From owner-freebsd-performance@FreeBSD.ORG Mon May 2 12:48:36 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 2E42516A4CF; Mon, 2 May 2005 12:48:36 +0000 (GMT) Received: from ms1.as.pvp.se (dns.pvp.se [213.64.187.226]) by mx1.FreeBSD.org (Postfix) with ESMTP id 7C54443D41; Mon, 2 May 2005 12:48:35 +0000 (GMT) (envelope-from kama@pvp.se) Received: by ms1.as.pvp.se (Postfix, from userid 1001) id 5701EA7; Mon, 2 May 2005 14:48:33 +0200 (CEST) Received: from localhost (localhost [127.0.0.1]) by ms1.as.pvp.se (Postfix) with ESMTP id 52C16A6; Mon, 2 May 2005 14:48:33 +0200 (CEST) Date: Mon, 2 May 2005 14:48:33 +0200 (CEST) From: kama X-X-Sender: kama@ns1.as.pvp.se To: Eric Anderson In-Reply-To: <42761FA7.1030500@centtech.com> Message-ID: <20050502144658.H22614@ns1.as.pvp.se> References: <20050501112351.4184.qmail@web41205.mail.yahoo.com> <42761FA7.1030500@centtech.com> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII cc: freebsd-performance@freebsd.org cc: Robert Watson cc: =?ISO-8859-15?Q?=22Arne_=5C=22W=F6rner=5C=22=22?= 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: Mon, 02 May 2005 12:48:36 -0000 On Mon, 2 May 2005, Eric Anderson wrote: > I'll be honest here, I don't care much if the speed difference between > 4.X and 5.X is measureable, or whatever. What I find is a little > telling of an issue somewhere, is that READS are slower than WRITES! > This is totally bogus to me - dd'ing a file to a filesystem, then > umounting should take longer than dd'ing from the disk to /dev/null, it > nearly every config I can dream up. Maybe it's the speed at which > /dev/null can gobble bits (seems highly unlikely!), or maybe GEOM is > busy doing a check or some routine to data being accessed directly from > the disk device instead of through a filesystem? I don't know, but it > is an issue, and I'm sure we'll get nailed up to a fence in some > benchmark somewhere if we don't fix it.. dev-null is not the issue... my own written testprogram that only read up data to a buffer in memory showed the same results as doing a dd to dev-null. /Bjorn