From owner-freebsd-stable@FreeBSD.ORG Tue Feb 17 20:46:29 2009 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 447CC106564A; Tue, 17 Feb 2009 20:46:29 +0000 (UTC) (envelope-from scottl@samsco.org) Received: from pooker.samsco.org (pooker.samsco.org [168.103.85.57]) by mx1.freebsd.org (Postfix) with ESMTP id E83FF8FC1E; Tue, 17 Feb 2009 20:46:28 +0000 (UTC) (envelope-from scottl@samsco.org) Received: from phobos.local ([192.168.254.200]) (authenticated bits=0) by pooker.samsco.org (8.14.2/8.14.2) with ESMTP id n1HKkKkV097118; Tue, 17 Feb 2009 13:46:20 -0700 (MST) (envelope-from scottl@samsco.org) Message-ID: <499B221C.2050804@samsco.org> Date: Tue, 17 Feb 2009 13:46:20 -0700 From: Scott Long User-Agent: Mozilla/5.0 (Macintosh; U; Intel Mac OS X; en-US; rv:1.8.1.13) Gecko/20080313 SeaMonkey/1.1.9 MIME-Version: 1.0 To: Bruce Evans References: <499981AF.9030204@samsco.org> <20090217164203.4c586f48@ernst.jennejohn.org> <20090218073542.E5200@delplex.bde.org> In-Reply-To: <20090218073542.E5200@delplex.bde.org> X-Enigmail-Version: 0.95.6 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-Spam-Status: No, score=-4.4 required=3.8 tests=ALL_TRUSTED,BAYES_00 autolearn=ham version=3.1.8 X-Spam-Checker-Version: SpamAssassin 3.1.8 (2007-02-13) on pooker.samsco.org Cc: FreeBSD@FreeBSD.org, FreeBSD Current , Stable , Gary Jennejohn , scsi@FreeBSD.org Subject: Re: HEADS UP: More CAM fixes. X-BeenThere: freebsd-stable@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Production branch of FreeBSD source code List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 17 Feb 2009 20:46:30 -0000 Bruce Evans wrote: > On Tue, 17 Feb 2009, Gary Jennejohn wrote: > >> I tested this with an Adaptec 29160. I saw no real improvement in >> performance, but also no regressions. >> >> I suspect that the old disk I had attached just didn't have enough >> performance reserves to show an improvement. >> >> My test scenario was buildworld. Since /usr/src and /usr/obj were both >> on the one disk it got a pretty good workout. > ^^^^ low >> >> AMD64 X2 (2.5 GHz) with 4GB of RAM. > > Buildworld hardly uses the disk at all. It reads and writes a few hundred > MB. Ideally the i/o should go at disk speeds of 50-200MB/S and thus take > between 20 and 5 seconds. In practice, it will take a few more seconds. > physically but perhaps even less virtually due to parallelism. > > Bruce Yes, on modern machines, buildworld is bound almost completely by disk latency, and not at all by disk or controller bandwidth. Scott