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 3E563C7EE23 for ; Fri, 5 May 2023 02:36:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229459AbjEECgL (ORCPT ); Thu, 4 May 2023 22:36:11 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39356 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229472AbjEECgK (ORCPT ); Thu, 4 May 2023 22:36:10 -0400 Received: from mail-pf1-x42e.google.com (mail-pf1-x42e.google.com [IPv6:2607:f8b0:4864:20::42e]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3CD8C120B2; Thu, 4 May 2023 19:35:55 -0700 (PDT) Received: by mail-pf1-x42e.google.com with SMTP id d2e1a72fcca58-6439b410679so456649b3a.0; Thu, 04 May 2023 19:35:55 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20221208; t=1683254155; x=1685846155; h=in-reply-to:references:to:from:subject:cc:message-id:date :content-transfer-encoding:mime-version:from:to:cc:subject:date :message-id:reply-to; bh=evsRyVdUpm9tZ3zbpYtyLZiIFPAu7MWLlo8c04t+4vY=; b=bPL3OQA2wcMMOXheYlA8QxViGjC7iCOlxPhX4fuvTbvsINcXnCzBLieoUCDzT+56/k 9oa+q6KgEYTU31LDEubBwLHoV00eSRef0d7RY6p7N+38ZnXUiPoVuqktGot/CApk96Jy mkcd9MflN/bd4aJpaHOyZrzKqFPxkUSgtFeghcahGyjw1M4LGoXeflS5xTbaaMroQ3lN TDdNlHzCw9doNfMqYFNpEN+WF6Q8tEWDbjhFSHNaJRFseTWy9ZNqsOe1xYRvqprN7XWn oaXxe0JlYPbYRI/LrFIdnf60TDci+s8NR28f2bWdctusrv2FqThGA2JB0SFqFGVL9us2 jnJA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1683254155; x=1685846155; h=in-reply-to:references:to:from:subject:cc:message-id:date :content-transfer-encoding:mime-version:x-gm-message-state:from:to :cc:subject:date:message-id:reply-to; bh=evsRyVdUpm9tZ3zbpYtyLZiIFPAu7MWLlo8c04t+4vY=; b=RNtuerpmRsI74eonb1q67kUz6E0DitidZ6zdrjP60f0aDUESJpuFXhsQmErhpJ2AJP 9COnoJBnUXMGkMC3w92WhrvIF9MW+zAZ6lc/CIp6Vglg5OtBXRqk1HQILIK6bmvBcqMW 2lnow6aSWioM9cl6PfeWrJYKL5b+dxhXaPw1wF0xZIL8H9WP95vxKDAokRpRZmTZ/QOb buX424ObXy6FC945neBvBRtRTxjFEilRWgEnYjOH6IRu7dP3xkRVA34dacoP2jbH/88i +9itwkjagTkmZpwtdqWOes2/+ufFnmv0xO7jx2FU4XLfGBwMJaPcQYlFVRpIjaWlCcrI 3BUg== X-Gm-Message-State: AC+VfDxr8vNeLofr/wM5QTjIeLYq/ogHJUfNxHBeqlsuXpUy3NSHxqOZ B4j34WlvKYyRc2btTtaa2zk= X-Google-Smtp-Source: ACHHUZ7SP5ujyT52IJy91MGux44+fALAl/Za+uzONf57QZ4t+E/ySlwSCIJZv2DqIpZSwxLv82pD9g== X-Received: by 2002:a05:6a21:999a:b0:fc:8dfb:3195 with SMTP id ve26-20020a056a21999a00b000fc8dfb3195mr5404412pzb.23.1683254154649; Thu, 04 May 2023 19:35:54 -0700 (PDT) Received: from localhost ([203.59.190.92]) by smtp.gmail.com with ESMTPSA id g18-20020a62e312000000b0062dd9a8c1b8sm407591pfh.100.2023.05.04.19.35.42 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 04 May 2023 19:35:53 -0700 (PDT) Mime-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=UTF-8 Date: Fri, 05 May 2023 12:35:39 +1000 Message-Id: Cc: "Sumit Garg" , "Mark Rutland" , "Matthias Kaehlcke" , "Stephane Eranian" , "Stephen Boyd" , , "Tzung-Bi Shih" , "Lecopzer Chen" , , "Masayoshi Mizuma" , "Guenter Roeck" , "Pingfan Liu" , "Andi Kleen" , "Ian Rogers" , , , , "Randy Dunlap" , "Chen-Yu Tsai" , , , , , "Will Deacon" , , , "Marc Zyngier" , "Catalin Marinas" , "Daniel Thompson" , "Colin Cross" Subject: Re: [PATCH v4 13/17] watchdog/hardlockup: detect hard lockups using secondary (buddy) CPUs From: "Nicholas Piggin" To: "Douglas Anderson" , "Petr Mladek" , "Andrew Morton" X-Mailer: aerc 0.14.0 References: <20230504221349.1535669-1-dianders@chromium.org> <20230504151100.v4.13.I6bf789d21d0c3d75d382e7e51a804a7a51315f2c@changeid> In-Reply-To: <20230504151100.v4.13.I6bf789d21d0c3d75d382e7e51a804a7a51315f2c@changeid> Precedence: bulk List-ID: X-Mailing-List: linux-perf-users@vger.kernel.org On Fri May 5, 2023 at 8:13 AM AEST, Douglas Anderson wrote: > From: Colin Cross > > Implement a hardlockup detector that doesn't doesn't need any extra > arch-specific support code to detect lockups. Instead of using > something arch-specific we will use the buddy system, where each CPU > watches out for another one. Specifically, each CPU will use its > softlockup hrtimer to check that the next CPU is processing hrtimer > interrupts by verifying that a counter is increasing. Powerpc's watchdog has an SMP checker, did you see it? It's all to all rather than buddy which makes it more complicated but arguably bit better functionality. Thanks, Nick