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=-2.2 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 89881C74A23 for ; Wed, 10 Jul 2019 14:00:44 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 5F7ED2087F for ; Wed, 10 Jul 2019 14:00:44 +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="yBfEFr7y" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727734AbfGJOAn (ORCPT ); Wed, 10 Jul 2019 10:00:43 -0400 Received: from mail-io1-f66.google.com ([209.85.166.66]:46974 "EHLO mail-io1-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726080AbfGJOAn (ORCPT ); Wed, 10 Jul 2019 10:00:43 -0400 Received: by mail-io1-f66.google.com with SMTP id i10so4836248iol.13 for ; Wed, 10 Jul 2019 07:00:43 -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=uLDn6FoYIxeReECmo+TpeGDmidMAcbRcZrkscc5kAsA=; b=yBfEFr7yxFpc6DuLLhXX1DAnqM9459BahEd2QCdjUtR5LTkk0OkpSWz/fNDJPqZ4Eg 2O4/HATSD/igFfddXASCAJVmsldwe8lNWqsG4hIrcHXjj/bwIQNoaI/EbRDHZs/qAIHn G1FGuLdmry9IhxGlnOHoqXumoDhViWnwqstnQuBBJ12fpcr88XR5UMkm1KEpBBbAp1JI xsZ7c6DcoArYJqldQY38wvwrnxUe9hdruIqxrAEUMgCSXGFcGoOFvcK8KnPAciKrOB0z AzPwRKYSRI70y3/eNOrDzmV936ihA+a11hwpyy1kfkjhTJPO/FSBfYuA/jiqpbVNU1gI IcIg== 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=uLDn6FoYIxeReECmo+TpeGDmidMAcbRcZrkscc5kAsA=; b=rVtQSlplj83NqPk9ehRas9mq/29nbQHFqhZW12DT61e8bJE0djCHH8iPtzPBQc/4ZH JrzV+JXJgPKZztTfs3u7+9U6bU4vdMHUzU8aSEdO0oLgaNcMQ94cdaGJGNyXthx+shRl 99HfBAX3uX+fnQJY8wLhtM9llWEqqrWTy6eQCZB2yM08x60ecbZ6zjhWh17LT274IKhV PKfejGm6iB+J9mI6raB+XDhJOIUFqcTjMthoLWTiYtgYiQS7atFHQ4Tx6iagpG42lhjT Ja0EIdAgEbXFtZTjScj7IGB6w7A1Ty0UsHg5j0qLFeIHuRKITRoRjgaUI5rJXBmfeSZ5 CLZg== X-Gm-Message-State: APjAAAUSC+x6brXa3qmFZaDWrvaiwW6KndAWrYuGfzZj7X/LNeEKsaQG WGsZhBXWgjHl7L25fojpQrxBUA== X-Google-Smtp-Source: APXvYqy7gIMHIZKeU3ZjEjuVffpS1YJvkAOw7HV+TgJseYlld/VwQmsqw+3UihClAvATVA1ZPifRlw== X-Received: by 2002:a6b:ed02:: with SMTP id n2mr18863623iog.131.1562767242821; Wed, 10 Jul 2019 07:00:42 -0700 (PDT) Received: from [192.168.1.158] ([65.144.74.34]) by smtp.gmail.com with ESMTPSA id t133sm3887077iof.21.2019.07.10.07.00.41 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 10 Jul 2019 07:00:41 -0700 (PDT) Subject: Re: [PATCH] blk-throttle: fix zero wait time for iops throttled group To: Konstantin Khlebnikov , linux-block@vger.kernel.org, linux-kernel@vger.kernel.org Cc: Liu Bo , stable@vger.kernel.org References: <156259979778.2486.6296077059654653057.stgit@buzz> From: Jens Axboe Message-ID: <30caacb5-4d45-016b-a97d-db8b37010218@kernel.dk> Date: Wed, 10 Jul 2019 08:00:40 -0600 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.7.2 MIME-Version: 1.0 In-Reply-To: <156259979778.2486.6296077059654653057.stgit@buzz> 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 7/8/19 9:29 AM, Konstantin Khlebnikov wrote: > After commit 991f61fe7e1d ("Blk-throttle: reduce tail io latency when iops > limit is enforced") wait time could be zero even if group is throttled and > cannot issue requests right now. As a result throtl_select_dispatch() turns > into busy-loop under irq-safe queue spinlock. > > Fix is simple: always round up target time to the next throttle slice. Applied, thanks. In the future, please break lines at 72 chars in commit messages, I fixed it up. -- Jens Axboe