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=-2.3 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=no 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 974A2C4360C for ; Sun, 6 Oct 2019 15:25:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 6A43B20862 for ; Sun, 6 Oct 2019 15:25:15 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=kernel-dk.20150623.gappssmtp.com header.i=@kernel-dk.20150623.gappssmtp.com header.b="oiPn/7Yc" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1725905AbfJFPZO (ORCPT ); Sun, 6 Oct 2019 11:25:14 -0400 Received: from mail-pf1-f194.google.com ([209.85.210.194]:46351 "EHLO mail-pf1-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725847AbfJFPZO (ORCPT ); Sun, 6 Oct 2019 11:25:14 -0400 Received: by mail-pf1-f194.google.com with SMTP id q5so6979804pfg.13 for ; Sun, 06 Oct 2019 08:25:14 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel-dk.20150623.gappssmtp.com; s=20150623; h=subject:to:cc:references:from:message-id:date:user-agent :mime-version:in-reply-to:content-language:content-transfer-encoding; bh=maJ2FXUCg8vNkIizMO50NGsfFdPFdqKAiECAgvNp/ME=; b=oiPn/7YcBsRQyH1m/o+ETLvChQAdxdByZa6uPg9dghglLTKuk8iK7E7dz/0cBdYP/h o6u/FKXk4IRukpUP8piLKMTp7Y3+PNIGBTAV/KkdOoI5u3G/tHnd7QbzpqAhiI3+stwv j0ZPgkax6D6arn/xL57cMLwrXMYcVLw3w/2lj/PV3YOoHp2AwIl3KGmVjDsFgVdYuetS kDIvfW55rsfcpG0a+W9ZVpAdNU0RtmSWlldZrKsl5kB7PVej5y86fzOp24YQ7wkSrWet 10Ei4/QMnJp5GM33T02Sr2W9eZIurqgR40JSukllX0Xz2GLZlk0MPZEVyWDwGIiruF7P x8Vw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=maJ2FXUCg8vNkIizMO50NGsfFdPFdqKAiECAgvNp/ME=; b=RwYfEJzPXo8Q1ejzCOaj8ucpY2EBBvTNWiwJF0mOZALoEe8tEOz5ICnKoPZXrZkvuu sPFf07oW5glaWDjQK8s6c60Y23vmpDtH97q5fRMJcT92sH019PM2DtrsFq+f6iJg3tLG y60gM+i92/qo1lxNFMQ01NNKONWmLRsORllVYEI3zx6jlk2NKrQ/9sPCL6WPaumR/dh/ GcKEu2BcR9C9u1V5fKqk3lE1RU7lJ0gVrRMDK6nmW+5V1FF0QOVV9NfiNaEWSgyXB6Jc S6ROU7ZNpbVvBtmym+PM2OSey6iW60bJIeQQWhpQ+zlBHv16gBD8zzzb1ztZqFGNnvK8 FIJA== X-Gm-Message-State: APjAAAV9hLPUshodpfbx7ZQ8tnP2E9ZV1tnzW97ls0Ld1Aua4C7KZSqa mrJuizoTqIM7JUDjttdZX1ykQg== X-Google-Smtp-Source: APXvYqzHazVz0k/u0XRHI2W+hvULlIv9e2Zz2FJVED4yPo2Hl4hn6DDIvvhQvzVC67GiZzIv9OiTNA== X-Received: by 2002:a17:90a:ae0d:: with SMTP id t13mr28703621pjq.60.1570375513877; Sun, 06 Oct 2019 08:25:13 -0700 (PDT) Received: from [192.168.1.188] ([66.219.217.79]) by smtp.gmail.com with ESMTPSA id d6sm14536552pgj.22.2019.10.06.08.25.11 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Sun, 06 Oct 2019 08:25:13 -0700 (PDT) Subject: Re: [PATCH v2] blk-wbt: fix performance regression in wbt scale_up/scale_down To: Harshad Shirwadkar , linux-kernel@vger.kernel.org Cc: linux-block@vger.kernel.org, vaibhavrustagi@google.com, Josef Bacik References: <20191005185927.91209-1-harshadshirwadkar@gmail.com> From: Jens Axboe Message-ID: <946f4a47-c4ad-0b2e-4a5b-d0873cbcb510@kernel.dk> Date: Sun, 6 Oct 2019 09:25:10 -0600 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: <20191005185927.91209-1-harshadshirwadkar@gmail.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On 10/5/19 12:59 PM, Harshad Shirwadkar wrote: > scale_up wakes up waiters after scaling up. But after scaling max, it > should not wake up more waiters as waiters will not have anything to > do. This patch fixes this by making scale_up (and also scale_down) > return when threshold is reached. > > This bug causes increased fdatasync latency when fdatasync and dd > conv=sync are performed in parallel on 4.19 compared to 4.14. This > bug was introduced during refactoring of blk-wbt code. Nice catch, thanks, applied. -- Jens Axboe