From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261235AbUL1V72 (ORCPT ); Tue, 28 Dec 2004 16:59:28 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261262AbUL1V72 (ORCPT ); Tue, 28 Dec 2004 16:59:28 -0500 Received: from viper.oldcity.dca.net ([216.158.38.4]:6317 "HELO viper.oldcity.dca.net") by vger.kernel.org with SMTP id S261235AbUL1V7Z (ORCPT ); Tue, 28 Dec 2004 16:59:25 -0500 Subject: Re: Real-time rw-locks (Re: [patch] Real-Time Preemption, -RT-2.6.10-rc2-mm3-V0.7.32-15) From: Lee Revell To: Bill Huey Cc: Steven Rostedt , Esben Nielsen , Ingo Molnar , Rui Nuno Capela , "K.R. Foley" , Fernando Lopez-Lezcano , Mark Johnson , Amit Shah , Karsten Wiese , Adam Heath , emann@mrv.com, Gunther Persoons , LKML , Florian Schmidt , Shane Shrybman , Thomas Gleixner , Michal Schmidt In-Reply-To: <20041227210614.GA11052@nietzsche.lynx.com> References: <1104165560.20042.108.camel@localhost.localdomain> <20041227210614.GA11052@nietzsche.lynx.com> Content-Type: text/plain Date: Tue, 28 Dec 2004 16:59:23 -0500 Message-Id: <1104271163.20714.44.camel@krustophenia.net> Mime-Version: 1.0 X-Mailer: Evolution 2.0.3 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 2004-12-27 at 13:06 -0800, Bill Huey wrote: > I was just having a discussion about this last night with a friend > of mine and I'm going to pose this question to you and others. > > Is a real-time enabled kernel still relevant for high performance > video even with GPUs being as fast as they are these days ? > > The context that I'm working with is that I was told (been out of > gaming for a long time now) that GPus are so fast these days that > shortage of frame rate isn't a problem any more. An RTOS would be > able to deliver a data/instructions to the GPU under a much tighter > time period and could delivery better, more consistent frame rates. > > Does this assertion still apply or not ? why ? (for either answer) Yes, an RTOS certainly helps. Otherwise you cannot guarantee a minimum frame rate - if a long running disk ISR fires then you are screwed, because jsut as with low latency audio you have a SCHED_FIFO userspace process that is feeding data to the GPU at a constant rate. Its a worse problem with audio because you absolutely cannot drop a frame or you will hear it. With video it's likely to be imperceptible. Lee