From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from top.free-electrons.com ([176.31.233.9] helo=mail.free-electrons.com) by bombadil.infradead.org with esmtp (Exim 4.80.1 #2 (Red Hat Linux)) id 1Wk2Qv-0006pu-QM for linux-mtd@lists.infradead.org; Tue, 13 May 2014 02:27:10 +0000 Date: Mon, 12 May 2014 23:26:14 -0300 From: Ezequiel Garcia To: Brian Norris Subject: Re: [PATCH 1/4] mtd: Add sysfs attr to expose ECC stats Message-ID: <20140513022614.GA1447@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> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20140513005053.GZ28907@ld-irv-0074> Cc: "linux-mtd@lists.infradead.org" , David Woodhouse , "Gupta, Pekon" , Linux Kernel , Greg Kroah-Hartman List-Id: Linux MTD discussion mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , 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. > > >> 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. -- Ezequiel García, Free Electrons Embedded Linux, Kernel and Android Engineering http://free-electrons.com