From owner-freebsd-stable@FreeBSD.ORG Thu Oct 4 12:34:03 2007 Return-Path: Delivered-To: freebsd-stable@FreeBSD.ORG Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 1D53916A418 for ; Thu, 4 Oct 2007 12:34:03 +0000 (UTC) (envelope-from olli@lurza.secnetix.de) Received: from lurza.secnetix.de (lurza.secnetix.de [83.120.8.8]) by mx1.freebsd.org (Postfix) with ESMTP id 8D00313C46E for ; Thu, 4 Oct 2007 12:34:02 +0000 (UTC) (envelope-from olli@lurza.secnetix.de) Received: from lurza.secnetix.de (localhost [127.0.0.1]) by lurza.secnetix.de (8.14.1/8.14.1) with ESMTP id l94CWddY056144; Thu, 4 Oct 2007 14:32:45 +0200 (CEST) (envelope-from oliver.fromme@secnetix.de) Received: (from olli@localhost) by lurza.secnetix.de (8.14.1/8.14.1/Submit) id l94CWd6W056143; Thu, 4 Oct 2007 14:32:39 +0200 (CEST) (envelope-from olli) Date: Thu, 4 Oct 2007 14:32:39 +0200 (CEST) Message-Id: <200710041232.l94CWd6W056143@lurza.secnetix.de> From: Oliver Fromme To: freebsd-stable@FreeBSD.ORG, matrix@itlegion.ru In-Reply-To: <02d401c805cb$abf59ec0$0c00a8c0@Artem> X-Newsgroups: list.freebsd-stable User-Agent: tin/1.8.3-20070201 ("Scotasay") (UNIX) (FreeBSD/6.2-STABLE-20070808 (i386)) MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 8bit X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-2.1.2 (lurza.secnetix.de [127.0.0.1]); Thu, 04 Oct 2007 14:32:45 +0200 (CEST) Cc: Subject: Re: Quation about HZ kernel option X-BeenThere: freebsd-stable@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list Reply-To: freebsd-stable@FreeBSD.ORG, matrix@itlegion.ru List-Id: Production branch of FreeBSD source code List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 04 Oct 2007 12:34:03 -0000 Artem Kuchin <> wrote: > What value of HZ option would you recommend > for a hosting (web) server with a lot of processes > (about 900) and polling off (as decided from previous > discussion polling is useless in > this situation). In that case, I would recommend not to override the default at all (which is 1000). > What parts of kernel does this option affect? What > depends on it? The value of HZ specifies the minimum timing quantum of the kernel. It affects the granularity of the scheduler and all timing-related functions (nanosleep(2) and others), and the accuracy of dummynet and polling. I'm sure there are more things. Basically, the kernel cannot handle time slices smaller than 1/HZ seconds, for any purpose. Best regards Oliver -- Oliver Fromme, secnetix GmbH & Co. KG, Marktplatz 29, 85567 Grafing b. M. Handelsregister: Registergericht Muenchen, HRA 74606, Geschäftsfuehrung: secnetix Verwaltungsgesellsch. mbH, Handelsregister: Registergericht Mün- chen, HRB 125758, Geschäftsführer: Maik Bachmann, Olaf Erb, Ralf Gebhart FreeBSD-Dienstleistungen, -Produkte und mehr: http://www.secnetix.de/bsd One Unix to rule them all, One Resolver to find them, One IP to bring them all and in the zone to bind them.