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=-1.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=ham 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 AB890C18E7D for ; Wed, 22 May 2019 09:02:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 89FC3205ED for ; Wed, 22 May 2019 09:02:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728940AbfEVJCs (ORCPT ); Wed, 22 May 2019 05:02:48 -0400 Received: from outgoing-stata.csail.mit.edu ([128.30.2.210]:47935 "EHLO outgoing-stata.csail.mit.edu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727946AbfEVJCs (ORCPT ); Wed, 22 May 2019 05:02:48 -0400 Received: from c-73-193-85-113.hsd1.wa.comcast.net ([73.193.85.113] helo=srivatsab-a01.vmware.com) by outgoing-stata.csail.mit.edu with esmtpsa (TLS1.2:RSA_AES_128_CBC_SHA1:128) (Exim 4.82) (envelope-from ) id 1hTN8z-0009cO-OQ; Wed, 22 May 2019 05:02:41 -0400 Subject: Re: CFQ idling kills I/O performance on ext4 with blkio cgroup controller To: Paolo Valente Cc: linux-fsdevel@vger.kernel.org, linux-block , linux-ext4@vger.kernel.org, cgroups@vger.kernel.org, kernel list , Jens Axboe , Jan Kara , jmoyer@redhat.com, Theodore Ts'o , amakhalov@vmware.com, anishs@vmware.com, srivatsab@vmware.com References: <8d72fcf7-bbb4-2965-1a06-e9fc177a8938@csail.mit.edu> <1812E450-14EF-4D5A-8F31-668499E13652@linaro.org> <46c6a4be-f567-3621-2e16-0e341762b828@csail.mit.edu> <07D11833-8285-49C2-943D-E4C1D23E8859@linaro.org> <5B6570A2-541A-4CF8-98E0-979EA6E3717D@linaro.org> <2CB39B34-21EE-4A95-A073-8633CF2D187C@linaro.org> <0e3fdf31-70d9-26eb-7b42-2795d4b03722@csail.mit.edu> From: "Srivatsa S. Bhat" Message-ID: Date: Wed, 22 May 2019 02:02:33 -0700 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.13; rv:60.0) Gecko/20100101 Thunderbird/60.6.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=windows-1252 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 5/22/19 1:05 AM, Paolo Valente wrote: > > >> Il giorno 22 mag 2019, alle ore 00:51, Srivatsa S. Bhat ha scritto: >> >> [ Resending this mail with a dropbox link to the traces (instead >> of a file attachment), since it didn't go through the last time. ] >> >> On 5/21/19 10:38 AM, Paolo Valente wrote: >>> >>>> So, instead of only sending me a trace, could you please: >>>> 1) apply this new patch on top of the one I attached in my previous email >>>> 2) repeat your test and report results >>> >>> One last thing (I swear!): as you can see from my script, I tested the >>> case low_latency=0 so far. So please, for the moment, do your test >>> with low_latency=0. You find the whole path to this parameter in, >>> e.g., my script. >>> >> No problem! :) Thank you for sharing patches for me to test! >> >> I have good news :) Your patch improves the throughput significantly >> when low_latency = 0. >> >> Without any patch: >> >> dd if=/dev/zero of=/root/test.img bs=512 count=10000 oflag=dsync >> 10000+0 records in >> 10000+0 records out >> 5120000 bytes (5.1 MB, 4.9 MiB) copied, 58.0915 s, 88.1 kB/s >> >> >> With both patches applied: >> >> dd if=/dev/zero of=/root/test0.img bs=512 count=10000 oflag=dsync >> 10000+0 records in >> 10000+0 records out >> 5120000 bytes (5.1 MB, 4.9 MiB) copied, 3.87487 s, 1.3 MB/s >> >> The performance is still not as good as mq-deadline (which achieves >> 1.6 MB/s), but this is a huge improvement for BFQ nonetheless! >> >> A tarball with the trace output from the 2 scenarios you requested, >> one with only the debug patch applied (trace-bfq-add-logs-and-BUG_ONs), >> and another with both patches applied (trace-bfq-boost-injection) is >> available here: >> >> https://www.dropbox.com/s/pdf07vi7afido7e/bfq-traces.tar.gz?dl=0 >> > > Hi Srivatsa, > I've seen the bugzilla you've created. I'm a little confused on how > to better proceed. Shall we move this discussion to the bugzilla, or > should we continue this discussion here, where it has started, and > then update the bugzilla? > Let's continue here on LKML itself. The only reason I created the bugzilla entry is to attach the tarball of the traces, assuming that it would allow me to upload a 20 MB file (since email attachment didn't work). But bugzilla's file restriction is much smaller than that, so it didn't work out either, and I resorted to using dropbox. So we don't need the bugzilla entry anymore; I might as well close it to avoid confusion. Regards, Srivatsa VMware Photon OS