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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 53A41C43334 for ; Sat, 23 Jul 2022 10:59:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230399AbiGWK7l (ORCPT ); Sat, 23 Jul 2022 06:59:41 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34478 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239375AbiGWK7k (ORCPT ); Sat, 23 Jul 2022 06:59:40 -0400 Received: from smtpbgjp3.qq.com (smtpbgjp3.qq.com [54.92.39.34]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 0CE5D26130 for ; Sat, 23 Jul 2022 03:59:38 -0700 (PDT) X-QQ-mid: bizesmtp79t1658573961tz10fe20 Received: from eureka.localdomain ( [123.124.208.226]) by bizesmtp.qq.com (ESMTP) with id ; Sat, 23 Jul 2022 18:59:09 +0800 (CST) X-QQ-SSF: 01400000002000B0D000B00A0000020 X-QQ-FEAT: 4rCmCcmdMHfwis57XlYAPZfJdHJIxkKNcwfR4eFB0vZN/Pzx6uJfciJh7n054 lVJvDLJ+negW15WQMWccV6GExZ/LlNYWlxKKf3+qMYqLuvwQ/D3boqidj+aiShvFxaZgme2 4kn+D+afWkNCf4eoZPf0ziVTYWv7hWET0Yvt2Ypv5hgwvsO36g3TVzxjNcG/JBs/J/DZPma NVGfCJ5EGrrdM+4QVPMm9RqPhirigUk8UMqTNj1fG2hzu7QrbDcxKjzLjsI9gfNVLAr4zHl N4hNDAprzRHmzRT5Zu4eserDeuXbo4jvk+McsmlEcBwHsCr9sP+38bmR2U5PdLUZmqSdWcI rErMgv8rUAwPaH4Tc3oYAlBjZDZ6QWxHb3v77Zk+qVEbcKMT9dWpS1b4KBR3Ff0DE3t7Vic X-QQ-GoodBg: 2 From: Wang You To: bvanassche@acm.org Cc: axboe@kernel.dk, fio@vger.kernel.org, hch@lst.de, jaegeuk@kernel.org, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, ming.lei@redhat.com, wangxiaohua@uniontech.com, wangyoua@uniontech.com Subject: Re: [PATCH v2 2/2] block/mq-deadline: Prioritize first request Date: Sat, 23 Jul 2022 18:59:09 +0800 Message-Id: <20220723105909.440050-1-wangyoua@uniontech.com> X-Mailer: git-send-email 2.27.0 In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-QQ-SENDSIZE: 520 Feedback-ID: bizesmtp:uniontech.com:qybgforeign:qybgforeign3 X-QQ-Bgrelay: 1 Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org > What is MG04ACA400N? It is a Toshiba 7200 RPM hard drive. > The above results are low enough such that these could come from a hard > disk. However, the test results are hard to interpret since the I/O > pattern is neither perfectly sequential nor perfectly random (32 > sequential jobs). Please provide separate measurements for sequential > and random I/O. > The above results show that this patch makes reading from a hard disk > slower. Isn't the primary use case of mq-deadline to make reading from > hard disks faster? So why should these two patches be applied if these > slow down reading from a hard disk? The data of MG04ACA400N on the raid controller is obviously different from the single disk, especially the reading data, I did not expect this situation, the data on the raid controller made me mistakenly think that the same applies to HDD. I will re-analyze the impact of this patch on the HDD later, please ignore it for now. Also, can I ask? If using fio or other tools, how should testing be done to get more accurate and convincing data? Such as the perfectly sequential and random I/O performance you mentioned above (fio's multi-threaded test does result in neither perfectly sequential nor perfectly random, but single thread dispatch is too slow, and cannot play the merge and sorting ability of elv). Thanks, Wang.