Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!zaphod.mps.ohio-state.edu!wuarchive!udel!nigel.ee.udel.edu!mccalpin From: mccalpin@perelandra.cms.udel.edu (John D. McCalpin) Newsgroups: comp.benchmarks Subject: Re: Compilers & SPECmarks... Message-ID: Date: 8 Apr 91 18:27:43 GMT References: <32097@shamash.cdc.com> Sender: usenet@ee.udel.edu Followup-To: comp.arch Organization: College of Marine Studies, U. Del. Lines: 39 Nntp-Posting-Host: perelandra.cms.udel.edu In-reply-to: rrr@u02.svl.cdc.com's message of 8 Apr 91 17:02:48 GMT >> On 8 Apr 91 17:02:48 GMT, rrr@u02.svl.cdc.com (Rich Ragan) said: Rich> There has been discussion in the past about trying to separate Rich> out the effects of compilers from the underlying hardware performance. [......] Rich> The only thing we changed was to use a new FORTRAN compiler jointly Rich> developed with Kuck and Associates for the multi-processor CDC 4680. ----------------------------------------------------------------------------- gcc espr. li eqntott spice doduc nasa7 matrix fpppp tomcatv ----------------------------------------------------------------------------- Mips 6280 46.0 42.4 54.6 41.2 38.4 43.0 45.6 49.8 55.6 43.3 CDC 4680 46.0 42.4 54.6 41.2 40.3 44.0 62.4 181.7 56.5 57.5 ----------------------------------------------------------------------------- ^^^^^ I have worried about the inclusion of the 'matrix300' code in the SPEC suite, as it is such a simple calculation mathematically that it is possible that special compiler techniques can be used to greatly enhance the performance without necessarily helping the performance of more general codes. In this case, the LINPACK routines SGEMV, SGEMM, and SAXPY are used. It is well known that SGEMM can show very large improvements by hand-coding (I get a 33 MFLOPS vs 6 MFLOPS on my IBM RS/6000-320 by hand-coding), so an "SGEMM-recognizer" could short-circuit the usefulness of this benchmark considerably. Note that the new HP9000/730 gets a score of 273 on this test, which raises its SPEC floating-point rating considerably! This is not to suggest that Kuck & Associates did it this way, but the block-mode approach that is so helpful on matrix operations is of much more limited utility on more general array operations. P.S. Tell us more about the multiprocessor CDC 4680!!!! -- John D. McCalpin mccalpin@perelandra.cms.udel.edu Assistant Professor mccalpin@brahms.udel.edu College of Marine Studies, U. Del. J.MCCALPIN/OMNET