From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758221Ab0DPBtk (ORCPT ); Thu, 15 Apr 2010 21:49:40 -0400 Received: from mail-wy0-f174.google.com ([74.125.82.174]:49629 "EHLO mail-wy0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758188Ab0DPBtj (ORCPT ); Thu, 15 Apr 2010 21:49:39 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=date:from:to:cc:subject:message-id:references:mime-version :content-type:content-disposition:in-reply-to:user-agent; b=JA/IIhxmX6Mzck4ey37fGMBpUSTGMrLPmWcb69zJAWFOtQdJAdqIqCD1cW2P2y8dKp WikU+/xtwUEV8YLrG5fDsEeNjzpKWpWu78q4OA0MWpaFUSwG4sgystlNetpgBW1AZK9+ tKgdKLAGqDdiRVt/ZuHZmJ1filXTy7AlBO+Eo= Date: Fri, 16 Apr 2010 03:49:38 +0200 From: Frederic Weisbecker To: Thomas Gleixner Cc: Chase Douglas , linux-kernel@vger.kernel.org, Steven Rostedt , Ingo Molnar , Randy Dunlap Subject: Re: [PATCH 3/3] Stop tracing on a schedule bug Message-ID: <20100416014937.GD15570@nowhere> References: <1271262016-18650-1-git-send-email-chase.douglas@canonical.com> <1271262016-18650-3-git-send-email-chase.douglas@canonical.com> <20100415210357.GG5069@nowhere> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Apr 16, 2010 at 02:21:47AM +0200, Thomas Gleixner wrote: > On Fri, 16 Apr 2010, Thomas Gleixner wrote: > > BTW, if interacting with grub is that hard: how does an user start the > > tracer at all ? > > Just looked through the other patches and noticed that the patch which > provides the tracing_off(level) stuff is incomplete as it provides > only a command line option to change that tracing off level. > > The command line option is merily for tracing which happens to be > started on the command line i.e. _BEFORE_ we have usable user space. > > So your grub argument is just crap. If the user cannot change this > setting w/o fiddling with the obscured grub then he can not start the > tracer on the command line either. > > But somehow he can start the tracer later when user space is up and > running, but there is no way to change that setting anymore. Therefor > you go through the kernel and impose settings at will. > > 1) Your patch simply lacks an interface to change that setting via > debugfs/tracing/wtf > > WTF should I reboot my machine to change that setting from the > default BUG to WARN or NONE ? There is no reason at all. > > 2) tracing off can be done via filters on functions and/or events > already - so I doubt that the tracing_off_event(level) is necessary > at all. Yeah it works for the function tracer, but not for events (or other tracers), or I missed this feature somehow.