From owner-freebsd-questions@FreeBSD.ORG Mon Jul 2 16:51:32 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 4525616A503 for ; Mon, 2 Jul 2007 16:51:32 +0000 (UTC) (envelope-from cswiger@mac.com) Received: from pi.codefab.com (pi.codefab.com [199.103.21.227]) by mx1.freebsd.org (Postfix) with ESMTP id 1786013C4C6 for ; Mon, 2 Jul 2007 16:51:32 +0000 (UTC) (envelope-from cswiger@mac.com) Received: from localhost (localhost [127.0.0.1]) by pi.codefab.com (Postfix) with ESMTP id A490A5FB0; Mon, 2 Jul 2007 12:51:31 -0400 (EDT) X-Virus-Scanned: amavisd-new at codefab.com Received: from pi.codefab.com ([127.0.0.1]) by localhost (pi.codefab.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id Je+tR6vpEmeI; Mon, 2 Jul 2007 12:51:27 -0400 (EDT) Received: from [192.168.1.130] (pool-96-224-41-41.nycmny.east.verizon.net [96.224.41.41]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by pi.codefab.com (Postfix) with ESMTP id 6C58F5D24; Mon, 2 Jul 2007 12:51:27 -0400 (EDT) Message-ID: <46892D0B.3030205@mac.com> Date: Mon, 02 Jul 2007 12:51:23 -0400 From: Chuck Swiger User-Agent: Thunderbird 1.5.0.12 (Windows/20070509) MIME-Version: 1.0 To: Jack Stone 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 16:51:32 -0000 Jack Stone wrote: [ ... ] > A while ago, I noticed someone's kernel config that included: > hertz=2000 which made me wonder where this setting info comes from? > > I've been using hertz=1000 however, with my much faster boxes, is this > appropriate now? It depends on what you are doing: it is most useful to tune HZ higher when machines are being used as firewalls/routers and/or are using device polling. Faster HZ rates cause greater system overhead but will give shorter latency, up to a limiting point. In simpler words, tuning HZ too high is bad. :-) One needs to do measurements and tune appropriately. -- -Chuck