From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S262674AbTLLXje (ORCPT ); Fri, 12 Dec 2003 18:39:34 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S262694AbTLLXje (ORCPT ); Fri, 12 Dec 2003 18:39:34 -0500 Received: from gprs149-168.eurotel.cz ([160.218.149.168]:6531 "EHLO amd.ucw.cz") by vger.kernel.org with ESMTP id S262674AbTLLXjc (ORCPT ); Fri, 12 Dec 2003 18:39:32 -0500 Date: Sat, 13 Dec 2003 00:40:29 +0100 From: Pavel Machek To: Jean-Marc Valin Cc: "Martin J. Bligh" , Linux Kernel Subject: Re: Increasing HZ (patch for HZ > 1000) Message-ID: <20031212234028.GA541@elf.ucw.cz> References: <1071126929.5149.24.camel@idefix.homelinux.org> <1293500000.1071127099@[10.10.2.4]> <20031212220853.GA314@elf.ucw.cz> <1071269849.4182.14.camel@idefix.homelinux.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1071269849.4182.14.camel@idefix.homelinux.org> X-Warning: Reading this can be dangerous to your mental health. User-Agent: Mutt/1.5.4i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Hi! > > Every notebook from thinkpad 560X up has produced some kind of > > cpu-load-related-noise. You'd have to throw out quite a lot of > > notebooks... > > You're right, I'm probably not the only one. It may be worth at least > having an option to change HZ to less annoying values. Otherwise there > are going to be lots of complaints when people try out 2.6 on their > laptops and hear that noise. On mine, I seriously could not stand the > noise more than 5 minutes. Not because it was that loud but 1 kHz is > really annoying. Okay, we are probably taking other sounds. I can hear cpu-load-related noise on every notebook from thinkpad 560X -- in a quiet room, and on some machines its rather hard to notice. You probably have way more annoying problem. > > PS: Jean, can you try how high you can get it? You might want to go to > > 24kHz so that no human can hear it, or to 100kHz to be kind to > > cats. At ~1MHz you'd be even kind to bats :-), but it is probably > > impossible to get over 200kHz or so. Still it might be funny > > experiment. > > For now, my patch only allows up to around 10 kHz. At that frequency, I > don't hear anything because the noise is not loud enough (ear is much > more sensitive at 1 kHz). Also, I have around 10% overhead on my > Pentium-M 1.6 GHz, so I guess it's not for everyone. Extrapolating from > there, I'd also say that at 100 kHz, it wouldn't do anything but handle > the interrupts, which is slightly annoying when you want to actually get > some work done :) I wonder what happens at 200kHz then; system might detect some lost ticks and keep running at very slow speed... Pavel -- When do you have a heart between your knees? [Johanka's followup: and *two* hearts?]