Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!swrinde!zaphod.mps.ohio-state.edu!think.com!snorkelwacker.mit.edu!bloom-picayune.mit.edu!athena.mit.edu!jfc From: jfc@athena.mit.edu (John F Carr) Newsgroups: comp.benchmarks Subject: Re: Don't use bc (was: More issues of benchmarking) Message-ID: <1990Dec8.051131.2289@athena.mit.edu> Date: 8 Dec 90 05:11:31 GMT References: <5042@taux01.nsc.com> Sender: news@athena.mit.edu (News system) Organization: Massachusetts Institute of Technology Lines: 22 >Today you have to benchmark the compiler as much as the hardware True: I noticed that dc for the IBM RT was compiled with pcc (the portable C compiler, which does only peephole optimization). I recompiled with a better compiler and the time for the test dropped from 45 seconds to 25 seconds. On a VAX, using gcc instead of pcc made about a 10% difference. The VAX 3 series and the IBM RT make an interesting comparison. DEC claims 4.9 MIPS for the faster versions of the VAX 3 (VAX 3100 model 38, VAX 3900). The RT is generally considered to be around 3-4 MIPS (Dhrystone v1 says 4.4). The "dc" benchmark (bc 2^5000/2^5000 pipes "2 5000^ 2 5000^/ps." to dc on BSD UNIX) runs twice as fast on a VAX 3900 when the best compilers available are used. On the other hand, a big number math package I've been using runs faster on the RT even though the VAX version is written in assebmly and the RT version in C. Floating point is usually faster on the VAX, but because the RT uses a 68881 coprocessor it does better on transcendental functions. Let me pick the benchmark and I'll demonstrate that my RT is faster than a DECstation 3100 (~12 MIPS). -- John Carr (jfc@athena.mit.edu)