Author: Bob Durrett
Date: 09:07:16 02/18/04
Go up one level in this thread
On February 18, 2004 at 11:54:20, Keith Evans wrote: >On February 18, 2004 at 10:48:17, Bob Durrett wrote: > >>This is interesting. Some things that work well in software for the PC may work >>poorly in a given type of hardware and visa versa. I was intrigued by the >>possibility of making a hardware implementation of Crafty software, but perhaps >>much of the code in Crafty may have to be scrapped and replaced with other code >>more easy to convert to hardware. >> >>I can see also the possibility that there would be many design tradeoffs which >>would come out differently in a hardware implementation versus a software >>implementation [on a PC or other general-purpose computer]. >> >>Converting an existing software engine to a hardware engine would likely be >>sub-optimal for the above reasons. On the other hand, it might still be a >>worthwhile endeavor since the exercise would point to better ways to make the >>hardware chess engine in the future. >> >>When working with hardware, its always necessary to work within the existing >>state-of-the art and using existing hardware. This is a compromise which >>software people may not have to face other than having to use existing >>compilers. >> >>Just thinking out loud. : ) >> >>Bob D. > >This is why I joked that the Opteron is a hardware Crafty. I think that Bob has >really optimized Crafty to run on a 64-bit Von Neuman machine. I would not want >to try to accelerate it as-is with custom hardware. The best bet would be to >lobby AMD for some new instructions in a follow-on CPU ;-) > >You could make a custom 64-bit bitboard processor in an FPGA, but even if it >were more efficient in some operations it would be hard to compete with >something running at over 2 GHz. (It might be able to do things like manage >rotated bitboards much more efficiently.) Let's say that the FPGA ran at 200 >MHz. Unless the FPGA were 10X as efficient as the Opteron, it would not be >competitive. Then Bob trivially (since he's already done the SW work) moves to a >multi-Opteron system, and you need to figure out how to use your FPGAs in >parallel. > >In some ways the hardware versus software tradeoff can become a little >confusing. If Bob makes a custom Opteron board with 16 Opterons on that, and >then a custom backplane to hold 16 of those what do you call that? And if I >implement some custom processor in an FPGA and then write software for that >processor? Both involve a lot of custom design work. The cool thing about Bob's >approach is that you basically have a ton of people at Intel and AMD working on >the really tricky design and fabrication work. Even if Bob takes a vacation from >chess, the factories still work on these processors. And somebody else is >probably working on some custom backplane. > >From Hsu's thesis (discussing Deep Thought - please Vincent no Hsu bashing): > >"The philosophy behind the design of the Deep Thought evaluation function >hardware is a bit unusual. The overriding concerns are the circuit size and the >feasibility of future integration, possibly in a somewhat different form." >(Already thinking about Deep Blue.) "Sacrifices in the knowledge content of the >evaluation function were deemed justifiable if they simplified the circuit >design considerably." > >This applies to software-only programs too of course. Compare the speed of Diep >versus Crafty. Different design philosophy. > >You also might consider adding additional knowledge to custom hardware if it >fits, since it's likely that it can be done in parallel and not impact the speed >to the custom hardware. > >-K Good comments. I am reminded of the Fidelity Challenger discussed here recently. If the Fidelity guys had known then what is known today, their machine would have been much stronger. I suspect that we have not seen the last of dedicated chess-playing machines. You can do only so much on a general purpose sequential machine like a PC. Hydra is sort-of a half and half since it is hardware but, like a parasite, it still seems to need a PC [or equivalent] as a host. Bob D.
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