Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1762233AbYBSCpr (ORCPT ); Mon, 18 Feb 2008 21:45:47 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754977AbYBSCpj (ORCPT ); Mon, 18 Feb 2008 21:45:39 -0500 Received: from mx1.redhat.com ([66.187.233.31]:45549 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752362AbYBSCpi (ORCPT ); Mon, 18 Feb 2008 21:45:38 -0500 Date: Tue, 19 Feb 2008 02:45:33 +0000 From: Alasdair G Kergon To: Ric Wheeler Cc: Michael Tokarev , device-mapper development , Andi Kleen , linux-kernel@vger.kernel.org Subject: Re: [dm-devel] Re: [PATCH] Implement barrier support for single device DM devices Message-ID: <20080219024533.GC4066@agk.fab.redhat.com> Mail-Followup-To: Ric Wheeler , Michael Tokarev , device-mapper development , Andi Kleen , linux-kernel@vger.kernel.org References: <20080215120821.GA8267@basil.nowhere.org> <20080215122002.GM29914@agk.fab.redhat.com> <47B58EAA.8040405@msgid.tls.msk.ru> <20080215142010.GA29552@one.firstfloor.org> <20080215141229.GB1788@agk.fab.redhat.com> <47B97E87.6040209@emc.com> <47B9870B.8060005@msgid.tls.msk.ru> <47B98D8A.7090506@emc.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <47B98D8A.7090506@emc.com> User-Agent: Mutt/1.4.1i Organization: Red Hat UK Ltd. Registered in England and Wales, number 03798903. Registered Office: Amberley Place, 107-111 Peascod Street, Windsor, Berkshire, SL4 1TE. Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 860 Lines: 22 On Mon, Feb 18, 2008 at 08:52:10AM -0500, Ric Wheeler wrote: > I understand that. Most of the time, dm or md devices are composed of > uniform components which will uniformly support (or not) the cache flush > commands used by barriers. As a dm developer, it's "almost none of the time" because trivial configurations aren't the ones that require lots of testing effort. Let's stop arguing over "most of the time":-) As Andi points out, there are certainly enough real-world users of "single linear or crypt target using one physical device" for it to be worth our supporting it. Alasdair -- agk@redhat.com -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/