Author: Mike Byrne
Date: 12:17:30 12/31/02
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On December 31, 2002 at 11:49:37, Uri Blass wrote: >1)I read in the intel tutorial that I can use optimization like loop >optimization. >Does it mean that it is always better to change my project option from 02 to 03 >and if it is the case why not using 03 as the default option? > >2)I read that G7 is the default option but for some reason I see GX in my >computer. >What does it mean? > >The following table was copied and edited by me from the intel tutorial > > Option Setting Processor >Windows* Linux* > >-G6 -tpp6 Pentium Pro, Pentium II and Pentium III processors > >-G7 default -tpp7 default Pentium 4 processor > > >tpp7 is for linux and it is not relevant for me. >I expected to see G7 in my project option and not GX and I am afraid to change >the X. > >3)From reading the tutorial I get the impression that I cannot give a version >that is the best for all processors and the only way to get a version that is >best for all processors is to have 4 different exe files when everyone of them >run only on specific processors. > >The following is copied from intel's totorial > >"Because they contain multiple versions of code, applications compiled with >these options have increased code size. However, the performance of such code is >better than standard optimized code, although slightly slower than code compiled >with the -Qx[i|M|K|W] options," > >How much is slightly slower for chess programs and is there a way to avoid the >problem(for some reason I do not see programmers release 4 different version >when they ask the user to choose based on the processor)? > >Uri It's a tad slower. In most programs, you would never notice. When I looked it with Intel 6.0 it was about 2% - for chess programmers that's HUGE. Use the -Qax[i|M|K|W] for compatiblility. On Intel 6.0, I actually found some of the optimizations for older processors faster for Crafty even on newer processors. I think it dealt with how they handled Integers. On Intel 7, I believe the newer optimazations (P4) are actually faster for P4's based on some tests I ran. Michael
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