From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759375AbcCDSLY (ORCPT ); Fri, 4 Mar 2016 13:11:24 -0500 Received: from mail-qg0-f65.google.com ([209.85.192.65]:34765 "EHLO mail-qg0-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751080AbcCDSLW (ORCPT ); Fri, 4 Mar 2016 13:11:22 -0500 Subject: Re: [PATCH RFC 09/22] block, cfq: replace CFQ with the BFQ-v0 I/O scheduler To: Christoph Hellwig , Linus Walleij References: <1454364778-25179-1-git-send-email-paolo.valente@linaro.org> <1454364778-25179-10-git-send-email-paolo.valente@linaro.org> <20160211222210.GC3741@mtj.duckdns.org> <8FDE2B10-9BD2-4741-917F-5A37A74E5B58@linaro.org> <20160217170206.GU3741@mtj.duckdns.org> <72E81252-203C-4EB7-8459-B9B7060029C6@linaro.org> <20160301184656.GI3965@htj.duckdns.org> <20160304173947.GA16764@infradead.org> Cc: Tejun Heo , Paolo Valente , Jens Axboe , Fabio Checconi , Arianna Avanzini , linux-block@vger.kernel.org, "linux-kernel@vger.kernel.org" , Ulf Hansson , Mark Brown From: "Austin S. Hemmelgarn" Message-ID: <56D9CF97.7080005@gmail.com> Date: Fri, 4 Mar 2016 13:10:31 -0500 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:38.0) Gecko/20100101 Thunderbird/38.6.0 MIME-Version: 1.0 In-Reply-To: <20160304173947.GA16764@infradead.org> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit X-Antivirus: avast! (VPS 160304-0, 2016-03-04), Outbound message X-Antivirus-Status: Clean Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2016-03-04 12:39, Christoph Hellwig wrote: > On Sat, Mar 05, 2016 at 12:29:39AM +0700, Linus Walleij wrote: >> Hi Tejun, >> >> I'm doing a summary of this discussion as a part of presenting >> Linaro's involvement in Paolo's work. So I try to understand things. > > Btw, can someone explain why you guys waste so much time hacking and > arguing about a legacy codebase (old request code and I/O schedulers) > that everyone would really like to see disappear. Why don't you > spend your time on blk-mq where you have an entirely clean slate > for scheduling? > 1. This all started long before blk-mq hit mainline. 2. There's still a decent amount of block drivers that don't support blk-mq. Last time I looked (around the time 4.4 came out), I saw the following that either obviously don't support it, or are ambiguous as to whether they support it or not. Here's a list of just the ones I know are being used on existing systems running relatively recent kernel versions, not including any of the MTD stuff: * fd * MD * bcache * mmcblk * nbd * dasd * drbd * rbd * aoe * xvd (I know there were patches for this floating around, but I never saw if they got merged or not)