Author: Eugene Nalimov
Date: 14:04:11 11/27/99
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On November 27, 1999 at 08:59:51, Vincent Diepeveen wrote: >On November 27, 1999 at 04:16:53, blass uri wrote: > >>Does someone know about a book about the fastest C program to do simple tasks? >>(for example to find if a number is a prime) > >>I think that knowing this information can help to think about ideas how to do >>chess programs faster. > >Let's please distinguish two things > - used algorithm > - used implementation > >You can make a very good optimized program A to generate primes, >but a silly implemented other program B might generate at the same >hardware a lot faster primes using a better algorithm. > >In general people then say that program A sucks and that a program B is >wonderful... ...yet from programming viewpoint this is rather hard to do. > >>I understand that +- operations are faster than */ operations but I do not know >>how much faster and if it is dependent on the computer. > >That depends upon architecture. >Multiply is in general not slower than incrementing with a register. >I'm using a lot of multiples in my DIEP's eval. > >At the P5 it sure is very slow. At the PRO/PII/PIII/Xeon it isn't. >Don't know about the K7, but i bet it's not slower there either, as >DIEP runs 15.5% faster on a K7 than on a PIII at the same Mhz. > >>Where can I get information like this information? > >www.intel.com > >Go to the technical references of the CPUs. >K7 is harder. > >>I can find it by doing a simple program but I prefer not to check everything >>about speed by testing because I may have many question like this question. >>Uri > >Rather hard to find it by doing a simple program, measuring things >accurately is also an art in itselve. > >What is however slowing down programs most is not the clocks needed to >do an integer multiplication. The real problem are branches. At the >Merced this should all be solved, so i wonder why the first vague reports >about the merced don't say it to be a lot faster than the 21264 cpu. Yes, but at IA-64 multiplication is *very* slow. Eugene
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