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 VAA21718; Tue, 8 Jun 2004 21:16:13 +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 VAA21608 for ; Tue, 8 Jun 2004 21:16:12 +0200 (MET DST) Received: from outbound28-2.lax.untd.com (outbound28-2.lax.untd.com [64.136.28.160]) by concorde.inria.fr (8.12.10/8.12.10) with SMTP id i58JGASH004485 for ; Tue, 8 Jun 2004 21:16:10 +0200 Received: from outbound28-2.lax.untd.com (smtp01.lax.untd.com [10.130.24.121]) by smtpout04.lax.untd.com with SMTP id AABANNEB4ATYQDFA for (sender ); Tue, 8 Jun 2004 12:15:06 -0700 (PDT) Received: (qmail 3159 invoked from network); 8 Jun 2004 19:14:31 -0000 Received: from 66-52-245-36.sttl.dial.netzero.com (HELO vangogh) (66.52.245.36) by smtp01.lax.untd.com with SMTP; 8 Jun 2004 19:14:31 -0000 From: "Brandon J. Van Every" To: "caml" Subject: RE: [Caml-list] 32 bit floats, SSE instructions Date: Tue, 8 Jun 2004 12:24:15 -0700 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset="Windows-1252" Content-Transfer-Encoding: 7bit X-Priority: 3 (Normal) X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook IMO, Build 9.0.6604 (9.0.2911.0) In-Reply-To: <200406081810.52526.jdh30@cam.ac.uk> X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1409 Importance: Normal X-ContentStamp: 16:8:2837093689 X-UNTD-OriginStamp: CI84cOLHFqh7Zd2QWkwvEFvwyO3T/pIsPQZphDk9MRhlu4bcjcrD1+MKGm/bvMfM X-Miltered: at concorde with ID 40C6107A.000 by Joe's j-chkmail (http://j-chkmail.ensmp.fr)! X-Loop: caml-list@inria.fr X-Spam: no; 0.00; brandon:99 caml-list:01 floats:01 brandon:99 hardcoded:01 model:01 apis:01 era:99 mentality:01 shaders:01 'only':99 seattle:99 crappy:01 2004:99 routines:02 Sender: owner-caml-list@pauillac.inria.fr Precedence: bulk Jon Harrop > Brandon J. Van Every wrote: > > [SoA is performed] > > At the cost of inverting almost everyone's software architecture. > > If you've hardcoded your routines to a particular way of > accessing memory then > that's hardly INRIA's fault. Even if it is with C macros, you > should have > structured your code so that your data structures could be > changed later. What utter nonsense! You ever written a 3D device driver? You do *not* engineer your most basic data structures for infinite flexibility. Almost nobody has the luxury of defining things so abastractly that they can switch SoA for AoS whenever they like. It's a highly invasive change of programming model. The experiment of SoA has been tried in the 3D graphics industry and found wanting. All the HW is AoS. The SoA methodology is possible with the 3D APIs. As one poster hinted, it's probably borne of the software rendering era mentality. I distinctly recall when the DirectX 5.0 guys were implementing those features, shortly after the OpenGL guys did IIRC. That would have been a 1997 timeframe. They were thinking how "neat" it would all be. Seen from the vantage of 2004, it all gave way to AoS and programmable shaders. All your data for one vertex or one pixel at a time. > Storing a matrix in transpose format is hardly going to > "destroy" coherence. > > The only algorithms which would be significantly affected are > those for which > accesses are to (x_i, y_i, z_i) for random "i" rather than to Oh, the 'only' algorithms. Crikey. You ever written a 3D graphics pipeline??? You think it's all based on handing over some huge matrix that could jolly well be in whatever order? Get real. The vast majority of 3D graphics processing is accept / reject testing. You want your data here, now, so you can decide what to do with it. So you can retire it once you're done deciding, and not have it pollute your cache any further. Cheers, www.indiegamedesign.com Brandon Van Every Seattle, WA "We live in a world of very bright people building crappy software with total shit for tools and process." - Ed Mckenzie --- Outgoing mail is certified Virus Free. Checked by AVG anti-virus system (http://www.grisoft.com). Version: 6.0.693 / Virus Database: 454 - Release Date: 5/31/2004 ------------------- 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