From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mx1.redhat.com (mx1.redhat.com [172.16.48.31]) by int-mx1.corp.redhat.com (8.11.6/8.11.6) with ESMTP id i5L9u5000464 for ; Mon, 21 Jun 2004 05:56:05 -0400 Received: from mail.ukfsn.org (s2.ukfsn.org [217.158.120.143]) by mx1.redhat.com (8.12.10/8.12.10) with ESMTP id i5L9u3e1021500 for ; Mon, 21 Jun 2004 05:56:03 -0400 Received: from localhost (lucy.ukfsn.org [127.0.0.1]) by mail.ukfsn.org (Postfix) with ESMTP id 74B54E6D3E for ; Mon, 21 Jun 2004 10:55:15 +0100 (BST) Received: from mail.ukfsn.org ([127.0.0.1]) by localhost (lucy.ukfsn.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id 21878-19 for ; Mon, 21 Jun 2004 10:55:15 +0100 (BST) Received: from oak.dgreaves.com (modem-2777.putangitangi.dialup.pol.co.uk [81.78.202.217]) by mail.ukfsn.org (Postfix) with ESMTP id C5214E6A97 for ; Mon, 21 Jun 2004 10:55:14 +0100 (BST) Received: from ash.dgreaves.com ([10.0.0.66]) by oak.dgreaves.com with esmtp (Exim 4.20) id 1BcLYx-0001HL-EJ for linux-lvm@redhat.com; Mon, 21 Jun 2004 10:58:03 +0100 Message-ID: <40D6B0AA.4030700@dgreaves.com> Date: Mon, 21 Jun 2004 10:55:54 +0100 From: David Greaves MIME-Version: 1.0 Subject: Re: [linux-lvm] LVM2 seems to chop performance by 33% References: <40C86F52.4090500@dgreaves.com> <200406101105.47606.StuartHarper@tampabay.rr.com> <40C87F8A.7080304@dgreaves.com> <1086885029.13087.15.camel@localhost> <40D5D4D6.9020307@dgreaves.com> <20040620195316.GT6302@agk.surrey.redhat.com> In-Reply-To: <20040620195316.GT6302@agk.surrey.redhat.com> Content-Transfer-Encoding: 7bit Reply-To: LVM general discussion and development List-Id: LVM general discussion and development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , List-Id: Content-Type: text/plain; charset="us-ascii"; format="flowed" To: LVM general discussion and development Alasdair G Kergon wrote: >On Sun, Jun 20, 2004 at 07:17:58PM +0100, David Greaves wrote: > > >>No-one ever replied as to why blockdev --setra / --getra is not the same >>as that displayed in lvdisplay >>And it's not documented that I can find. There's a comment: "Not used by >>device-mapper." And that means.....? >> >> > >Any LVM read ahead setting is ignored by LVM2 i.e. not passed to the kernel. > >If it's demonstrated to be useful it could still be implemented, but >the current development priorities are still correctness and new features >rather than performance. > >Alasdair > > Thanks Alasdair It would be good to modify the docs to be clearer and maybe say "use blockdev --setra" David