Author: Robert Hyatt
Date: 22:03:05 09/24/01
Go up one level in this thread
On September 24, 2001 at 22:37:37, Vincent Diepeveen wrote: >On September 24, 2001 at 09:19:57, Robert Hyatt wrote: > >>On September 23, 2001 at 18:32:50, Vincent Diepeveen wrote: >> >>> >>>The average test done here at CCC is 10 to 20 seconds a move. >>> >>>Even the new try to make a WACII the dudes test at most at 1 minute >>>a move. >>> >>>So you're kind of wrong here. >> >> >> >>You are mixing apples and oranges. The tests here have _nothing_ to do with >>trying to measure SMP efficiency. > >it has, at 1 minute a move my speedup is not even close to 2.0 > >it's more like 1.6 to 1.8 > >> >>> >>>Most tests in ICCA and advances in ICCA are based upon anything under or >>>equal to 8 ply. >> >>Again apples and oranges. _most_ ICCA and ACCX articles are pretty old when >>you look for ones dealing with parallel search. The older the article, the >>shallower the depth. If you find by DTS article you will not find _it_ >>based on shallow searches. In fact many of the single-cpu searches took >>_hours_ to run because the 16 cpu tests took minutes for each position. > >Yes and you claimed a 2.0 speedup at 2 processors. Pretty impressive >considering the time when you wrote the algorithm, and in assembly! what does the speedup have to do with the "time I wrote the algorithm?" Read my Ph.D. dissertation. good speedups are easy on worst-first move ordering searches. They are easy on best-first move ordering. They are not easy on normal chess-engine tree ordering... that is independent of time or anything. The old Cray's (C90 that I used in the JICCA paper for example) is as fast as anything today... > >> >> >>> >>>I can only remember a single article 'crafty goes deep' where some >>>deeper searches were done. >>> >> >> >> >>Find the DTS article. It had deep searches. >> >>And please don't start the "but Cray Blitz didn't use null-move R=3" > >You got 2.0, i get 2.0. > >Now you say i'm big shit somehow. > >Why? > >Note that the statement that i could do things on 1 processor quicker then >i can proof incorrect. If you can do the same thing which you do on 2 >processor but now on 1 processor, then that would implicitly mean that >2 processors are deterministic. Because behaviour at 1 processor is >deterministic for me. > >At 2 it is not. So i cannot do what i do on 2 processors in one process. > >How's that? > >>and such nonsense. I'll be happy to show you that the parallel speedup in >>Crafty is 100% independent of null-move usage. I can turn it off totally, > >Crafty is recursive Bob. You keep splitting at the wrong points too, >i have no idea what kind of difference that shows, more interesting is >if you can get cray blitz alive again and run it for my part at an old >cray but then with R=3 , no singular extensions and futility turned off. > >the interesting thing which you also didn't write down in your articles, >probably because of space is the speedup you get at the different depths. > >speedup at 8 ply, 9 ply, 10 ply, 11 ply , 12 ply etc. > >To see a graph of it. > >>use R=1 (or with a simple source change make it non-recursive R=1 just like >>CB) and produce some parallel speedup numbers. The speedup is independent of >>null-move although the overall search depth shrinks as expected. > >>Old SMP articles are not junk. If I were going to criticize _any_ SMP issues >>that have been reported, it would be anyone that claims that a speedup of > 2.0 >>is possible, while talking about how his move ordering is better than anybody >>else's. It simply isn't possible for _both_ of those conditions to be true. > >The difference is i never claimed it to be non improvable. You did a few years >ago though. You were not the only one saying it was hardly improvable. > >>One or the other, maybe. But a speedup > 2 means big problems in the non- >>parallel search. > > >> >> >>>> >>>>> Now, if that improvement isn't made, then you're testing a good >>>>>>parallel implementation against a poor sequential implementation, so your >>>>>>speedup value is meaningless. >>>>>> >>>>>>Dave >>>>> >>>>>The speedup value is not meaningless because it is possible that the cutomer >>>>>need to choose between poor sequential implementation and good parrallel >>>>>implentation so from the customer's point of view it may be important to know it >>>>>before deciding if to buy a machine with more processors. >>>> >>>>Parallel speedup is a scientific concept, used when reporting analyses of >>>>parallel search performance. What form of product is shipped to a chess >>>>software program customer is quite irrelevant. >>>> >>>>Dave
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