From owner-freebsd-questions@FreeBSD.ORG Mon Jul 2 12:11:42 2007 Return-Path: X-Original-To: freebsd-questions@freebsd.org Delivered-To: freebsd-questions@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [69.147.83.52]) by hub.freebsd.org (Postfix) with ESMTP id D42CB16A421 for ; Mon, 2 Jul 2007 12:11:42 +0000 (UTC) (envelope-from cpghost@cordula.ws) Received: from fw.farid-hajji.net (fw.farid-hajji.net [213.146.115.42]) by mx1.freebsd.org (Postfix) with ESMTP id 5BE6013C4AD for ; Mon, 2 Jul 2007 12:11:42 +0000 (UTC) (envelope-from cpghost@cordula.ws) Received: from epia-2.farid-hajji.net (epia-2 [192.168.254.11]) by fw.farid-hajji.net (Postfix) with ESMTP id 654C5DFC2C; Mon, 2 Jul 2007 14:11:46 +0200 (CEST) Message-ID: <4688EBF4.8040409@cordula.ws> Date: Mon, 02 Jul 2007 14:13:40 +0200 From: cpghost User-Agent: Thunderbird 2.0.0.4 (X11/20070616) MIME-Version: 1.0 To: Ian Smith References: In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: freebsd-questions@freebsd.org Subject: Re: kern.hz="100" stops high-pitched whine X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 02 Jul 2007 12:11:42 -0000 Ian Smith wrote: > On Sun, 01 Jul 2007 13:12:28 +0200 cpghost wrote: > > > I'm using fan-less Soekris (266 MHz) and EPIA (500 MHz) > > boards with -STABLE. Those boards have been emitting a > > very high pitched annoying whine, similar to a dog > > whistle. Not everyone I asked could hear it, but I was, > > and it was driving me crazy for months. > > > > This whine stopped entirely the moment I put > > kern.hz="100" in /boot/loader.conf and rebooted. > > Quite relieving! > > Possibly a beat frequency between the 1kHz default slicing and some > faster oscillator on board? You could play around with kern.clockrate, > sometimes quite small frequency changes make a difference, especially if > it's a harmonic. Default HZ jumped from 100 to 1000 probably around the > time when more servers were seen running at nearer 3000MHz than 300 :) > Interesting! I've booted the EPIA with Hz=840 and Hz=1160, and the whine was *considerably* quieter in both cases. It really seemed to be some kind of harmonic oscillation at Hz=1000. Now I'm back to HZ=100, which seems to be ideal. > > Are there any reasons NOT changing kern.hz from the > > default 1000 back to 100? With my typical mix of > > desktop apps (EPIA) and networking / server (Soekris), > > everything seems to be running just as smoothly with > > 100 Hz than with 1000 Hz (testing now for two weeks > > without problems). Even playing videos with mplayer > > on the EPIA doesn't look different in any way. > > No problem then, and a lighter interrupt load; probably enough to notice > in top. If you want to run dummynet or something else? wanting quicker > ticking you could try HZ=200 - 500. 200Hz on my Celeron 300 works well. > > > Is it okay to stay with 100 Hz with this type of > > low-speed CPU/boards? Or are there some compelling > > reasons not to? > > If it's happy, smooth and keeping up, it's fine. > > Cheers, Ian > I'll stay with 100 Hz for now. Should I need dummynet, I'll crank it up slowly. Thanks, -cpghost. -- Cordula's Web. http://www.cordula.ws/