From owner-freebsd-stable@FreeBSD.ORG Wed Feb 23 16:23:03 2005 Return-Path: Delivered-To: freebsd-stable@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 8FDEE16A4CE; Wed, 23 Feb 2005 16:23:03 +0000 (GMT) Received: from no-such-agency.net (eschelon.no-such-agency.net [216.93.183.141]) by mx1.FreeBSD.org (Postfix) with ESMTP id 20BC543D1F; Wed, 23 Feb 2005 16:23:03 +0000 (GMT) (envelope-from jpp@cloudview.com) Received: from eschelon.no-such-agency.net (localhost [127.0.0.1]) by guardian (Postfix) with SMTP id C6C0A171734; Wed, 23 Feb 2005 08:23:02 -0800 (PST) Received: from no-such-agency.net ([216.93.183.141]) by eschelon.no-such-agency.net ([216.93.183.141]) with SMTP (gateway) id A0FAAA9CE2E; Wed, 23 Feb 2005 08:23:02 -0800 Received: from [192.168.2.120] (blackhole.no-such-agency.net [64.142.103.196]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by no-such-agency.net (Postfix) with ESMTP id 5A0FC171734; Wed, 23 Feb 2005 08:23:02 -0800 (PST) Message-ID: <421CADE6.2050205@cloudview.com> Date: Wed, 23 Feb 2005 08:23:02 -0800 From: John Pettitt Organization: CloudView Photographic User-Agent: Mozilla Thunderbird 1.0 (Windows/20041206) X-Accept-Language: en-us, en MIME-Version: 1.0 To: cpghost@cordula.ws References: <20050222193858.1C18C5D07@ptavv.es.net> <20050222214821.GA66879@epia2.farid-hajji.net> In-Reply-To: <20050222214821.GA66879@epia2.farid-hajji.net> X-Enigmail-Version: 0.90.1.1 X-Enigmail-Supports: pgp-inline, pgp-mime Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit X-Content-Filtered-By: Mailman/MimeDel 2.1.1 cc: Emanuel Strobl cc: freebsd-stable@freebsd.org cc: Robert Watson Subject: Re: HZ=1000 on slow CPUs considered harmful? X-BeenThere: freebsd-stable@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: Production branch of FreeBSD source code List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 23 Feb 2005 16:23:03 -0000 cpghost@cordula.ws wrote: >On Tue, Feb 22, 2005 at 07:56:03PM +0000, Robert Watson wrote: > > >>In 6-CURRENT, HZ is 1000 for amd64, i386, and ia64, but 100 for other >>platforms (i.e., ppc, arm, and alpha). I'm not opposed to merging the HZ >>change to RELENG_5 at some point, but given that occasional nits, such as >>the TCP nit, are turning up, I think it's worth waiting until after 5.4. >> >> > >Wouldn't that be a problem for slow CPUs like VIA C3 (EPIA) or GEODE >(Soekris)? For fast CPUs, it's not that much overhead, but for slow >CPUs? > >Can HZ remain user-configurable? > > > HZ=1000 has causes a lot of problems for Linux boxes where the system no longer keeps accurate time because of lost clock interrupts under high load (video playback seem to be the favorite) - see the ntp lists for extensive discussion. Is this change really worth the hassle? John