Author: Robert Hyatt
Date: 08:39:28 01/15/04
Go up one level in this thread
On January 15, 2004 at 09:59:22, Gordon Rattray wrote: >On January 15, 2004 at 00:04:33, Robert Hyatt wrote: > >>On January 14, 2004 at 18:10:50, Jeroen van Dorp wrote: >> >>>>I'm not sure what you mean. I've _always_ maintained that the best long-game >>>>engine is not necessarily the best short-game engine. It is _possible_ that >>>>is true, but it is not guaranteed. So taking a long game and reducing it to >>>>milliseconds-per-move at the end can change the result and skew the overall >>>>outcome. Or just turn it into a coin-flip as to who makes the first mistake >>>>and actually suffers for it. >>> >>>The thought doesn't go that deep :) >>>It might be that you're just testing time management. It is true that an engine >>>can return nonsense in a millisecond if it has to. However I feel that the true >>>strenght of an engine is first of all the ability to find a correct solution, >>>secondly to find it in the shortest time span, and thirdly to find it in the >>>time alotted. I.e. there's a hierarchy in determining what makes an engine >>>"best". >>> >>>J. >> >>At ultra-fast time controls, serendipity wins more games than it should. >> >>That was why I suspected that increments are popular, nobody gets into a wild >>time-scramble. Or one program doesn't get into a lucky ponder-cycle and save >>enough time to put the opponent into a fast blitz mode at a fraction of a second >>per move. > > >Very interesting. > >So, supposing I have two PCs, with PC1 being faster than PC2 (both single CPU). >Assume everying else is the same between them (engine, book, etc.). What's the >best time control for PC1's faster hardware to show it's superiority? Superiority in what? Blitz games or long time controls? If you are interested in blitz, I'd play blitz. If you are interested in 40/2hr, I'd play 40 moves in 2 hours. > >I think that a faster time control is required, as this has the best chance of >PC1 gaining a deeper search depth than PC2. The fact that both are using the >same engine is crucial to my thinking here. I'm also using the belief that >deeper searches have diminishing returns, although I'm not sure of the latest >thoughts/data on this. Using the same program on both is one thing. I was discussing two different programs playing a match... > >But now let's complicate things a bit... > >Suppose PC1 is a dual CPU. PC2 is a single CPU. PC1 still generally faster >while using both CPUs, but slower than PC1 if only using one CPU - assume 2 in >use. Engine still the same, and SMP capable. > >Could this change matters? Could the fact that PC1 is running SMP - and hence >the search is undeterministic - mean that PC1's search is more "hit and miss" >and that luck starts to play more of a part? Or will the SMP search be lucky >and unlucky in such a manner that it balances itself out and doesn't matter >overall? Here is my answer. Run the program on machine 1 (single cpu machine) and look at the NPS. Run the program on machine 2 using 2 cpus, but here take the NPS and divide by 2 to convert to 1 cpu number, then multiply by 1.7 as that will be the rough approximation to the parallel speedup. Compare that number to the single-cpu machine's NPS. The faster NPS should win, the wider the margin in speed, the wider the margin in wins. > >As a side note, I've recently run through some of the Nolot test suite with a >SMP engine and the range of times (for the same test case) was greater than I >thought. > >Gordon You haven't been reading my posts here very long then. :) I have pointed this out hundreds of times and given amazing examples of how wildly SMP results can vary. Even though one or two claim a variance of < 1% for _their_ program... This makes testing and evaluation of changes _very_ complicated, as you can see.
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