Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760112Ab3ICN2g (ORCPT ); Tue, 3 Sep 2013 09:28:36 -0400 Received: from fold.natur.cuni.cz ([195.113.57.32]:41569 "EHLO fold.natur.cuni.cz" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759956Ab3ICN2f (ORCPT ); Tue, 3 Sep 2013 09:28:35 -0400 Message-ID: <5225E3DB.5070507@gmail.com> Date: Tue, 03 Sep 2013 15:27:55 +0200 From: =?UTF-8?B?TWFydGluIE1PS1JFSsWg?= User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:23.0) Gecko/20100101 Firefox/23.0 SeaMonkey/2.20 MIME-Version: 1.0 To: Catalin Marinas CC: Max Filippov , LKML Subject: Re: 3.10.9: kmemleak disables all CPUs except CPU0 References: <5221F119.4070000@gmail.com> <20130902154840.GC13871@arm.com> <5224B3F5.8090402@gmail.com> <20130902160908.GE13871@arm.com> In-Reply-To: <20130902160908.GE13871@arm.com> X-Enigmail-Version: 1.5.2 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2347 Lines: 59 Catalin Marinas wrote: > On Mon, Sep 02, 2013 at 04:51:17PM +0100, Martin MOKREJŠ wrote: >> Catalin Marinas wrote: >>> On Mon, Sep 02, 2013 at 04:44:52PM +0100, Max Filippov wrote: >>>> On Mon, Sep 2, 2013 at 7:31 PM, Catalin Marinas wrote: >>>>> On 31 August 2013 14:35, Martin MOKREJŠ wrote: >>>>>> never realized that my CPUs are gone if I compile into kernel kmemleak. >>>>>> Is that really the aim? >>>>>> >>>>>> CONFIG_HAVE_DEBUG_KMEMLEAK=y >>>>>> CONFIG_DEBUG_KMEMLEAK=y >>>>>> CONFIG_DEBUG_KMEMLEAK_EARLY_LOG_SIZE=400 >>>>>> # CONFIG_DEBUG_KMEMLEAK_TEST is not set >>>>>> # CONFIG_DEBUG_KMEMLEAK_DEFAULT_OFF is not set >>>>>> >>>>>> 1. Why isn't there /sys/devices/system/cpu/cpu0/online file? >>>>>> Does not matter if it contains 0 or 1. It just should exist. >>>>> >>>>> I can't really see how kmemleak would do this, maybe other config >>>>> options that get set/cleared in the process of selecting kmemleak. Can >>>> >>>> Seems to be kmemcheck: from arch/x86/mm/kmemcheck/kmemcheck.c: >>>> >>>> int __init kmemcheck_init(void) >>>> { >>>> #ifdef CONFIG_SMP >>>> /* >>>> * Limit SMP to use a single CPU. We rely on the fact that this code >>>> * runs before SMP is set up. >>>> */ >>>> if (setup_max_cpus > 1) { >>>> printk(KERN_INFO >>>> "kmemcheck: Limiting number of CPUs to 1.\n"); >>>> setup_max_cpus = 1; >>>> } >>>> #endif >>> >>> Ah, ok, not my problem then ;) >> >> Fine, so would somebody please update the help text accessible in "menuconfig" >> for this entry? It should be clear that it has a huge performance impact if enabled. >> And, by compiling in it is enabled by default. > > Otherwise, of no-one volunteers, please feel free to send a patch ;) No, I am not a kernel developer. Please someone else do so update the "help text". Moreover, it does not explain why /sys/devices/system/cpu/cpu0/online file is missing while /sys/devices/system/cpu/cpu[1-3]/online do exist at the same time. Thank you, Martin -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/