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 2ABAEC43334 for ; Fri, 22 Jul 2022 17:47:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235853AbiGVRrR (ORCPT ); Fri, 22 Jul 2022 13:47:17 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37998 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235855AbiGVRrQ (ORCPT ); Fri, 22 Jul 2022 13:47:16 -0400 Received: from mail-pl1-f176.google.com (mail-pl1-f176.google.com [209.85.214.176]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 246CC951CB; Fri, 22 Jul 2022 10:47:16 -0700 (PDT) Received: by mail-pl1-f176.google.com with SMTP id x1so3388226plb.3; Fri, 22 Jul 2022 10:47:16 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:message-id:date:mime-version:user-agent:subject :content-language:to:cc:references:from:in-reply-to :content-transfer-encoding; bh=iGdkXOH2H16F8Hpn2Tgy5CKP/LKypAMrDZQSY+JK7dU=; b=FADGIx/0gSkWSbFMchH2y99NWZJ9RLXrd8kuW+mL4qcrvK6U2oQe5/liUSYQ9JKW1I f+Qlq3GvnH168uOegqmqQ17p0nMn9DTqI7RYyJjmZ0TdSqQv3li6fGALFWOGRKUwBFz3 R1gyaaZsn1/lI1KaQgu47m62zN2yu9O0h7KgrqXATKCuEysyHFviYGdpRtqMgELQ91Nx iJ5ONf/nmv2FjSTJCeBZ+QUwDjfw+hSAVBJCD792oJH7BeKSKCRagmDV5VVUdTAeTlwp PXdM8Q1uuJ+GAehishKjaxzmNfCNUF8W/PcyRh+T1A9rUA75I4Cm5JlljcmvGrP4qGWT WQ0A== X-Gm-Message-State: AJIora8cv8w00zuHYEvg4A0W5xayHNzR5+1fIbM5Pe3rvlmYhlPeqNT2 y1inEdT6U5q3fYo06mLN69hqdIlKEac= X-Google-Smtp-Source: AGRyM1vBu7of+c3BIe4do/ZrLP7ttCauBZUaY+0hH7OjkwPbfvjhKrUFzo0woNgcxnLKLfR5odb3dQ== X-Received: by 2002:a17:90b:38c1:b0:1f1:f1c1:469c with SMTP id nn1-20020a17090b38c100b001f1f1c1469cmr18589427pjb.106.1658512035356; Fri, 22 Jul 2022 10:47:15 -0700 (PDT) Received: from ?IPV6:2620:15c:211:201:9cf6:7e29:d977:6fc7? ([2620:15c:211:201:9cf6:7e29:d977:6fc7]) by smtp.gmail.com with ESMTPSA id u8-20020a1709026e0800b001640aad2f71sm4013163plk.180.2022.07.22.10.47.13 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 22 Jul 2022 10:47:14 -0700 (PDT) Message-ID: Date: Fri, 22 Jul 2022 10:47:12 -0700 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.11.0 Subject: Re: [PATCH v2 2/2] block/mq-deadline: Prioritize first request Content-Language: en-US To: Wang You , axboe@kernel.dk Cc: linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, hch@lst.de, jaegeuk@kernel.org, fio@vger.kernel.org, ming.lei@redhat.com, wangxiaohua@uniontech.com References: <20220722095120.371212-1-wangyoua@uniontech.com> <20220722095120.371212-3-wangyoua@uniontech.com> From: Bart Van Assche In-Reply-To: <20220722095120.371212-3-wangyoua@uniontech.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On 7/22/22 02:51, Wang You wrote: > The test hardware is: > Kunpeng-920, HW-SAS3508+(MG04ACA400N * 2), RAID0. What is MG04ACA400N? The test results suggest that it is an SSD but this is something that should be mentioned explicitly. > - The test hardware is: > Hygon C86, MG04ACA400N What is MG04ACA400N? > The test command is: > fio -ioengine=psync -lockmem=1G -buffered=0 -time_based=1 -direct=1 -iodepth=1 > -thread -bs=512B -size=110g -numjobs=32 -runtime=300 -group_reporting > -name=read -filename=/dev/sdc -ioscheduler=mq-deadline -rw=read[,write,rw] > > The following is the test data: > origin/master: > read iops: 15463 write iops: 5949 rw iops: 574,576 > > nr_sched_batch = 1: > read iops: 15082 write iops: 6283 rw iops: 783,786 > > nr_sched_batch = 1, use deadline_head_request: > read iops: 15368 write iops: 6575 rw iops: 907,906 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? Thanks, Bart.