From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754537AbYITOhi (ORCPT ); Sat, 20 Sep 2008 10:37:38 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751319AbYITOha (ORCPT ); Sat, 20 Sep 2008 10:37:30 -0400 Received: from hrndva-omtalb.mail.rr.com ([71.74.56.122]:55171 "EHLO hrndva-omtalb.mail.rr.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751289AbYITOh3 (ORCPT ); Sat, 20 Sep 2008 10:37:29 -0400 Date: Sat, 20 Sep 2008 10:37:28 -0400 (EDT) From: Steven Rostedt X-X-Sender: rostedt@gandalf.stny.rr.com To: Sitsofe Wheeler cc: Peter Zijlstra , Ingo Molnar , Arjan van de Ven , LKML , lenb@kernel.org, astarikovskiy@suse.de Subject: Re: Reading EeePC900 battery info causes stalls (was Re: How how latent should non-preemptive scheduling be?) In-Reply-To: <48D50498.5050608@yahoo.com> Message-ID: References: <48D4CC1B.7030708@yahoo.com> <48D50498.5050608@yahoo.com> User-Agent: Alpine 1.10 (DEB 962 2008-03-14) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, 20 Sep 2008, Sitsofe Wheeler wrote: > Steven Rostedt wrote: > > The wake up tracing is CONFIG_SCHED_TRACER. If you do not see "wakeup" as > > one of the available tracers in available_tracers, then check > > your dmesg and see if you have CONFIG_FTRACE_STARTUP_TEST enabled. There was > > a known bug that would cause the wakeup tracing to fail the test. When a > > trace fails the startup test, it is disabled. > > This is exactly the case (dmesg reports the ftrace wakeup startup test > failed). That's what I get for not reading my dmesg more carefully... OK, that is probably the known bug you are hitting. Simply disable the CONFIG_FTRACE_STARTUP_TEST and you should have the wakeup tracer. The bug is with the test, not the tracer, so it should not hurt you. -- Steve