From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754201AbZFUKph (ORCPT ); Sun, 21 Jun 2009 06:45:37 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752469AbZFUKpa (ORCPT ); Sun, 21 Jun 2009 06:45:30 -0400 Received: from mx3.mail.elte.hu ([157.181.1.138]:59747 "EHLO mx3.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752088AbZFUKpa (ORCPT ); Sun, 21 Jun 2009 06:45:30 -0400 Date: Sun, 21 Jun 2009 12:45:27 +0200 From: Ingo Molnar To: Steven Rostedt Cc: linux-kernel@vger.kernel.org, Andrew Morton , Frederic Weisbecker Subject: Re: [PATCH 1/2] function-graph: disable when both x86_32 and optimize for size are configured Message-ID: <20090621104527.GA22961@elte.hu> References: <20090618224409.916725341@goodmis.org> <20090618225248.476090968@goodmis.org> <20090620162513.GD32377@elte.hu> 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) 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=3.2.5 -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 * Steven Rostedt wrote: > On Sat, 20 Jun 2009, Ingo Molnar wrote: > > > > > * Steven Rostedt wrote: > > > > > diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig > > > index 4a13e5a..1eac852 100644 > > > --- a/kernel/trace/Kconfig > > > +++ b/kernel/trace/Kconfig > > > @@ -121,6 +121,7 @@ config FUNCTION_GRAPH_TRACER > > > bool "Kernel Function Graph Tracer" > > > depends on HAVE_FUNCTION_GRAPH_TRACER > > > depends on FUNCTION_TRACER > > > + depends on !X86_32 || !CC_OPTIMIZE_FOR_SIZE > > > default y > > > > Hm, nice fix, but this is a quite nasty constraint - distros like to > > enable CC_OPTIMIZE_FOR_SIZE as it neatly trims the kernel's size by > > about 30%. > > > > Just in case you have not checked yet: is there no way to turn off > > the specific gcc optimization that causes this? Or is it -Os itself > > that does this optimization? > > It seems to me that -Os causes it for i386. I did a make V=1 to > capture how the files in question were being compiled, and tried > various disabling of flags. -Os was the only one to make a > difference. :-( oh well. I think GCC should be fixed/improved to not do this particular (rather narrow looking) optimization if -pg is specified too. Ingo