From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933456AbaEMNl5 (ORCPT ); Tue, 13 May 2014 09:41:57 -0400 Received: from top.free-electrons.com ([176.31.233.9]:39049 "EHLO mail.free-electrons.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1752947AbaEMNlz (ORCPT ); Tue, 13 May 2014 09:41:55 -0400 Date: Tue, 13 May 2014 10:41:10 -0300 From: Ezequiel Garcia To: Greg Kroah-Hartman Cc: Brian Norris , "Gupta, Pekon" , David Woodhouse , "linux-mtd@lists.infradead.org" , Linux Kernel Subject: Re: [PATCH 1/4] mtd: Add sysfs attr to expose ECC stats Message-ID: <20140513134109.GA1504@arch.cereza> References: <1395403064-28113-1-git-send-email-ezequiel.garcia@free-electrons.com> <1395403064-28113-2-git-send-email-ezequiel.garcia@free-electrons.com> <20980858CB6D3A4BAE95CA194937D5E73EAB91D7@DBDE04.ent.ti.com> <20140401111359.GA3324@arch.cereza> <20980858CB6D3A4BAE95CA194937D5E73EAC31AE@DBDE04.ent.ti.com> <20140513005053.GZ28907@ld-irv-0074> <20140513022614.GA1447@arch.cereza> <20140513111524.GA29552@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20140513111524.GA29552@kroah.com> User-Agent: Mutt/1.5.22 (2013-10-16) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 13 May 01:15 PM, Greg Kroah-Hartman wrote: > On Mon, May 12, 2014 at 11:26:14PM -0300, Ezequiel Garcia wrote: > > On 12 May 05:50 PM, Brian Norris wrote: > > > > There are some guidelines about attributes in 'Documentation/filesystems/sysfs.txt' > > > > Though it's acceptable to put array of values of the "same type" in single sysfs file, > > > > But I'm still not confident on having all members of 'struct ecc_stats' being > > > > represented by single sysfs file > > > [...] > > > > > > I agree, it looks like the sysfs policy would recommend against putting > > > distinct properties in the same file. > > > > > > > OK... > > > > > I'm not sure if /sys/block//stat is a good example, as it does > > > violate this policy. It also seems to have some historical baggage. > > > > > > But there is potentially one good reason for putting this distinct > > > information in a single file: if the information must be returned > > > atomically. For disk stats, it might be important to get a consistent > > > snapshot of the disk stats (or nearly so, with minimal locking > > > overhead), which might change significantly between file accesses if > > > we're doing half a dozen file queries instead. > > > > > > This same reason may not apply to these ECC stats, since none of these > > > ECC stats are likely to be changing concurrently. > > > > > > > Right. > > > > > So I personally might lean toward "one file per attribute" here. > > > > > > > Yup, no problem. Greg, if you can confirm this it'd be great. > > Yes, that is the rule for sysfs, please do not put multiple values in a > single sysfs file for a variety of good reasons. > Will do! > > > > >> I hope this will still keep it machine readable. > > > > >Well, this is not a debugfs entry, so I'm not sure we want to add such debug > > > > >information. Anyone can take a look at the code and see what ecc_stats mean. > > > > > > The code or (as suggested by Pekon) the documentation > > > (Documentation/ABI/). Either way -- with a single 'ecc_stats' table, or > > > with 4 separate files -- they need to be documented. > > > > > > > Sure, will document in next round. > > This documentation is required, thanks. > Sure, no problem. -- Ezequiel García, Free Electrons Embedded Linux, Kernel and Android Engineering http://free-electrons.com