From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965512AbbEMPtD (ORCPT ); Wed, 13 May 2015 11:49:03 -0400 Received: from mx1.redhat.com ([209.132.183.28]:47489 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S965109AbbEMPs6 (ORCPT ); Wed, 13 May 2015 11:48:58 -0400 From: Jeff Moyer To: Jens Axboe Cc: Shaohua Li , Subject: Re: [PATCH] blk: don't account discard request size References: <10cba6675b3e93f28b9c1c7a21e4b93b923e9531.1431467011.git.shli@fb.com> <55535D9C.3050706@fb.com> <55536C46.4020304@fb.com> X-PGP-KeyID: 1F78E1B4 X-PGP-CertKey: F6FE 280D 8293 F72C 65FD 5A58 1FF8 A7CA 1F78 E1B4 X-PCLoadLetter: What the f**k does that mean? Date: Wed, 13 May 2015 11:48:56 -0400 In-Reply-To: <55536C46.4020304@fb.com> (Jens Axboe's message of "Wed, 13 May 2015 11:22:46 -0400") Message-ID: User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/24.3 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Jens Axboe writes: > On 05/13/2015 11:00 AM, Jeff Moyer wrote: >> Jens Axboe writes: >> >>> That would be better. But I'm still not sure we want to turn off >>> accounting for discards. For the mixed write/discard cases it's >>> definitely confusing. The better option would be to account it as a >>> discard and not a write. Preferably in a way that would not break >>> existing tools, but so that they could get updated to support it. >> >> Are you suggesting adding a few fields to the end of diskstats or adding >> a new proc file altogether? (or something else?) > > I didn't suggest any specific solution. Obviously it'd be nice if we > could just extend diskstats, but that might break userland. Worth > checking up on. OK, I didn't know if you had any other tricks up your sleeve. We've had luck adding fields to the end of some files in the past (I'd really have to dig to remember what files), but I'm fairly certain this would break *something*. It's definitely safer (albeit uglier) to just add a file. -Jeff