Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758297AbcLSSVR (ORCPT ); Mon, 19 Dec 2016 13:21:17 -0500 Received: from mail-wj0-f169.google.com ([209.85.210.169]:33291 "EHLO mail-wj0-f169.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753453AbcLSSVP (ORCPT ); Mon, 19 Dec 2016 13:21:15 -0500 Content-Type: text/plain; charset=windows-1252 Mime-Version: 1.0 (Mac OS X Mail 9.3 \(3124\)) Subject: Re: [PATCHSET v4] blk-mq-scheduling framework From: Paolo Valente In-Reply-To: Date: Mon, 19 Dec 2016 19:21:10 +0100 Cc: Jens Axboe , linux-block@vger.kernel.org, Linux-Kernal , Omar Sandoval , Linus Walleij , Ulf Hansson , Mark Brown Message-Id: References: <1481933536-12844-1-git-send-email-axboe@fb.com> <7A8A5078-E9B8-4EBF-BAB1-9E8EEBF3A043@linaro.org> To: Jens Axboe X-Mailer: Apple Mail (2.3124) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: 8bit X-MIME-Autoconverted: from quoted-printable to 8bit by mail.home.local id uBJILMcX032706 Content-Length: 2849 Lines: 68 > Il giorno 19 dic 2016, alle ore 16:20, Jens Axboe ha scritto: > > On 12/19/2016 04:32 AM, Paolo Valente wrote: >> >>> Il giorno 17 dic 2016, alle ore 01:12, Jens Axboe ha scritto: >>> >>> This is version 4 of this patchset, version 3 was posted here: >>> >>> https://marc.info/?l=linux-block&m=148178513407631&w=2 >>> >>> From the discussion last time, I looked into the feasibility of having >>> two sets of tags for the same request pool, to avoid having to copy >>> some of the request fields at dispatch and completion time. To do that, >>> we'd have to replace the driver tag map(s) with our own, and augment >>> that with tag map(s) on the side representing the device queue depth. >>> Queuing IO with the scheduler would allocate from the new map, and >>> dispatching would acquire the "real" tag. We would need to change >>> drivers to do this, or add an extra indirection table to map a real >>> tag to the scheduler tag. We would also need a 1:1 mapping between >>> scheduler and hardware tag pools, or additional info to track it. >>> Unless someone can convince me otherwise, I think the current approach >>> is cleaner. >>> >>> I wasn't going to post v4 so soon, but I discovered a bug that led >>> to drastically decreased merging. Especially on rotating storage, >>> this release should be fast, and on par with the merging that we >>> get through the legacy schedulers. >>> >> >> I'm to modifying bfq. You mentioned other missing pieces to come. Do >> you already have an idea of what they are, so that I am somehow >> prepared to what won't work even if my changes are right? > > I'm mostly talking about elevator ops hooks that aren't there in the new > framework, but exist in the old one. There should be no hidden > surprises, if that's what you are worried about. > > On the ops side, the only ones I can think of are the activate and > deactivate, and those can be done in the dispatch_request hook for > activate, and put/requeue for deactivate. > You mean that there is no conceptual problem in moving the code of the activate interface function into the dispatch function, and the code of the deactivate into the put_request? (for a requeue it is a little less clear to me, so one step at a time) Or am I missing something more complex? > Outside of that, some of them have been renamed, and some have been > collapsed (like activate/deactivate), and yet others again work a little > differently (like merging). See the mq-deadline conversion, and just > work through them one at the time. > That's how I'm proceeding, thanks. Thank you, Paolo > -- > Jens Axboe > > -- > To unsubscribe from this list: send the line "unsubscribe linux-block" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html