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=-4.1 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED 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 4EE65C433DF for ; Wed, 29 Jul 2020 09:49:50 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2AFEB2076E for ; Wed, 29 Jul 2020 09:49:50 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="Fc2pBAa8" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726724AbgG2Jts (ORCPT ); Wed, 29 Jul 2020 05:49:48 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44894 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726208AbgG2Jts (ORCPT ); Wed, 29 Jul 2020 05:49:48 -0400 Received: from mail-ed1-x541.google.com (mail-ed1-x541.google.com [IPv6:2a00:1450:4864:20::541]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id BCA60C061794 for ; Wed, 29 Jul 2020 02:49:47 -0700 (PDT) Received: by mail-ed1-x541.google.com with SMTP id v22so6165146edy.0 for ; Wed, 29 Jul 2020 02:49:47 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=NCwve/GSQ0PM+VLoVzHp74iG5IouH+0k4NcSwjdJu78=; b=Fc2pBAa8fbNxmY+4xmemVrmZVCTuQMhNhCbW9wIMS8v32lNz8SCsUO3P4uT8XZTD7H UfOMDWV9+hji2skyLGWySFfDBGVBluIO/pQKX+OyBdH6hdT8iaPw3hhsScy/fb4bW9Gs FDH7SvMayNU74z69bEo+4zbNfV+f8kRdwIFbElE0fNYvibwXClMc/4jbuDxxpUyP1/N9 SxJ1zqTIsvgLrTJWApi96EyuUR4ecRhQ+20QfWezs/nAn34a6FR1By77oUKtI2Crova7 d14B7JjEo2phbF/C5BZr5EUc0TvCEkvPi+7tMk7Mvrabee6m2ZEZnhn2fPtXguEttguj 41tg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=NCwve/GSQ0PM+VLoVzHp74iG5IouH+0k4NcSwjdJu78=; b=k+f/kl8EoC7D2YtrakqAZdJaIeLDz8jtKH5SxWzAQDzFvHM5WodfABodHW5SzDDSzZ 1HgLzrSh0GLaSnp/FDN1caVVunKXL+5hpVNfgySwKyZQMS8R2rh7AUyyPbh2gJHVPp0K zty2iKUD1+HwWG2wNAEboEAM3NtadTajeymvc54sFFz+97P3GWSGSUoGcOSL2eFsbM3I P7XeO3H/+VkevtJLKqU5LjaDKutJpr/u0gTKCQdiMUgm9urZZdIVg59ungQD/BneH32I eYj/+HDMAD8cneZO40dUwLfkzWKnyqhF55yEiHlNYDuz1yIj4Zc/00lxbs41FYVvyAMf N7GQ== X-Gm-Message-State: AOAM530zOpj4bYWYKOdCwqS/nAe9HKN6k4fHBAXh5jRXYYtntz0kAxOv oIPGz7ReWg5wEYW0h0a320M= X-Google-Smtp-Source: ABdhPJyC58IUur3BWYx2xe8F1hYV3okkEL1hWUX1g9eJPglxm6FBxyNRg5VFD2C5/DpvVGuB9Dd/Mg== X-Received: by 2002:a05:6402:1687:: with SMTP id a7mr29689719edv.358.1596016186516; Wed, 29 Jul 2020 02:49:46 -0700 (PDT) Received: from skbuf ([188.25.95.40]) by smtp.gmail.com with ESMTPSA id m24sm1142659eje.80.2020.07.29.02.49.45 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 29 Jul 2020 02:49:45 -0700 (PDT) Date: Wed, 29 Jul 2020 12:49:43 +0300 From: Vladimir Oltean To: Kurt Kanzenbach Cc: Alison Wang , catalin.marinas@arm.com, will@kernel.org, paulmck@kernel.org, mw@semihalf.com, leoyang.li@nxp.com, vladimir.oltean@nxp.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Thomas Gleixner , Anna-Maria Gleixner Subject: Re: [RFC PATCH] arm64: defconfig: Disable fine-grained task level IRQ time accounting Message-ID: <20200729094943.lsmhsqlnl7rlnl6f@skbuf> References: <20200729033934.22349-1-alison.wang@nxp.com> <877dumbtoi.fsf@kurt> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <877dumbtoi.fsf@kurt> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Jul 29, 2020 at 10:40:29AM +0200, Kurt Kanzenbach wrote: > Hi Alison, > > On Wed Jul 29 2020, Alison Wang wrote: > > In the current arm64 defconfig, CONFIG_IRQ_TIME_ACCOUNTING is enabled as > > default. According to my tests on NXP's LayerScape and i.MX platforms, > > the system hangs when running the command "stress-ng --hrtimers 1" with > > CONFIG_IRQ_TIME_ACCOUNTING enabled. Disabling this option, the issue > > disappears. CONFIG_IRQ_TIME_ACCOUNTING causes serious performance impact > > when running hrtimer stress test at the same time. > > I think instead of disabling the option for all arm64 devices, it might > be better to analyze the root-cause why the hrtimer test hangs when this > option is enabled. > > +Cc hrtimer maintainers: Thomas and Anna-Maria > > Thanks, > Kurt For more context, here is my original report of the issue: https://lkml.org/lkml/2020/6/4/1062 Just like you, I could not reproduce the RCU stalls and system hang on a 5.6-rt kernel, just on mainline and derivatives, using the plain defconfig. The issue is not specific to Layerscape or i.MX8, but rather I was able to see the same behavior on Marvell Armada 37xx as well as Qualcomm MSM8976. So, while of course I agree that disabling IRQ time accounting for arm64 isn't a real solution, it isn't by far an exaggerated proposal either. Nonetheless, the patch is just a RFC and should be treated as such. We are at a loss when it comes to debugging this any further and we would appreciate some pointers. Thanks, -Vladimir