From owner-freebsd-current@FreeBSD.ORG Tue Dec 20 08:43:06 2005 Return-Path: X-Original-To: freebsd-current@freebsd.org Delivered-To: freebsd-current@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 836F616A41F for ; Tue, 20 Dec 2005 08:43:06 +0000 (GMT) (envelope-from eta@lclark.edu) Received: from leguin.anholt.net (69-30-77-85.dq1sn.easystreet.com [69.30.77.85]) by mx1.FreeBSD.org (Postfix) with ESMTP id 73F2F43D55 for ; Tue, 20 Dec 2005 08:43:05 +0000 (GMT) (envelope-from eta@lclark.edu) Received: from leguin.anholt.net (localhost [127.0.0.1]) by leguin.anholt.net (8.13.4/8.13.1) with ESMTP id jBK8h4h7038109; Tue, 20 Dec 2005 00:43:04 -0800 (PST) (envelope-from eta@lclark.edu) Received: (from anholt@localhost) by leguin.anholt.net (8.13.4/8.13.1/Submit) id jBK8h3QC038108; Tue, 20 Dec 2005 00:43:03 -0800 (PST) (envelope-from eta@lclark.edu) X-Authentication-Warning: leguin.anholt.net: anholt set sender to eta@lclark.edu using -f From: Eric Anholt To: Jeremie Le Hen In-Reply-To: <20051220080632.GD3512@obiwan.tataz.chchile.org> References: <200512192117.jBJLHE8C057230@lurza.secnetix.de> <1135028917.75547.4.camel@leguin> <20051220080632.GD3512@obiwan.tataz.chchile.org> Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="=-btvCxRoMZuSayIPo8vIU" Date: Tue, 20 Dec 2005 00:43:02 -0800 Message-Id: <1135068182.75547.34.camel@leguin> Mime-Version: 1.0 X-Mailer: Evolution 2.4.2 FreeBSD GNOME Team Port Cc: freebsd-current@freebsd.org Subject: Re: [fbsd] Re: DRM update for testing X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Discussions about the use of FreeBSD-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 20 Dec 2005 08:43:06 -0000 --=-btvCxRoMZuSayIPo8vIU Content-Type: text/plain Content-Transfer-Encoding: quoted-printable On Tue, 2005-12-20 at 09:06 +0100, Jeremie Le Hen wrote: > Hi, Eric, >=20 > > glxgears is not a benchmark. >=20 > What benchmark do you advice ? Find an app whose performance you care about. Something that you would run regularly, and probably where the fps with hardware is approximately <=3D the refresh rate. For me that's been quake3, other developers ut2kX or doom3 or their own custom apps. Why is glxgears performance measurement pointless? 1) In software, many people see it going faster than the refresh rate. So why do you care if you can go 10x the refresh rate or only 1.5x? You're only displaying so much. 2) It's flat or smooth-shaded triangles. Does anybody use these? Well, some GL screensavers do, but those in particular I find work fine in software as well. 3) It's display lists of triangles. Most software where performance matters is going to be using some sort of vertex arrays of triangles (any game, basically) or lines (CAD, scientific apps). Those are going to be totally different rendering paths. 4) relative significance of swapping. In very few apps do you see swapping back to front (or perhaps waiting for pending swaps) being a major participant in the total time. Notably, 4) has led to bad optimizations like page flipping. It's a 20% or so performance improvement (over an existing 1000+ fps) in tests I've seen for glxgears, but I've only been able to measure .4% to 5% improvements for quake3 under rather ideal conditions. On the other hand, page flipping increases the complexity of your X driver code (it took a long time to get it to even render right), increases overhead of 2d operations to perform the extra accounting and copying, and is likely nonconformant for X drawing on top of GL drawing, which some apps will do as far as I've heard. That's what optimizing for bad benchmarks gets you. Oh, and for those using software, in software you're probably going to be measuring your CPU-framebuffer write speeds more than the-rest-of-GL speeds, anyway. Those rates are rather different between cards (notably, Intel stuff seems to do quite well with operations on framebuffer, perhaps due to its UMAness. I need to actually quantify it and see if I'm right), and it's unimportant for hardware acceleration. This is why I say that posting glxgears fps on mailing lists or IRC is just noise. That is, unless all you care about is the screensaver with the gears. --=20 Eric Anholt eta@lclark.edu http://people.freebsd.org/~anholt/ anholt@FreeBSD.org --=-btvCxRoMZuSayIPo8vIU Content-Type: application/pgp-signature; name=signature.asc Content-Description: This is a digitally signed message part -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.2 (FreeBSD) iD8DBQBDp8QWHUdvYGzw6vcRAmiZAKCNGXm4xu3cN+jKgBVI7db2dJPn6QCeJV25 PGuLMlsLaUUBXSIuxsgBzgg= =8rkB -----END PGP SIGNATURE----- --=-btvCxRoMZuSayIPo8vIU--