Author: enrico carrisco
Date: 01:46:33 03/18/03
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On March 18, 2003 at 00:01:44, Robert Hyatt wrote: >On March 17, 2003 at 22:59:30, Aaron Gordon wrote: > >>On March 17, 2003 at 18:47:27, Eugene Nalimov wrote: >> >>>I just run the experiment. I used 2 otherwise identical 64-bit systems, one with >>>3Mb of L3 cache, other with 1.5Mb. Machine with bigger cache run Crafty's >>>"bench" comman 12% faster (1 CPU). >>> >>>That means that >>>(1) Crafty's working set don't fit into 1.5Mb, >>>(2) For systems with cache 1.5Mb or less (i.e. for almost all x86 systems) for >>>Crafty memory speed matter. >>> >>>Thanks, >>>Eugene >> >>Those types of systems aren't what people normally use. Most people here have a >>Pentium 3, Athlon, Pentium 4, etc. Here is something I found with Crafty. >> >>Using the Nforce2 chipset I'm able to run the ram at speeds from 50% up to 200% >>(100% being synchronous) of the fsb speed. I tested 200MHz FSB (400DDR) with >>200MHz memory (400DDR) and 200fsb with 100MHz memory (200DDR). >>The difference between ~1.6gb/s memory and ~3.2gb/s memory with craftys 'bench' >>command was 0.14%. Yes, about one seventh of one percent. > >That might well suggest _another_ bottleneck in that particular machine.... What he didn't mention is that this _supposed_ bottlenecked machine is running crafty faster than any single P4/XEON available, both at 1.6gb/s and 3.2gb/s memory bandwidth. (Well, I guess there is that guy with the freon cooled P4 at 4GHz that is a hair faster...) Point being, there is no bottleneck here. Memory speeds have a fairly inelastic effect on overall chess engine performance (with regards to the abovementioned platorms.) -elc.
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