From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261468AbVGLO2o (ORCPT ); Tue, 12 Jul 2005 10:28:44 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261463AbVGLO0v (ORCPT ); Tue, 12 Jul 2005 10:26:51 -0400 Received: from viper.oldcity.dca.net ([216.158.38.4]:7566 "HELO viper.oldcity.dca.net") by vger.kernel.org with SMTP id S261458AbVGLOZB (ORCPT ); Tue, 12 Jul 2005 10:25:01 -0400 Subject: Re: [PATCH] i386: Selectable Frequency of the Timer Interrupt From: Lee Revell To: "Martin J. Bligh" Cc: Chris Friesen , Diego Calleja , azarah@nosferatu.za.org, akpm@osdl.org, cw@f00f.org, linux-kernel@vger.kernel.org, torvalds@osdl.org, christoph@lameter.org In-Reply-To: <188690000.1121142633@[10.10.2.4]> References: <200506231828.j5NISlCe020350@hera.kernel.org> <20050708214908.GA31225@taniwha.stupidest.org> <20050708145953.0b2d8030.akpm@osdl.org> <1120928891.17184.10.camel@lycan.lan> <1120932991.6488.64.camel@mindpipe> <20050709203920.394e970d.diegocg@gmail.com> <1120934466.6488.77.camel@mindpipe> <176640000.1121107087@flay> <1121113532.2383.6.camel@mindpipe> <42D2D912.3090505@nortel.com> <1121128260.2632.12.camel@mindpipe> <165840000.1121141256@[10.10.2.4]> <1121141602.2632.31.camel@mindpipe> <188690000.1121142633@[10.10.2.4]> Content-Type: text/plain Date: Tue, 12 Jul 2005 10:24:59 -0400 Message-Id: <1121178300.2632.51.camel@mindpipe> Mime-Version: 1.0 X-Mailer: Evolution 2.2.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 2005-07-11 at 21:30 -0700, Martin J. Bligh wrote: > Exactly what problems > *does* it cause (in visible effect, not "timers are less granular"). > Jittery audio/video? How much worse is it? Yes, exactly. Say you need to deliver a frame of audio or video every 5ms. You have a rendering thread and a display thread that communicate via FIFOs. The main thread waits in select() for the next frame to complete rendering or for the deadline to expire. That's next to impossible with HZ=100, because the best you can do is the deadline +-10ms. With HZ=1000 it's no problem. Lee