From owner-freebsd-current@FreeBSD.ORG Sat May 22 00:46:50 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 5180E16A4CE for ; Sat, 22 May 2004 00:46:50 -0700 (PDT) Received: from critter.freebsd.dk (critter.freebsd.dk [212.242.86.163]) by mx1.FreeBSD.org (Postfix) with ESMTP id 8A12F43D2F for ; Sat, 22 May 2004 00:46:49 -0700 (PDT) (envelope-from phk@phk.freebsd.dk) Received: from critter.freebsd.dk (localhost [127.0.0.1]) by critter.freebsd.dk (8.12.11/8.12.11) with ESMTP id i4M7kB3R045923; Sat, 22 May 2004 09:46:11 +0200 (CEST) (envelope-from phk@phk.freebsd.dk) To: "Kevin Oberman" From: "Poul-Henning Kamp" In-Reply-To: Your message of "Fri, 21 May 2004 15:47:29 PDT." <20040521224729.680285D0A@ptavv.es.net> Date: Sat, 22 May 2004 09:46:11 +0200 Message-ID: <45922.1085211971@critter.freebsd.dk> cc: freebsd-current@freebsd.org Subject: Re: Disk performance under CURRENT X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: Discussions about the use of FreeBSD-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sat, 22 May 2004 07:46:50 -0000 In message <20040521224729.680285D0A@ptavv.es.net>, "Kevin Oberman" writes: >I just ran test of disk writing performance under V4 (STABLE) and V5 >(CURRENT) and was surprised at the difference. > >The test was simple and not at all rigorous. Just a dd bs=256k >if=/dev/zero of=/dev/ad2. This is about the simplest way of dealing with >a disk. No file system or anything else. Just raw data to the device. > >Under STABLE, I get an average of 25 MB/sec to the disk. Under CURRENT, >it drops to 15 MB/sec. I did this because I had noted that it was now >taking over an hour to backup my system disk (40 GB) when it was only >taking 40 minutes when I was running V4.6. The STABLE system was built >yesterday. The CURRENT system last Sunday. > >Any idea why this is so much slower? It looks to me like it must be in >either geom or the disk driver. GEOM is slower than 4-stable in a degenerate case like this, but it sounds to me like there is something else involved here too. Have you removed WITNESS from your kernel ? -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 phk@FreeBSD.ORG | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence.