From mboxrd@z Thu Jan 1 00:00:00 1970 Received: (from majordomo@localhost) by pauillac.inria.fr (8.7.6/8.7.3) id EAA21100; Fri, 2 Aug 2002 04:56:29 +0200 (MET DST) X-Authentication-Warning: pauillac.inria.fr: majordomo set sender to owner-caml-list@pauillac.inria.fr using -f Received: from nez-perce.inria.fr (nez-perce.inria.fr [192.93.2.78]) by pauillac.inria.fr (8.7.6/8.7.3) with ESMTP id EAA21072 for ; Fri, 2 Aug 2002 04:56:28 +0200 (MET DST) Received: from ext-ch1gw-2.online-age.net (ext-ch1gw-2.online-age.net [216.34.191.36]) by nez-perce.inria.fr (8.11.1/8.11.1) with ESMTP id g722uRr09058 for ; Fri, 2 Aug 2002 04:56:27 +0200 (MET DST) Received: from int-ch1gw-2.online-age.net (int-ch1gw-2 [3.159.232.66]) by ext-ch1gw-2.online-age.net (8.12.3/8.9.1/990426-RLH) with ESMTP id g722uQEN011270; Thu, 1 Aug 2002 22:56:26 -0400 (EDT) Received: from uswaumsxb4medge.med.ge.com (localhost [127.0.0.1]) by int-ch1gw-2.online-age.net (8.12.3/8.12.3/990426-RLH) with ESMTP id g722uKoL022186; Thu, 1 Aug 2002 22:56:20 -0400 (EDT) Received: by USWAUMSXB4MEDGE with Internet Mail Service (5.5.2656.59) id ; Thu, 1 Aug 2002 21:56:09 -0500 Message-ID: From: "Gurr, David (MED, self)" To: Noel Welsh Cc: caml-list@inria.fr Subject: RE: ocaml, simd, & fftwgel RE: [Caml-list] Caml productivity. Date: Thu, 1 Aug 2002 21:56:09 -0500 MIME-Version: 1.0 X-Mailer: Internet Mail Service (5.5.2656.59) Content-Type: text/plain Sender: owner-caml-list@pauillac.inria.fr Precedence: bulk Noel Welsh: > There are a least two parallelising C compilers for > the PC: Intel's and CodePlay's. CodePlay say they do > a better job than Intel. I imagine Intel hold a > differing opinion. But do they do a better job than fftwgel or Spiral or Atlas? > I'm interested in knowing the deficiencies of these > compilers. I imagine they run into problems with > dependency analysis on complicated array expressions. > Similarly, I'm interested in knowing in what areas HPF > and SAC are performant. It appears to me that a > functional language (where dependency analysis is > simple) with array shape inference should be capable > of creating very array fast code is almost all > situations (and the SAC benchmarks show them beating > HPF). Is SAC available for public inspection? > > Cheers, > Noel I have not used either compiler. From the FFTW, Atlas, etc experience the only way to get consistently high performance from a C compiler is to do most of the work for the compiler and carefully feed it code that it correctly optimizes. This is a compiler and application specific trial and error process. FFTW does the optimization and scheduling for the C compiler. Once you do this, it is much less clear what the value added of the C compiler is. In particular, the amount of refinement that would be needed to get ocamlopt to match C compilers at this task might be relatively small. I have not read to code to fftwgel but if fftwgel could be married to ocamlopt, they might well produce code superior to intel or codeplay since C is notoriously difficult to optimize even without SIMD. -D ------------------- To unsubscribe, mail caml-list-request@inria.fr Archives: http://caml.inria.fr Bug reports: http://caml.inria.fr/bin/caml-bugs FAQ: http://caml.inria.fr/FAQ/ Beginner's list: http://groups.yahoo.com/group/ocaml_beginners