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[209.132.180.67]) by mx.google.com with ESMTP id m5si22507476pgc.136.2019.05.21.15.52.19; Tue, 21 May 2019 15:52:44 -0700 (PDT) Received-SPF: pass (google.com: best guess record for domain of linux-ext4-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; spf=pass (google.com: best guess record for domain of linux-ext4-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-ext4-owner@vger.kernel.org; dmarc=fail (p=NONE sp=NONE dis=NONE) header.from=csail.mit.edu Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726466AbfEUWwT (ORCPT + 99 others); Tue, 21 May 2019 18:52:19 -0400 Received: from outgoing-stata.csail.mit.edu ([128.30.2.210]:41586 "EHLO outgoing-stata.csail.mit.edu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726218AbfEUWwS (ORCPT ); Tue, 21 May 2019 18:52:18 -0400 Received: from [4.30.142.84] (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 1hTDbq-0003mv-2S; Tue, 21 May 2019 18:52:13 -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> From: "Srivatsa S. Bhat" Message-ID: <0e3fdf31-70d9-26eb-7b42-2795d4b03722@csail.mit.edu> Date: Tue, 21 May 2019 15:51:46 -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-ext4-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-ext4@vger.kernel.org [ 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 Thank you! Regards, Srivatsa VMware Photon OS