From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S266381AbUGJUOk (ORCPT ); Sat, 10 Jul 2004 16:14:40 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S266386AbUGJUOk (ORCPT ); Sat, 10 Jul 2004 16:14:40 -0400 Received: from roc-24-93-20-125.rochester.rr.com ([24.93.20.125]:5110 "EHLO mail.kroptech.com") by vger.kernel.org with ESMTP id S266381AbUGJUO0 (ORCPT ); Sat, 10 Jul 2004 16:14:26 -0400 Message-ID: <099101c466ba$7d75aa30$03c8a8c0@kroptech.com> From: "Adam Kropelin" To: "Dmitry Torokhov" , Cc: "Tim Bird" , "CE Linux Developers List" , "Todd Poynor" , "Geert Uytterhoeven" References: <40EEF10F.1030404@am.sony.com> <20040710115413.A31260@mail.kroptech.com> <20040710142800.A5093@mail.kroptech.com> <200407101319.31147.dtor_core@ameritech.net> Subject: Re: [PATCH] preset loops_per_jiffy for faster booting Date: Sat, 10 Jul 2004 16:14:22 -0400 MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2800.1409 X-MIMEOLE: Produced By Microsoft MimeOLE V6.00.2800.1409 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Dmitry Torokhov wrote: > On Saturday 10 July 2004 01:28 pm, Adam Kropelin wrote: >> + Note that on SMP systems the preset will be applied to all CPUs >> + which will cause problems if for some reason your CPUs need >> + significantly divergent settings. >> + >> + If unsure, set this to 0. An incorrect value will cause delays in >> + the kernel to be wrong, leading to unpredictable I/O errors and >> + other breakage. Although unlikely, in the extreme case this might >> + damage your hardware. > > Note that it may also not work correctly on laptops that switch > frequency when working on battery/AC. Also one needs to be careful > when changing timesource (pit, tsc, pm, hpet). And always look out > for timer code changes in next version of kernel. Certainly many demons lurk around the corner, but embedded guys are used to that. > Does 250 ms worth all this pain? On a desktop box, almost certainly not. On a massive SMP machine, maybe. On an embedded system that is required to boot in a ridiculously short time, absolutely. --Adam