Author: Robert Hyatt
Date: 11:29:26 01/15/04
Go up one level in this thread
On January 15, 2004 at 12:44:08, Gordon Rattray wrote: >On January 15, 2004 at 11:39:28, Robert Hyatt wrote: > >[snip] > >>>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'm interested in PC1 winning as many games as possible over PC2. :-) I'm >thinking blitz is the answer (for my simplified conditions). > > >>> >>>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... > >Sure. I was highlighting this in order to compare with my main question... the >SMP case. I guessed it was easier to simplify the engine factor before varying >the hardware. > > >>> >>>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. > > >Ok. But if the two machines (same engine) play 10000 games at a "all in 1 >minute" control, and then another 10000 at "all in 10 min" control can we >expect the win ratio to be the same (allowing for statistical error margins)? > >As in the "two PCs, both single CPU" example, we'd expect a faster time control >to result in a bigger win ratio for the faster PC. But does the inclusion of a >SMP machine complicate this? Could an ultra-fast time control result in more >"unstable" searches and more "luck" being introduced? > > >>> >>>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. > > >Maybe I missed it. But it's more likely the figures just didn't hit home with >me till I seen it with my own eyes. :-) > >Gordon The search is exponential. The cpu difference is linear. Reducing the depth on both will favor the faster machine. IE I'd rather have a 4:3 ply advantage over my opponent than I would a 13:12 ply advantage.
This page took 0 seconds to execute
Last modified: Thu, 15 Apr 21 08:11:13 -0700
Current Computer Chess Club Forums at Talkchess. This site by Sean Mintz.