From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_MUTT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id DA84FC46477 for ; Wed, 12 Jun 2019 13:04:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id BF23A20866 for ; Wed, 12 Jun 2019 13:04:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731622AbfFLNEt (ORCPT ); Wed, 12 Jun 2019 09:04:49 -0400 Received: from mx2.suse.de ([195.135.220.15]:55104 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1728322AbfFLNEs (ORCPT ); Wed, 12 Jun 2019 09:04:48 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id D5E70AF8F; Wed, 12 Jun 2019 13:04:46 +0000 (UTC) Received: by quack2.suse.cz (Postfix, from userid 1000) id 1FBB21E4328; Wed, 12 Jun 2019 15:04:46 +0200 (CEST) Date: Wed, 12 Jun 2019 15:04:46 +0200 From: Jan Kara To: "Srivatsa S. Bhat" Cc: Paolo Valente , linux-fsdevel@vger.kernel.org, linux-block , linux-ext4@vger.kernel.org, cgroups@vger.kernel.org, kernel list , Jens Axboe , Jan Kara , Jeff Moyer , Theodore Ts'o , amakhalov@vmware.com, anishs@vmware.com, srivatsab@vmware.com, Ulf Hansson , Linus Walleij Subject: Re: CFQ idling kills I/O performance on ext4 with blkio cgroup controller Message-ID: <20190612130446.GD14578@quack2.suse.cz> References: <6FE0A98F-1E3D-4EF6-8B38-2C85741924A4@linaro.org> <2A58C239-EF3F-422B-8D87-E7A3B500C57C@linaro.org> <5b71028c-72f0-73dd-0cd5-f28ff298a0a3@csail.mit.edu> <0d6e3c02-1952-2177-02d7-10ebeb133940@csail.mit.edu> <7B74A790-BD98-412B-ADAB-3B513FB1944E@linaro.org> <6a6f4aa4-fc95-f132-55b2-224ff52bd2d8@csail.mit.edu> <7c5e9d11-4a3d-7df4-c1e6-7c95919522ab@csail.mit.edu> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <7c5e9d11-4a3d-7df4-c1e6-7c95919522ab@csail.mit.edu> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue 11-06-19 15:34:48, Srivatsa S. Bhat wrote: > On 6/2/19 12:04 AM, Srivatsa S. Bhat wrote: > > On 5/30/19 3:45 AM, Paolo Valente wrote: > >> > [...] > >> At any rate, since you pointed out that you are interested in > >> out-of-the-box performance, let me complete the context: in case > >> low_latency is left set, one gets, in return for this 12% loss, > >> a) at least 1000% higher responsiveness, e.g., 1000% lower start-up > >> times of applications under load [1]; > >> b) 500-1000% higher throughput in multi-client server workloads, as I > >> already pointed out [2]. > >> > > > > I'm very happy that you could solve the problem without having to > > compromise on any of the performance characteristics/features of BFQ! > > > > > >> I'm going to prepare complete patches. In addition, if ok for you, > >> I'll report these results on the bug you created. Then I guess we can > >> close it. > >> > > > > Sounds great! > > > > Hi Paolo, > > Hope you are doing great! > > I was wondering if you got a chance to post these patches to LKML for > review and inclusion... (No hurry, of course!) > > Also, since your fixes address the performance issues in BFQ, do you > have any thoughts on whether they can be adapted to CFQ as well, to > benefit the older stable kernels that still support CFQ? Since CFQ doesn't exist in current upstream kernel anymore, I seriously doubt you'll be able to get any performance improvements for it in the stable kernels... Honza -- Jan Kara SUSE Labs, CR