
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