Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751072AbbD3OHe (ORCPT ); Thu, 30 Apr 2015 10:07:34 -0400 Received: from mail.phunq.net ([184.71.0.62]:53218 "EHLO starbase.phunq.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750768AbbD3OHa (ORCPT ); Thu, 30 Apr 2015 10:07:30 -0400 Message-ID: <55423732.2070509@phunq.net> Date: Thu, 30 Apr 2015 07:07:46 -0700 From: Daniel Phillips User-Agent: Mozilla/5.0 (X11; Linux i686; rv:31.0) Gecko/20100101 Thunderbird/31.6.0 MIME-Version: 1.0 To: Mike Galbraith CC: Dave Chinner , linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, tux3@tux3.org, "Theodore Ts'o" , OGAWA Hirofumi Subject: Re: xfs: does mkfs.xfs require fancy switches to get decent performance? (was Tux3 Report: How fast can we fsync?) References: <8f886f13-6550-4322-95be-93244ae61045@phunq.net> <1430274071.3363.4.camel@gmail.com> <1906f271-aa23-404b-9776-a4e2bce0c6aa@phunq.net> <1430289213.3693.3.camel@gmail.com> <1430325763.19371.41.camel@gmail.com> <1430334326.7360.25.camel@gmail.com> <20150430002008.GY15810@dastard> <1430395641.3180.94.camel@gmail.com> <1430401693.3180.131.camel@gmail.com> In-Reply-To: <1430401693.3180.131.camel@gmail.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2390 Lines: 53 On 04/30/2015 06:48 AM, Mike Galbraith wrote: > On Thu, 2015-04-30 at 05:58 -0700, Daniel Phillips wrote: >> On Thursday, April 30, 2015 5:07:21 AM PDT, Mike Galbraith wrote: >>> On Thu, 2015-04-30 at 04:14 -0700, Daniel Phillips wrote: >>> >>>> Lovely sounding argument, but it is wrong because Tux3 still beats XFS >>>> even with seek time factored out of the equation. >>> >>> Hm. Do you have big-storage comparison numbers to back that? I'm no >>> storage guy (waiting for holographic crystal arrays to obsolete all this >>> crap;), but Dave's big-storage guy words made sense to me. >> >> This has nothing to do with big storage. The proposition was that seek >> time is the reason for Tux3's fsync performance. That claim was easily >> falsified by removing the seek time. >> >> Dave's big storage words are there to draw attention away from the fact >> that XFS ran the Git tests four times slower than Tux3 and three times >> slower than Ext4. Whatever the big storage excuse is for that, the fact >> is, XFS obviously sucks at little storage. > > If you allocate spanning the disk from start of life, you're going to > eat seeks that others don't until later. That seemed rather obvious and > straight forward. It is a logical falacy. It mixes a grain of truth (spreading all over the disk causes extra seeks) with an obvious falsehood (it is not necessarily the only possible way to avoid long term fragmentation). > He flat stated that xfs has passable performance on > single bit of rust, and openly explained why. I see no misdirection, > only some evidence of bad blood between you two. Raising the spectre of theoretical fragmentation issues when we have not even begun that work is a straw man and intellectually dishonest. You have to wonder why he does it. It is destructive to our community image and harmful to progress. > No, I won't be switching to xfs any time soon, but then it would take a > hell of a lot of evidence to get me to move away from ext4. I trust > ext[n] deeply because it has proven many times over the years that it > can take one hell of a lot (of self inflicted wounds;). Regards, Daniel -- 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/