Author: Eugene Nalimov
Date: 12:31:02 04/20/02
Go up one level in this thread
I would not tell "However to all standards, programming of DIEP is very professionally done" about the programmer who needlessly duplicates tens of megabytes of data only because he did not figured out how to efficiently use threads instead of processes. Or about the programmer who included others' code into his program without the permission. Eugene On April 20, 2002 at 10:14:09, Vincent Diepeveen wrote: >It has been some years that a compiler beated microsoft >dominated software, so that's why i post here the result i had >after a week of experimentations with intel c++. > >Intel(R) C++ Compiler for 32-bit applications, Version 5.0.1 Build 010525Z >Copyright (C) 1985-2001 Intel Corporation. All rights reserved. >icl: NOTE: You have 17 days left in your evaluation period. >icl: Command line error: no files specified; for help type "icl -help" > >Hardware used: > diep compiled single cpu run at dual K7 MP 1.2Ghz > Using P4s in this respect is utter nonsense, because at the > moment and in the coming future the K7 cpu will dominate > for computerchess the different tournaments. apart from that > they are also cheaper than P4 (not so important argument though), > and no matter how hard compiler teams work, the 8KB L1 datacache > from the P4 is such a big weak chain that their work will be > useless, right now the K7 is more than 70% faster than the P4 > (both at the same clockrate). Only bad programmed software you > might get 70% or more speedup (or in a language that's very > inefficient such as fortran). Getting 70% out of my software > must be seen as impossible. > >Comparision with msvc 6.0 sp4 + processor pack (at least 2% faster >than any other m$ product which one can buy in a shop). > > VERIFICATION > >Many options i tried and i found out that the P4 optimizations, >appear to have major bugs. This can also be caused because i run >my software on a K7 MP cpu, the competitor from the P4. >K7 cpu's aren't holy at all. I don't >doubt the K7 cpu's has more bugs than for example a P3 cpu has, >but no doubt the P4 optimizations use ways to optimize code which >are simply not legal at K7 cpu's, or they simply contain bugs. > >Several other options i also found having bugs. > >The first important thing of a compiler is that it produces RELIABLE >output. As mentionned above this is not the case with intel c++ with >all strings used. If their argument is that i should not use things >like 'IP optimizations' to produce correct code, then i would like to >see that in their documentation. It is not there though, but well >it's an EVALAUTION version, so let's not complain too loud, as >i managed to find options which did produce quick and correct code. > >Default compile from intel c++ is very quickly producing an executable >which is about 0.5% slower. > >However as ultimate speedfreak i'm more interested in the maximum speed >i can get out of it. So First thing to do was: > >CFLAGS = -O3 -G6 -Qaxi -Qxi -Gr -Qprof_genx > >That produces an executable which i ran for several minutes. > >then i removed the object files and recompile with: > >CFLAGS = -O3 -G6 -Qaxi -Qxi -Gr -Qprof_use > >Now the executable is 3.5% faster than a quick compile with -O2 -G6 with >the msvc compiler. > >SO MSVC FINALLY BEATEN!!!! > >I assume they are beaten till they release at the end of this year >a new version of msvc, which is still a LONG TIME to go. > >The interesting thing is that msvc gets beaten at a CPU manufactured >by the competitor of the company that produces the compiler that >is doing so well. > > A PROFESSIONAL 3.5% > >How much is 3.5%? That's a very good question. If i upgrade my K7 >from 1.2Ghz to 1.4Ghz then i get a bit more than 10% faster. However >to all standards, programming of DIEP is very professionally done, >when compared to most software that's in specint testsets for example. >3.5% is a nearly impossible to get speedup by software rewrites. >Rewriting megabytes of >source code i still doubt i would get it. Only programming DIEP >in assembly (it's completely C code with only locking done inline >in assembly, note that this compile doesn't use any inline assembly >as it's the single cpu version) it is possible to get more than 3.5% >speedup i guess. > >By any standard of well programmed software, 3.5% is a *major* speedup.
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