Path: utzoo!utgpu!jarvis.csri.toronto.edu!cs.utexas.edu!uunet!jarthur!uci-ics!rfg From: rfg@ics.uci.edu (Ronald Guilmette) Newsgroups: comp.sys.m88k Subject: Re: DG's use of m88k Message-ID: <25EA4069.17611@paris.ics.uci.edu> Date: 27 Feb 90 08:55:05 GMT References: <7521@imag.imag.fr> <36461@mips.mips.COM> Reply-To: rfg@ics.uci.edu (Ronald Guilmette) Organization: UC Irvine Department of ICS Lines: 40 In article <36461@mips.mips.COM> mash@mips.COM (John Mashey) writes: > >All these criticisms are well-taken, althought the programs are either >real ones, or derived kernels from real ones where the bulk of the time is >spent in small loops (that's the way many scientific codes really are). If individual program are measuring for "scientific" performance, they should probably be labeled as such. Now that I got thah off my chest, I'd like to ask a question about the GCC member of the SPEC suite. It is my understanding that GCC spends a great deal of its time doing code generation and/or optimization. Obviously, the actual amount of time spent doing these things can (potentially) vary a great deal depending upon the target machine that you are having GCC generate code for. Therefore, it would seem that in order to obtain a really "fair" apples-to-apples comparison of performance using GCC as a test case, you would have to run GCC on host machine X and have it compile some code for target machine Z and then run GCC hosted on machine Y and again have it produce code targeted for the same target machine (Z) as in previous tests. I'd just like to know if this is in fact what happens when the GCC "benchmark" is evaluated as part of SPEC benchmarking. Is that how it is done, or do the benchmarkers run GCC hosted on X and targeted for X and then run GCC hosted on Y and targeted for Y? If so, that seems to be a possible source of misleading information. Of course, some people might say that the cost of compiling for a particular machine *should* be factored in as a part of the overall "performance" of the machine itself. Perhaps that's true, but again it may be a question of properly "labeling" the results so that people who read the SPEC numbers fully understand that compilation speed FOR THAT MACHINE was factored in. (People who do no software development will not care about this factor at all, but conversly, professional software developers might care about that particular performance factor above all else). // Ron Guilmette (rfg@ics.uci.edu) // C++ Entomologist // Motto: If it sticks, force it. If it breaks, it needed replacing anyway.