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 37C8EC00528 for ; Mon, 24 Jul 2023 15:50:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231396AbjGXPue (ORCPT ); Mon, 24 Jul 2023 11:50:34 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60714 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231203AbjGXPua (ORCPT ); Mon, 24 Jul 2023 11:50:30 -0400 Received: from mail-io1-xd31.google.com (mail-io1-xd31.google.com [IPv6:2607:f8b0:4864:20::d31]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id EC29610D for ; Mon, 24 Jul 2023 08:50:25 -0700 (PDT) Received: by mail-io1-xd31.google.com with SMTP id ca18e2360f4ac-760dff4b701so56076839f.0 for ; Mon, 24 Jul 2023 08:50:25 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel-dk.20221208.gappssmtp.com; s=20221208; t=1690213825; x=1690818625; h=content-transfer-encoding:in-reply-to:from:references:cc:to :content-language:subject:user-agent:mime-version:date:message-id :from:to:cc:subject:date:message-id:reply-to; bh=RIsGgKww9Eb9PV4fKcvrXzf2hZ8SDdRIJ2lqhbJPbJQ=; b=owmGOTF+NRNxB4d7mwEMH/srf6ZO86sCeA9RYlA2xU+3tARUIMj5MSrcFV+blaqX2T h/DNPpYOOivTX8NaHKjWzGenwwSPRcvvqW+Tk+qdppXYRyjBhVYx4f3RPR+PhAySz7qb +lXyGwJqDiCsovfQ9A68Uhf5enWmzwFRHhiZ4jEqtH4LLhYvRMtKRvmZxx7j5nNcua3f m68WS24q4UwLYVAj6e4Z0zZ8qUErgBzfvjoBfFOkeSFkPK/cscV7C5OMsIu+zFbG9M8t AwFRyzE6T87xjDBXixmz6psfFGuszmC8UmbWlCoXuJ+OoLHxwxXKzUHgOIElucUcWpQ+ Jqng== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1690213825; x=1690818625; h=content-transfer-encoding:in-reply-to:from:references:cc:to :content-language:subject:user-agent:mime-version:date:message-id :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=RIsGgKww9Eb9PV4fKcvrXzf2hZ8SDdRIJ2lqhbJPbJQ=; b=hWp0f4KopXvZSnZEkUSsD455gOFxw2Up8hpFJdpNbx8QVfV6LKVrPIHpFTIzfxb20U iYEkoK10YSuxoOEpujWILDFXcsVm75npdS8ZJJrAH+Xxy24vOLFYT2r21Uv5xbncedH+ 4efAEKqM1tslo8dWq5DeQwYhbciiekUBYj/jcRGoO+O1Xx/AV8+/+o0ODaJH4hmcAUZt 6zfRJPq0a9EVO2bcM64jBv0eQRPro+yHuZYWzFFuUPA8Yhv5IOfQHTJvIzzxL+z1yY/g Ax/vO2BkHjWb7Iej9OdwqfpXAI3RiCuLd7WtxiiKBgiSYfxheUw2Gbw0DcrFeFaO4/Sz TYmw== X-Gm-Message-State: ABy/qLZxPLk6X3SAPxd0qm8U/i/BxB7T2BX2ggbnTY0URwg9yAQNLZtm H66snEUaBpONYkagjpwzmVICyQ== X-Google-Smtp-Source: APBJJlHXzYYl5MkD6ZjEsZRCsiXpMK0FkxLXK+k8wkt+S6Et1/6HEGKXVp0UJrNVR8gc854pfJh2nA== X-Received: by 2002:a05:6602:3e87:b0:780:cb36:6f24 with SMTP id el7-20020a0566023e8700b00780cb366f24mr8220438iob.2.1690213825340; Mon, 24 Jul 2023 08:50:25 -0700 (PDT) Received: from [192.168.1.94] ([96.43.243.2]) by smtp.gmail.com with ESMTPSA id t23-20020a05663801f700b00420e6c58971sm3008295jaq.178.2023.07.24.08.50.24 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 24 Jul 2023 08:50:24 -0700 (PDT) Message-ID: <140065e3-0368-0b5d-8a0d-afe49b741ad2@kernel.dk> Date: Mon, 24 Jul 2023 09:50:24 -0600 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux aarch64; rv:102.0) Gecko/20100101 Thunderbird/102.13.0 Subject: Re: [PATCH] io_uring: Use io_schedule* in cqring wait Content-Language: en-US To: Greg KH , Phil Elwell Cc: andres@anarazel.de, asml.silence@gmail.com, david@fromorbit.com, hch@lst.de, io-uring@vger.kernel.org, LKML , linux-xfs@vger.kernel.org, stable References: <2023072438-aftermath-fracture-3dff@gregkh> From: Jens Axboe In-Reply-To: <2023072438-aftermath-fracture-3dff@gregkh> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 7/24/23 9:48?AM, Greg KH wrote: > On Mon, Jul 24, 2023 at 04:35:43PM +0100, Phil Elwell wrote: >> Hi Andres, >> >> With this commit applied to the 6.1 and later kernels (others not >> tested) the iowait time ("wa" field in top) in an ARM64 build running >> on a 4 core CPU (a Raspberry Pi 4 B) increases to 25%, as if one core >> is permanently blocked on I/O. The change can be observed after >> installing mariadb-server (no configuration or use is required). After >> reverting just this commit, "wa" drops to zero again. > > This has been discussed already: > https://lore.kernel.org/r/12251678.O9o76ZdvQC@natalenko.name > > It's not a bug, mariadb does have pending I/O, so the report is correct, > but the CPU isn't blocked at all. Indeed - only thing I can think of is perhaps mariadb is having a separate thread waiting on the ring in perpetuity, regardless of whether or not it currently has IO. But yes, this is very much ado about nothing... -- Jens Axboe