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 XAA07304; Fri, 13 Jun 2003 23:56:23 +0200 (MET DST) X-Authentication-Warning: pauillac.inria.fr: majordomo set sender to owner-caml-list@pauillac.inria.fr using -f Received: from concorde.inria.fr (concorde.inria.fr [192.93.2.39]) by pauillac.inria.fr (8.7.6/8.7.3) with ESMTP id XAA06826 for ; Fri, 13 Jun 2003 23:56:22 +0200 (MET DST) Received: from bluejay.mail.pas.earthlink.net (bluejay.mail.pas.earthlink.net [207.217.120.218]) by concorde.inria.fr (8.11.1/8.11.1) with ESMTP id h5DLuLH06171 for ; Fri, 13 Jun 2003 23:56:21 +0200 (MET DST) Received: from tcsndslgw9poolf147.tcsn.uswest.net ([67.41.20.147] helo=dylan) by bluejay.mail.pas.earthlink.net with asmtp (Exim 3.33 #1) id 19QwWx-0002rI-00 for caml-list@inria.fr; Fri, 13 Jun 2003 14:56:19 -0700 Message-ID: <00e901c331f6$b364a820$0201a8c0@dylan> From: "David McClain" To: References: Subject: Re: [Caml-list] FP's and HyperThreading Processors Date: Fri, 13 Jun 2003 14:56:52 -0700 MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2800.1158 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1165 X-ELNK-Trace: 7a0ab3eafc8cf994b22988ad1c62733440683398e744b8a4947c00b56798c134d5c2ccc048b6fd87a2d4e88014a4647c350badd9bab72f9c350badd9bab72f9c X-Spam: no; 0.00; mcclain:01 dmcclain:01 caml-list:01 althought:01 optical:99 numbering:01 threads:01 pci:99 arrays:01 ocaml:01 flush:01 ought:01 routines:02 budget:97 fortran:03 Sender: owner-caml-list@pauillac.inria.fr Precedence: bulk > Althought he FFT code itself probably has large influence on memory access > patterns. Yes! Good point! My FFT's in the optical code are all rather large'ish 2-D FFT's (numbering 256x256 on average). The vendor supplied code is a 1-D FFT wrapped by a hand coded C orchestrator to split these large 2-D arrays into multiple threads of concurrent 1-D FFT's. But the sheer size of these arrays will most likely flush the cache of anything needed by the higher level OCaml analysis routines. This machine is a consumer grade P4 and so it still incorporates a PCI bus, and the cache is probably minimally sized. Such is the cost of doing science on a shoestring budget.... But I ought not complain... I have a machine on my desk with nearly 10^6 as much memory, and a thousand times faster, than I once had, and I don't have to wait around all day for the printed program output from my tray of cards representing a Fortran program... - DM ------------------- 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