From owner-freebsd-performance@FreeBSD.ORG Sun May 1 11:23:51 2005 Return-Path: Delivered-To: freebsd-performance@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 9D0EE16A4CE for ; Sun, 1 May 2005 11:23:51 +0000 (GMT) Received: from web41205.mail.yahoo.com (web41205.mail.yahoo.com [66.218.93.38]) by mx1.FreeBSD.org (Postfix) with SMTP id 52B4343D45 for ; Sun, 1 May 2005 11:23:51 +0000 (GMT) (envelope-from arne_woerner@yahoo.com) Received: (qmail 4186 invoked by uid 60001); 1 May 2005 11:23:51 -0000 Comment: DomainKeys? See http://antispam.yahoo.com/domainkeys DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=s1024; d=yahoo.com; b=nYxPKv9wHaWywpjdlEszERk9jqhrnHt9L7C95xzKnKZq3jPpyTDxh3yyksG1iDD111xEtqQiNe3BYYHYMErbBIrpUC2icKypykN50bx2FMx+bM7kySTDok4pE9Vx24uq9nCcTuE6zcErXqLAfi6e0c9n7q+6kFcFC0TJUBRps3g= ; Message-ID: <20050501112351.4184.qmail@web41205.mail.yahoo.com> Received: from [83.129.191.33] by web41205.mail.yahoo.com via HTTP; Sun, 01 May 2005 04:23:51 PDT Date: Sun, 1 May 2005 04:23:51 -0700 (PDT) From: Arne "Wörner" To: Robert Watson In-Reply-To: 6667 MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii cc: freebsd-performance@freebsd.org Subject: Re: Very low disk performance on 5.x X-BeenThere: freebsd-performance@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: Performance/tuning List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 01 May 2005 11:23:51 -0000 --- Robert Watson wrote: > On Sat, 30 Apr 2005, Arne WXrner wrote: > > 3. The man page geom(4) of R5.3 says "The GEOM framework > > provides an infrastructure in which "classes" can per- > > form transformations on disk I/O requests on their path > > from the upper kernel to the device drivers and back. > > > > Could it be, that geom slows something down (in some boxes the > > reading > > ops are very slow; in my box the writing ops are very slow)? > > [...] > against a further offset region of ad0. If they're against the > same bits of disk, the main difference here will be the > additional processing of the layers in the stack. A little > bit of math is required to figure out the offset, but dd > should be usable to figure out the incremental cost. > I used the following commands: 1. dd if=/dev/ad0s2a bs=16k count=10000 of=/dev/null 2. dd if=/dev/ad0 iseek=2100357 bs=16k count=10000 of=/dev/null (I think I did the math correctly; indeed the read speed of my ad0 varies between 45MB/sec (iseek=0) and 25MB/sec (in the end) with bs=128k). The results were nearly the same (both between 26MB/sec and 28MB/sec). Maybe I should have done it in single user mode. My other hard disc ad1 (it is newer and bigger and faster and more furious) behaves better (but I can just try writing via the file system (ufs+s) and a final sync): The sync just needs .24sec of 18.28 seconds; the read and write speed is nearly the same (about 37MB/sec+/-1MB/sec). Is there anything else, that could help to find the reason for the difference between ad0's speed in R4.11 and R5.3? -Arne __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com