From mboxrd@z Thu Jan 1 00:00:00 1970 From: Peter Clifton Subject: Re: FPS performance increase when deliberately spinning the CPU with an unrelated task Date: Tue, 26 Oct 2010 20:34:34 +0100 Message-ID: <1288121674.3597.12.camel@pcjc2lap> References: <1287835355.2578.26.camel@pcjc2lap> <87ocai6ndw.fsf@pollan.anholt.net> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from ppsw-50.csi.cam.ac.uk (ppsw-50.csi.cam.ac.uk [131.111.8.150]) by gabe.freedesktop.org (Postfix) with ESMTP id 1EABD9E744 for ; Tue, 26 Oct 2010 12:34:37 -0700 (PDT) Received: from cpc1-cmbg11-0-0-cust238.5-4.cable.virginmedia.com ([86.22.72.239]:54003 helo=[192.168.1.4]) by ppsw-50.csi.cam.ac.uk (smtp.hermes.cam.ac.uk [131.111.8.157]:465) with esmtpsa (LOGIN:pcjc2) (SSLv3:DHE-RSA-CAMELLIA256-SHA:256) id 1PApI3-00082X-rm (Exim 4.72) for intel-gfx@lists.freedesktop.org (return-path ); Tue, 26 Oct 2010 20:34:35 +0100 In-Reply-To: <87ocai6ndw.fsf@pollan.anholt.net> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: intel-gfx-bounces+gcfxdi-intel-gfx=m.gmane.org@lists.freedesktop.org Errors-To: intel-gfx-bounces+gcfxdi-intel-gfx=m.gmane.org@lists.freedesktop.org To: "intel-gfx@lists.freedesktop.org" List-Id: intel-gfx@lists.freedesktop.org On Mon, 2010-10-25 at 13:14 -0700, Eric Anholt wrote: I'm taking a bet on memory bandwidth being the constraint for fill limited applications. glxgears manages 59fps at full screen (minus title bar), which is 1680x1024, giving a pixel rate of approx 100Mpix/second (Ignoring over-fill) Assuming 2 bytes per pixel (ignoring possibility of depth / stencil writes), that is 200M bytes / second. Now I don't know what the likely memory bandwidth of the GMCH is, but I bet with scan out and other activity going on, we'll be pushing it quite hard to sustain that framerate. I'm targeting a desired ~15-20fps at nearly full-screen for my circuit board design app, so I will need to be careful with my code! This said, some top-range current cards from other manufacturers are claiming fill-rates in 10s of BILLIONS per second, and memory bandwidth of 10s up to ~100 GB/sec! (Although it comes with more than half the ram I have in this laptop, and probably costs about 1/2 - 3/4 what the laptop did). -- Peter Clifton Electrical Engineering Division, Engineering Department, University of Cambridge, 9, JJ Thomson Avenue, Cambridge CB3 0FA Tel: +44 (0)7729 980173 - (No signal in the lab!) Tel: +44 (0)1223 748328 - (Shared lab phone, ask for me)