From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1750817AbWFSBwl (ORCPT ); Sun, 18 Jun 2006 21:52:41 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1750937AbWFSBwl (ORCPT ); Sun, 18 Jun 2006 21:52:41 -0400 Received: from mail24.syd.optusnet.com.au ([211.29.133.165]:39873 "EHLO mail24.syd.optusnet.com.au") by vger.kernel.org with ESMTP id S1750888AbWFSBwk (ORCPT ); Sun, 18 Jun 2006 21:52:40 -0400 From: Con Kolivas To: Lee Revell Subject: Re: [ckpatch][15/29] hz-no_default_250.patch Date: Mon, 19 Jun 2006 11:52:27 +1000 User-Agent: KMail/1.9.3 Cc: Albert Cahalan , linux-kernel@vger.kernel.org, john stultz References: <787b0d920606181752j4b7c7309t9c0ab9bf8da1537a@mail.gmail.com> <1150680632.4428.129.camel@mindpipe> In-Reply-To: <1150680632.4428.129.camel@mindpipe> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200606191152.28038.kernel@kolivas.org> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Monday 19 June 2006 11:30, Lee Revell wrote: > On Sun, 2006-06-18 at 20:52 -0400, Albert Cahalan wrote: > > > Make 250 HZ a value that is not selected by default and give some > > > better recommendations in help. > > > > No, 250 is a good default. > > > > We can't reliably do 1000. There are many systems, including both > > laptops and servers, which have a BIOS that uses SMM/SMI to grab > > the CPU for longer than a millisecond. We'd lose clock ticks if > > we had HZ at 1000. > > Doesn't this become a non-issue with John Stultz's gettimeofday rework? No, but Thomas Gleixner's HRTimers will. Also the extra granularity in the cpu scheduler is desirable on a desktop. > > > NTSC video is 59.94 fields per second. Though a sample rate of > > double that would satisfy the Nyquest theory, in practice you > > need to go to 4x to 5x the rate you want. This comes out to be > > around 240 to 300 as a minimum. > > Realtime audio wants higher framerates than video. Of course many of > these systems with the SMM bug are fatally broken for these > applications. Agreed. -- -ck