Author: Vincent Diepeveen
Date: 14:33:55 12/21/02
Go up one level in this thread
On December 21, 2002 at 01:21:23, Matt Taylor wrote: >On December 20, 2002 at 16:43:20, Vincent Diepeveen wrote: > >>On December 19, 2002 at 16:21:19, Matt Taylor wrote: >> >>>On December 19, 2002 at 12:31:15, Robert Hyatt wrote: >>> >>>>On December 19, 2002 at 12:00:32, Vincent Diepeveen wrote: >>>> >>>>>On December 19, 2002 at 11:43:22, Robert Hyatt wrote: >>>>> >>>>>>On December 19, 2002 at 09:43:54, Vincent Diepeveen wrote: >>>>>> >>>>>>>On December 19, 2002 at 07:53:32, Frederic Louguet wrote: >>>>>>> >>>>>>>>My program Chess Wizard has always run much faster on Athlon than on P4, but >>>>>>>>maybe using default optimizations is not enough. So I have a question for >>>>>>>>compiler gurus : what are the best compiler optimizations you can use under >>>>>>>>Microsoft Visual C++ 6.0 with processor pack, running under Windows XP, for >>>>>>>>Athlon XP/MP and for Pentium 4. >>>>>>>> >>>>>>>>Before I try everything myself, maybe someone has made experiments and has >>>>>>>>interesting results to share ? >>>>>>> >>>>>>>Yes. >>>>>>> >>>>>>>Try mingw with msys. >>>>>>>it works under windows. >>>>>>> >>>>>>>download the latest gcc compiler. >>>>>>>then compile a version with profile info. produce profile >>>>>>>info. then recompile with that and branches get optimized. >>>>>>> >>>>>>>should get your chess wizard, assuming it's a non-bitboard (gcc >>>>>>>is horrible optimizing 64 bits code for 32 bits processors), a lot >>>>>>>faster. >>>>>>> >>>>>>>It sure works for diep very fast. >>>>>> >>>>>> >>>>>>Also he should try the Intel C/C++ compiler v 7.0 download from Intel's >>>>>>web site. It produces faster code for me than any version of gcc that is >>>>>>available. >>>>> >>>>>you have a P4. he has an AMD K7. I bet even old visual c++ 6.0 sp4 procpack >>>>>beats the intel 7.0 on that hardware ;) >>>> >>>> >>>>I suppose that is the _big_ difference between us. I prefer to _test_ and >>>>produce data that can be used to make a decision. Rather than "guesswork". >>> >>>The least he could do is read the optimization manuals and make a clever >>>observation. You might as well call the Athlon optimization manual the P4 Jr. >>>optimization manual. The bulk of the manuals are identical concepts with >>>different wording and style. >>> >>>I have seen a number of tests which pretty much confirm that P4-optimized code >>>is going to fly on Athlon, too. It won't be *best* on Athlon, but it's going to >>>beat Visual C++ 6.0 SP4 with Processor Pack. When you think about it, it makes >>>sense, too. All superscalar processors are suffering mostly from the same >>>effects. >>> >>>-Matt >> >>Bob is wrong about the guess work. Testing shows simply that at athlon K7 >>DIEP is a lot faster with gcc with fbranch-probabilities, than it is with >>intel c++ (of course not even counting bugs in the code intel c++ >>generates). >> >>Your assumption is wrong too. With regard to single cpu applications >>(and specint which includes crafty is run single cpu as far as i know) >>the P4 and the P3 and the K7 are not much different from the old PentiumPro. >> >>The weak chain of the pentiumpro and the PII definitely came back into the >>K7 and the P4. The weak chain being clearly branches (i am not using >>64 bits bitboards so all these problems crafty has i do not have with >>that vector instructions might be faster or slower in some way). >> >>The penalty for branches at the P6 and P2 were already so huge in 1996, >>that by now in 2002, every chessprogrammer who did a lot of optimization >>work, definitely optimized this a lot. >> >>It is a gross misunderstanding guessing that i could change lossless >>something with regard to single cpu DIEP to get it faster at the P4. >> >>Add to that, that the P4 optimizations from the intel compiler do not >>seem to run on the K7 at all, apart from that they generate bugs. >> >>Blaming that onto the K7 is no good idea. 50% of the computerchess users >>at least have a K7. If something is broken, then work around it, don't >>blame it on a processor. > >Or the fact that the K7 and P7 do not completely share the same instruction set. > >>Yet the intel c++ lemma seems to be that the specint number must be increased. >>Rest of world can drop dead from them seemingly when they can win 0.01% for >>that goal. >> >>intel c++ 6.0 or 7.0 optimized executables will *never* run fast on K7 >>when compared to speed other compilers or old 5.0 generates for it. > >Ironic that. I've run Intel C 6/7 binaries on my dual-K7. They work fine. >They're faster than their gcc equivalents. I'm really not sure what you're >talking about since my experiences have been quite good. > >-Matt You gotta be running bitboard programs or not use gcc 3.2.1 or whatever. For diep gcc 3.2.1 is 20% faster than intel c++ 6.0. Of course at a K7. Not at the P4. i do not doubt intel c++ is fast for the P4 and producing code that by 'accident' runs slow on k7. also default msvc sp4 procpack compiles are all faster than intel c++ 6.0 compiles for K7. didn't try version 7 yet but i am a realistic man. i know who i would fire when as a manager at intel my guys would make something that let the K7 look like better than the P4. Best regards, Vincent
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