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Building A Homemade Chess Supercomputer
nado writes "There's a new article on Chessbase.com which has
GM John Nunn showing you his chess-orientated PC upgrade to a double Xeon system, with some Fritz benchmarks." Elsewhere in the article, John Nunn discusses the unique computer needs for chess computation: "One of the problems with currently available processors is that they are not particularly well suited to the integer calculations used for chess. A Pentium 4 will be slower at chess than a Pentium 3 of an equivalent clock speed."
IBM's Deep Blue used special purpose chips, so it shouldn't really come as too much of a surprise that general-purpose processors aren't the best for chess computers.
Yes, it is.
That's not insightful, that's dumb.
There is no great difference in performance between the AthlonXP and Pentium 4 lines. The small difference that exists is largely due to platform specific optimizations in the specific software benchmarked. That's relevant in the real world, sure, but it's not a measure of raw perfomance.
I don't think that it is in dispute that Intel went for low IPC/high clock at least partly because it was seen as good for PR -- with the MHz-race and MHz-myth and all.
It's with some humor we now see them back-peddle as they try to sell their high-performance low-energy processors which is clocked much lower than the P4s, but like the AthlonXP-line, have a higher IPC.
Belief is the currency of delusion.
First of all, the P4 is quite superior at doing tasks that are very mundane and repetitive. So simulators, counters, anything that performs the same operation on multiple data sets time and time again run very well on the P4.
Especially true with RDRAM, which has tremendous throughput but horrible latency.
The classic example of something the P4 is very good at: encoding frames of video into a compressed format such as MPEG-2. It's just cranking away through a big heap of data in a linear fashion.
Secondly, with branch prediction, the P4 out races competitors at some computer games,
Athlons do branch prediction, too. And they have a lower penalty for failure since their pipelines are shorter.
Branch prediction is very helpful also in the field of doing anything more than once because it knows what to expect next, and preps the processor for it.
What?!? Um, actually, branch prediction just keeps the chip's pipeline full. Branch prediction doesn't magically adapt the P4 to process data better, it simply allows the P4 to keep pipelineing instructions after a conditional branch. When a prediction is wrong, it must be backed out, which is expensive... but most of the time the prediction is good. (For example, a loop that does something 1000 times will have a conditional branch that will branch the same way 1000 times in a row, and then branch the other way the 1001th time. The prediction would be wrong that 1001th time, but would be correct for most of the other 1000.)
especially those that are optimised for P4 use.
It is hardly surprising that a P4 would do better than an Athlon at running P4-optimized code. However, this isn't a useless point, because Intel is the 800-pound gorilla and there are games optimized for the P4, and none for Athlons.
But AMD isn't about innovation, they are about making money plain and simple. Instead of making engines that try to predict the next move, they just built their processors with the very minimum everything, strapped on a few extra math units and away we go. This technique is very fast, but it's also expensive as most AMD users have learned, because all those extra adders do is add a LOT of ambient heat as the processor clocks up.
Actually, if you check the Thermal Design Power specs for equivalent-peforming AMD and Intel chips, the AMD chips run cooler.
So the P4 was for the mainstream user, to help spare some time from the physics boundry of the processor technology, and to improve on the things we do most on our computers today (music, videos, games).
Pure revisionist history. The P4 was designed for super high clock rates. They ripped too much stuff out of the design, so the P4 has some bad weaknesses it didn't need to have. That's why it's so critical to optimize code specifically for the P4 -- if you don't work around the flaws in the P4, it really hurts.
The Athlon, while it gets more work done per clock than the P4, isn't perfect. Its biggest problem is that it is physically very easy to destroy: you can fry it, or you can even crack its die trying to install a heat sink. The P4 with its heat spreader is much tougher, and with its built-in thermal throttling is more robust. AMD has learned its lesson, though, and the Opteron is robust.
Intel has aggressively marketed the P4 as The Multimedia Chip, but really an Athlon or a P4 will do well for multimedia stuff. The Opteron, for some specific kinds of tasks, will crush either one, and for other kinds of tasks will be slightly faster. I'm just guessing -- I haven't run benchmarks -- but I suspect that the Opteron will do very well on chess.
steveha
lf(1): it's like ls(1) but sorts filenames by extension, tersely