From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754952AbdBVSoy (ORCPT ); Wed, 22 Feb 2017 13:44:54 -0500 Received: from mail-it0-f44.google.com ([209.85.214.44]:38590 "EHLO mail-it0-f44.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754765AbdBVSon (ORCPT ); Wed, 22 Feb 2017 13:44:43 -0500 Subject: Re: [GIT PULL] Block pull request for- 4.11-rc1 To: Linus Torvalds References: <6d5d4b2b-5343-09ff-72c3-4e9a7e591d68@kernel.dk> Cc: "linux-block@vger.kernel.org" , "linux-kernel@vger.kernel.org" From: Jens Axboe Message-ID: Date: Wed, 22 Feb 2017 11:44:41 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.7.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 02/22/2017 11:42 AM, Linus Torvalds wrote: > On Wed, Feb 22, 2017 at 10:26 AM, Linus Torvalds > wrote: >> >> And dammit, IF YOU DON'T EVEN KNOW, WHY THE HELL ARE YOU ASKING THE POOR USER? > > Basically, I'm pushing back on config options that I can't personally > even sanely answer. I got that much, and I don't disagree on that part. > If it's a config option about "do I have a particular piece of > hardware", it makes sense. But these new ones were just complete > garbage. > > The whole "default IO scheduler" thing is a disease. We should stop > making up these shit schedulers and then say "we don't know which one > works best for you". > > All it does is encourage developers to make shortcuts and create crap > that isn't generically useful, and then blame the user and say "well, > you should have picked a different scheduler" when they say "this does > not work well for me". > > We have had too many of those kinds of broken choices. And when the > new Kconfig options get so confusing and so esoteric that I go "Hmm, I > have no idea if my hardware does a single queue or not", I put my foot > down. > > When the IO scheduler questions were about a generic IO scheduler for > everything, I can kind of understand them. I think it was still a > mistake (for the reasons outline above), but at least it was a > comprehensible question to ask. > > But when it gets to "what should I do about a single-queue version of > a MQ scheduler", the question is no longer even remotely sensible. The > question should simply NOT EXIST. There is no possible valid reason to > ask that kind of crap. OK, so here's what I'll do: 1) We'll kill the default scheduler choices. sq blk-mq will default to mq-deadline, mq blk-mq will default to "none" (at least for now, until the new scheduler is done). 2) The individual schedulers will be y/m/n selectable, just like any other driver. I hope that works for everyone. -- Jens Axboe