From mboxrd@z Thu Jan 1 00:00:00 1970 From: Bill Davidsen Subject: Re: MDP major registration Date: Wed, 26 Mar 2008 11:54:39 -0400 Message-ID: <47EA71BF.8050800@tmr.com> References: <47D90614.9040206@free.fr> <18408.36753.223347.129420@notabene.brown> <47E92EE2.1080108@free.fr> <20080326065232.GA21970@percy.comedia.it> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20080326065232.GA21970@percy.comedia.it> Sender: linux-raid-owner@vger.kernel.org To: linux-raid@vger.kernel.org List-Id: linux-raid.ids Luca Berra wrote: > On Tue, Mar 25, 2008 at 05:57:06PM +0100, Hubert Verstraete wrote: >> Neil Brown wrote: >>> On Thursday March 13, hubskml@free.fr wrote: >>>> Neil, >>>> >>>> What is the status of the major for the partitionable arrays ? >>> >>> automatically determined at runtime. >>> >>>> I see that it is 254, which is in the experimental section, >>>> according to the official Linux device list >>>> (http://www.lanana.org/docs/device-list/). >>>> Will there be an official registration ? >>> >>> No. Is there any need? >> >> I got this question in mind when I saw that mkfs.xfs source code was >> referring to the MD major to tune its parameters on an MD device, >> while it ignores MDP devices. >> If there were reasons to register MD, wouldn't they apply to MDP too ? > > i don't think so: > bluca@percy ~ $ grep mdp /proc/devices > 253 mdp Why is it important to have XFS tune its parameters for md and not for mdp? I don't understand your conclusion here, is tuning not needed for mdp, or so meaningless that it doesn't matter, or that XFS code reads /proc/devices, or ??? I note that device-mapper also has a dynamic major, what does XFS make of that? I don't know how much difference tuning makes, but if it's worth doing at all, it should be done for mdp as well, I would think. -- Bill Davidsen "Woe unto the statesman who makes war without a reason that will still be valid when the war is over..." Otto von Bismark