From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753150AbcHOQ5R (ORCPT ); Mon, 15 Aug 2016 12:57:17 -0400 Received: from mail-db5eur01on0045.outbound.protection.outlook.com ([104.47.2.45]:43664 "EHLO EUR01-DB5-obe.outbound.protection.outlook.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1752859AbcHOQ5P (ORCPT ); Mon, 15 Aug 2016 12:57:15 -0400 Authentication-Results: spf=none (sender IP is ) smtp.mailfrom=cmetcalf@mellanox.com; Subject: Re: [PATCH v7 4/4] nmi_backtrace: generate one-line reports for idle cpus To: Petr Mladek References: <1470672218-16059-1-git-send-email-cmetcalf@mellanox.com> <1470672218-16059-5-git-send-email-cmetcalf@mellanox.com> <20160809124325.GG13300@pathway.suse.cz> <20160811152538.GH13300@pathway.suse.cz> CC: Peter Zijlstra , "Rafael J. Wysocki" , Russell King , Thomas Gleixner , Aaron Tomlin , Ingo Molnar , Andrew Morton , Daniel Thompson , , , , From: Chris Metcalf Message-ID: <12bc082c-067b-2b85-6c17-ff0a6c011add@mellanox.com> Date: Mon, 15 Aug 2016 12:41:54 -0400 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:45.0) Gecko/20100101 Thunderbird/45.2.0 MIME-Version: 1.0 In-Reply-To: <20160811152538.GH13300@pathway.suse.cz> Content-Type: text/plain; charset="windows-1252"; format=flowed Content-Transfer-Encoding: 7bit X-Originating-IP: [12.216.194.146] X-ClientProxiedBy: CY1PR1201CA0032.namprd12.prod.outlook.com (10.169.17.170) To AM4PR0501MB2755.eurprd05.prod.outlook.com (10.172.216.11) X-MS-Office365-Filtering-Correlation-Id: 64572a0b-77b4-44c7-8542-08d3c52b19ae X-Microsoft-Exchange-Diagnostics: 1;AM4PR0501MB2755;2:Be8+pCGc0ARJ0PYzIompNT2kG4CikAnBfJou+I7v+tx6KL+9YK89CeAi5G8Z7QLZw+yn9eY/bGMhGZ5sD2Y79xXyvvcHYeyFdkyLlHoiWnXRqp2gprk4VhgrINvcojPP/E/KjlHKxDUWJW05W6wZNPahAhnojY3b5viZ1fqWX2XBgjfFmi3ZTmcXUNtFL3aV;3:fgNlFndDwnhPcxf5d97LoMmOh14zRwmlDqNmkpD73HZ1hd3ajI02j6F0NnDqqZDampOzIeNSh9AGGX9PrB4y2zt9678DULvkO1QLPDJKRZQWHZ6SuiX0LyAZCbDdgcQK X-Microsoft-Antispam: UriScan:;BCL:0;PCL:0;RULEID:;SRVR:AM4PR0501MB2755; 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Suppress >>>> messages for cpus that are idling when they are interrupted and just >>>> emit one line, "NMI backtrace for N skipped: idling at pc 0xNNN". > Hmm, the problem is that native_safe_halt() is called from default_idle() > here. The function is marked as inline but the compiler did not inline > it. > > It helped me to put native_safe_halt() into the __cpuidle_text section: Following Peter Z's suggestion, I have added an __always_inline marker to native_safe_halt. For consistency, I also did arch_safe_halt(), since that invokes native_safe_halt, and then also native_halt() and halt(), so that we're not being weirdly inconsistent with markings for halt inlines. There are also the native_irq_enable(), etc., accessors in that same header that are still only marked "inline" not "always_inline", but I wanted to stop before I was touching too much unrelated code. > I wonder if it would be possible to detect the idle thread an other > way. For example, I wonder if it would be enough to check for the > PID 0. No, the problem is that pid 0 can also go off and run "interesting" code for things like power management, etc., so we really just want to focus on being quite sure that the running code isn't interesting before we suppress the backtrace information. See the thread around here: https://lkml.kernel.org/r/20160307204317.GR6344@twins.programming.kicks-ass.net -- Chris Metcalf, Mellanox Technologies http://www.mellanox.com