From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-3.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 60A6FC433DF for ; Tue, 25 Aug 2020 22:31:18 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3F92B206EB for ; Tue, 25 Aug 2020 22:31:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726303AbgHYWbR (ORCPT ); Tue, 25 Aug 2020 18:31:17 -0400 Received: from mail109.syd.optusnet.com.au ([211.29.132.80]:34438 "EHLO mail109.syd.optusnet.com.au" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726466AbgHYWbR (ORCPT ); Tue, 25 Aug 2020 18:31:17 -0400 Received: from dread.disaster.area (pa49-181-146-199.pa.nsw.optusnet.com.au [49.181.146.199]) by mail109.syd.optusnet.com.au (Postfix) with ESMTPS id 98DBDD7D4A7; Wed, 26 Aug 2020 08:31:11 +1000 (AEST) Received: from dave by dread.disaster.area with local (Exim 4.92.3) (envelope-from ) id 1kAhTC-0000VW-Dy; Wed, 26 Aug 2020 08:31:10 +1000 Date: Wed, 26 Aug 2020 08:31:10 +1000 From: Dave Chinner To: "Darrick J. Wong" Cc: Eric Sandeen , Anthony Iliopoulos , linux-xfs@vger.kernel.org Subject: Re: [PATCH 0/6] xfsprogs: blockdev dax detection and warnings Message-ID: <20200825223110.GQ12131@dread.disaster.area> References: <20200824203724.13477-1-ailiop@suse.com> <20200824225533.GA12131@dread.disaster.area> <4aa834dd-5220-6312-e28f-1a94a56b1cc0@sandeen.net> <20200825144015.GB6096@magnolia> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200825144015.GB6096@magnolia> X-Optus-CM-Score: 0 X-Optus-CM-Analysis: v=2.3 cv=QKgWuTDL c=1 sm=1 tr=0 cx=a_idp_d a=GorAHYkI+xOargNMzM6qxQ==:117 a=GorAHYkI+xOargNMzM6qxQ==:17 a=kj9zAlcOel0A:10 a=y4yBn9ojGxQA:10 a=7-415B0cAAAA:8 a=tDArTbVnjOhj1pgSmKoA:9 a=iW2Ia2TNvcxNdp0J:21 a=GsDbAy2E_e3QRq6g:21 a=CjuIK1q_8ugA:10 a=biEYGPWJfzWAr4FL6Ov7:22 Sender: linux-xfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-xfs@vger.kernel.org On Tue, Aug 25, 2020 at 07:40:15AM -0700, Darrick J. Wong wrote: > Zooming out a bit, maybe we should instead introduce a new "tuning" > parameter for -d and -r so that administrators could tune the filesystem > for specific purposes: > > -d tune=dax: Reject if device not dax, set daxinherit=1, set > extsize/su/sw to match PMD > > -d tune=ssd: Set agcount to match the number of CPUs if > possible, make the log larger to support a large number of > threads and iops. > > -d tune=rotational: Probably does nothing. ;) > > -d tune=auto: Query blkid to guess which of the above three > profiles we should use. > > -d tune=none: No tuning. > > And then you'd do the same for the realtime device. Please, no. The problem with this is that a specific "tune" will need to vary over time (e.g. when reflink is supported with DAX) and so now we back to the same situation where the definition of "tune=dax" changes depending on what version of mkfs you use. Hence you can still make a filesystem that the kernel won't mount because you have a xfsprogs that supports DAX+reflink and a kernel that doesn't. I just don't see this as a viable way to produce filesystems that work for specific situations because it doesn't solve the kernel vs xfsprogs version support issue that requires tweaking mkfs parameters manually to avoid... > This would help us get rid of the seeeekret mkfs wrapper that we use to > make it easier for our internal customers to use DAX since mkfs.xfs > doesn't support config files. Let's fix that, then. I've written a bunch of stuff in the past couple of years that uses basic ini config files via a simple library and it just works. If people are happy with ini format config files via a library, then I'll just go do that, eh? Cheers, Dave. -- Dave Chinner david@fromorbit.com