From owner-freebsd-current@FreeBSD.ORG Mon Sep 27 03:15:33 2004 Return-Path: Delivered-To: freebsd-current@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 5A31E16A4CE for ; Mon, 27 Sep 2004 03:15:33 +0000 (GMT) Received: from mail2.speakeasy.net (mail2.speakeasy.net [216.254.0.202]) by mx1.FreeBSD.org (Postfix) with ESMTP id 2C3CE43D2F for ; Mon, 27 Sep 2004 03:15:33 +0000 (GMT) (envelope-from jmg@hydrogen.funkthat.com) Received: (qmail 5274 invoked from network); 27 Sep 2004 03:15:32 -0000 Received: from gate.funkthat.com (HELO hydrogen.funkthat.com) ([69.17.45.168]) (envelope-sender ) by mail2.speakeasy.net (qmail-ldap-1.03) with SMTP for ; 27 Sep 2004 03:15:32 -0000 Received: from hydrogen.funkthat.com (xqvcpa@localhost.funkthat.com [127.0.0.1])i8R3FVlb032609; Sun, 26 Sep 2004 20:15:32 -0700 (PDT) (envelope-from jmg@hydrogen.funkthat.com) Received: (from jmg@localhost) by hydrogen.funkthat.com (8.12.10/8.12.10/Submit) id i8R3FTSA032608; Sun, 26 Sep 2004 20:15:29 -0700 (PDT) Date: Sun, 26 Sep 2004 20:15:29 -0700 From: John-Mark Gurney To: Mauro Triulzi Message-ID: <20040927031529.GA22681@funkthat.com> Mail-Followup-To: Mauro Triulzi , =?iso-8859-1?Q?S=F8ren?= Schmidt , freebsd-current@freebsd.org, Jeremy Chadwick References: <20040926044943.I40616-100000@mxb.saturn-tech.com> <200409261332.23227.michaelnottebrock@gmx.net> <4156B234.1090603@DeepCore.dk> <41575CCB.40107@freesurf.ch> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <41575CCB.40107@freesurf.ch> User-Agent: Mutt/1.4.1i X-Operating-System: FreeBSD 4.2-RELEASE i386 X-PGP-Fingerprint: B7 EC EF F8 AE ED A7 31 96 7A 22 B3 D8 56 36 F4 X-Files: The truth is out there X-URL: http://resnet.uoregon.edu/~gurney_j/ X-Resume: http://resnet.uoregon.edu/~gurney_j/resume.html cc: freebsd-current@freebsd.org cc: Jeremy Chadwick cc: =?iso-8859-1?Q?S=F8ren?= Schmidt Subject: Re: ATA disk performance (ICH2 controller), some testsandcomparison with Linux 2.6.5 X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list Reply-To: John-Mark Gurney List-Id: Discussions about the use of FreeBSD-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 27 Sep 2004 03:15:33 -0000 Mauro Triulzi wrote this message on Mon, Sep 27, 2004 at 02:20 +0200: > ii) Now I tried a fair raw throughput comparison between Linux and > FreeBSD. This time I read always the same whole (Linux) partition > (~4GB) so that the results should be comparable. I always used native > dd (FreeBSD and Linux). A measure with Linux dd under emulation > in FreeBSD gave yet the same result: > > dd if=/dev/ad0s9 bs=nnn of=/dev/null > FreeBSD: > nnn=4k: 4301789184 bytes transferred in 170.031898 secs (25299895 > bytes/sec) > nnn=8k: 4301789184 bytes transferred in 114.446100 secs (37587905 > bytes/sec) > nnn=16k: 4301789184 bytes transferred in 87.794076 secs (48998627 > bytes/sec) > nnn=64k: 4301789184 bytes transferred in 89.515195 secs (48056525 > bytes/sec) > nnn=512k: 4301789184 bytes transferred in 90.357666 secs (47608458 > bytes/sec) > (no significant changes before or after reinit) > > Linux: > nnn=4k: 4301789184 bytes transferred in 93 secs (~46 Mbytes/sec) > nnn=8k: 4301789184 bytes transferred in 86 secs (~50 Mbytes/sec) > nnn=16k: 4301789184 bytes transferred in 90 secs (~48 Mbytes/sec) > nnn=64k: 4301789184 bytes transferred in 95 secs (~45 Mbytes/sec) > nnn=512k: 4301789184 bytes transferred in 92 secs (~47 Mbytes/sec) > > I notice, that the rates are very similar if bs >= 16k. Under FreeBSD > the raw throughput rate depends on the block size. Read rate under Linux > is independent of the block size. Is there a special reason for that? Last I heard Linux did not have a raw device.. this means that it will always be cached, and will do various read-ahead optimizations, while FreeBSD does not have a buffered/cooked device anymore.. w/o the cooked device FreeBSD has to suffer the latency of the command to the drive... -- John-Mark Gurney Voice: +1 415 225 5579 "All that I will do, has been done, All that I have, has not."