From owner-freebsd-questions@FreeBSD.ORG Sun Jul 1 14:16:19 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 2391216A400 for ; Sun, 1 Jul 2007 14:16:19 +0000 (UTC) (envelope-from smithi@nimnet.asn.au) Received: from gaia.nimnet.asn.au (nimbin.lnk.telstra.net [139.130.45.143]) by mx1.freebsd.org (Postfix) with ESMTP id 9825213C45D for ; Sun, 1 Jul 2007 14:16:17 +0000 (UTC) (envelope-from smithi@nimnet.asn.au) Received: from localhost (smithi@localhost) by gaia.nimnet.asn.au (8.8.8/8.8.8R1.5) with SMTP id AAA28826; Mon, 2 Jul 2007 00:16:05 +1000 (EST) (envelope-from smithi@nimnet.asn.au) Date: Mon, 2 Jul 2007 00:16:04 +1000 (EST) From: Ian Smith To: cpghost In-Reply-To: <20070701120022.DCC6C16A4A5@hub.freebsd.org> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII 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: Sun, 01 Jul 2007 14:16:19 -0000 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 :) > 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