From owner-freebsd-stable@FreeBSD.ORG Wed Jun 22 09:36:30 2005 Return-Path: X-Original-To: freebsd-stable@FreeBSD.ORG 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 F24F516A41C for ; Wed, 22 Jun 2005 09:36:30 +0000 (GMT) (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 52C0C43D1D for ; Wed, 22 Jun 2005 09:36:30 +0000 (GMT) (envelope-from olli@lurza.secnetix.de) Received: from lurza.secnetix.de (sbapqb@localhost [127.0.0.1]) by lurza.secnetix.de (8.13.1/8.13.1) with ESMTP id j5M9aSqQ059386; Wed, 22 Jun 2005 11:36:28 +0200 (CEST) (envelope-from oliver.fromme@secnetix.de) Received: (from olli@localhost) by lurza.secnetix.de (8.13.1/8.13.1/Submit) id j5M9aR2a059385; Wed, 22 Jun 2005 11:36:27 +0200 (CEST) (envelope-from olli) Date: Wed, 22 Jun 2005 11:36:27 +0200 (CEST) Message-Id: <200506220936.j5M9aR2a059385@lurza.secnetix.de> From: Oliver Fromme To: freebsd-stable@FreeBSD.ORG, Michael Schuh In-Reply-To: <1dbad31505062108011b812ba8@mail.gmail.com> X-Newsgroups: list.freebsd-stable User-Agent: tin/1.5.4-20000523 ("1959") (UNIX) (FreeBSD/4.11-RELEASE (i386)) MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 8bit Cc: Subject: Re: FreeBSD MySQL still WAY slower than Linux X-BeenThere: freebsd-stable@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list Reply-To: freebsd-stable@FreeBSD.ORG, Michael Schuh List-Id: Production branch of FreeBSD source code List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 22 Jun 2005 09:36:31 -0000 Michael Schuh wrote: > now i have another question, if i use the same Os in 2 versions > (RELENG_4, RELENG_5) can i hope that the tests are made on the same > part of disk? Hope you always can. But rely on it you should not. ;-) > or in other words can an dd on the two OS' es so much different > because they use an > totally other part of disk? I think no, the strategie from dd under > one OS should not be changed if the OS-Version has changed. It's not the dd which decides where to put the file, it's the filesystem code. And yes, there can be differences between RELENG_4 and RELENG_5. In particular, in RELENG_5 you have UFS2, not the old UFS. There have always been changes to the FS code, for example I remember that the allocation of directories has changed some time ago to improve metadata performance for large trees (known as "dirpref"). As I said: The only way to make sure you hit the same physical place on the disk is to use a raw partition, not a file on some filesystem. Note that even small differences in the placement of the file can have a noticeable effect on the speed. Apart from the speed differences of the disk cylinders, it can also happen that the file is allocated in a non-contiguous way, especially if it is large and the filesystem already contains a lot of files, and/or had a lot of write+delete operations previously (i.e. causing fragmentation). > the part with serial IO related to database-performance have i > understand, but i quests me have the others understand > my meanings? That I don't know. Best regards Oliver -- Oliver Fromme, secnetix GmbH & Co KG, Oettingenstr. 2, 80538 München Any opinions expressed in this message may be personal to the author and may not necessarily reflect the opinions of secnetix in any way. "anyone new to programming should be kept as far from C++ as possible; actually showing the stuff should be considered a criminal offence" -- Jacek Generowicz