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Up Topic The Rybka Lounge / Computer Chess / What is the time equivalence for 32-bit compared to 64-bit?
- - By rocket (***) [se] Date 2017-11-14 15:52 Edited 2017-11-14 15:56
Suppose it takes on average 60 seconds for the 64-bit engine to solve a difficult position, what would be the equivalent time for the 32-bit to solve it?

Bitboard engine.
Parent - - By user923005 (****) [us] Date 2017-11-14 19:41
About twice as long if everything is actually using 32 bit integers for the 64 bit operations.
If the 64 bit operations are emulated using 32 bit integers, it takes twice as many operations.
Of course, the entire body of the program is not involved just in the bitboard operations.
But a lot of it is.

On the other hand, 32 bit code can sometimes take advantage of SSE type instructions.  So we really are using 64 bit operations on a 32 bit machine.
In such a case, the 32 bit code can be pretty close to the speed of the 64 bit code.

So, as a general rule of thumb, I would say that the speed of a 32 bit bitboard program will be between 50% and 75% of the speed of a 64 bit program.

So why would you use a 32 bit program in the first place?  Because you have a 32 bit operating system.  There is no other sensible reason that I can think of.
Parent - By rocket (***) [se] Date 2017-11-14 21:04
Are the elo differences lower in slow time controls?

My theory being that the slower 32-bit ponder time has enough to catch up with the faster one. So both pick the same moves under tournament time controls, only that the 32-bit took a bit longer.
Parent - By Peter Grayson (****) [us] Date 2017-11-14 22:46
The impact of hash table size must also be considered. Stockfish has a problem if more than 1Gb is allocated to its 32 bit engine usually indicating the engine has caused an exception.
Also if you play a MMX engine vs a Bitboard engine on a 32-bit computer, will the bitboard engine be at a greater disadvantage?

I found when I played an oldie Fritz vs Stockfish on 32-bit computers that Fritz scored quite a bit better (more draws). I have seen more draws in a fewer amount of games than in hundreds of games on the 64.bit computer. It can't be a coincidence.

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