Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759154AbZANUwJ (ORCPT ); Wed, 14 Jan 2009 15:52:09 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753790AbZANUvv (ORCPT ); Wed, 14 Jan 2009 15:51:51 -0500 Received: from mx3.mail.elte.hu ([157.181.1.138]:36062 "EHLO mx3.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751108AbZANUvu (ORCPT ); Wed, 14 Jan 2009 15:51:50 -0500 Date: Wed, 14 Jan 2009 21:51:22 +0100 From: Ingo Molnar To: Andrew Morton Cc: torvalds@linux-foundation.org, a.p.zijlstra@chello.nl, paulmck@linux.vnet.ibm.com, ghaskins@novell.com, matthew@wil.cx, andi@firstfloor.org, chris.mason@oracle.com, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-btrfs@vger.kernel.org, tglx@linutronix.de, npiggin@suse.de, pmorreale@novell.com, SDietrich@novell.com, dmitry.adamushko@gmail.com, hannes@cmpxchg.org Subject: Re: [GIT PULL] adaptive spinning mutexes Message-ID: <20090114205122.GC6519@elte.hu> References: <1231864854.7141.8.camel@twins> <1231867314.7141.16.camel@twins> <1231952436.14825.28.camel@laptop> <20090114183319.GA18630@elte.hu> <20090114105300.66bd014d.akpm@linux-foundation.org> <20090114190008.GA13203@elte.hu> <20090114113638.c818fcf8.akpm@linux-foundation.org> <20090114201435.GA6519@elte.hu> <20090114123017.9acf42d7.akpm@linux-foundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20090114123017.9acf42d7.akpm@linux-foundation.org> User-Agent: Mutt/1.5.18 (2008-05-17) X-ELTE-VirusStatus: clean X-ELTE-SpamScore: -1.5 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-1.5 required=5.9 tests=BAYES_00 autolearn=no SpamAssassin version=3.2.3 -1.5 BAYES_00 BODY: Bayesian spam probability is 0 to 1% [score: 0.0000] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1654 Lines: 51 * Andrew Morton wrote: > > > Do people enable CONFIG_SCHED_DEBUG? > > > > If they suspect performance problems and want to analyze them? > > The vast majority of users do not and usually cannot compile their own > kernels. ... which they derive from distro kernels or some old .config they always used, via 'make oldconfig'. You are arguing against well-established facts here. If you dont believe my word for it, here's an analysis of all kernel configs posted to lkml in the past 8 months: $ grep ^CONFIG_SCHED_DEBUG linux-kernel | wc -l 424 $ grep 'CONFIG_SCHED_DEBUG is not' linux-kernel | wc -l 109 i.e. CONFIG_SCHED_DEBUG=y is set in 80% of the configs. A large majority of testers has it enabled and /sys/debug/sched_features was always a good mechanism that we used for runtime toggles. > > Note that CONFIG_SCHED_DEBUG=y is also the default. > > akpm:/usr/src/25> echo $ARCH > x86_64 > akpm:/usr/src/25> make defconfig > *** Default configuration is based on 'x86_64_defconfig' x86 defconfig is used too, but it's a pretty rare usage. Under default i mean the customary meaning of default config: it's the default if you come via 'make oldconfig' or if you derive your config from a distro config: | config SCHED_DEBUG | bool "Collect scheduler debugging info" | depends on DEBUG_KERNEL && PROC_FS | default y Ingo -- 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/