From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 31709 invoked by alias); 25 Nov 2009 16:26:12 -0000 Received: (qmail 31672 invoked by uid 22791); 25 Nov 2009 16:26:11 -0000 X-SWARE-Spam-Status: No, hits=-2.3 required=5.0 tests=AWL,BAYES_00,SPF_HELO_PASS,SPF_PASS X-Spam-Check-By: sourceware.org Received: from mx3.mail.elte.hu (HELO mx3.mail.elte.hu) (157.181.1.138) by sourceware.org (qpsmtpd/0.43rc1) with ESMTP; Wed, 25 Nov 2009 16:26:06 +0000 Received: from elvis.elte.hu ([157.181.1.14]) by mx3.mail.elte.hu with esmtp (Exim) id 1NDKgs-000582-7x from ; Wed, 25 Nov 2009 17:26:03 +0100 Received: by elvis.elte.hu (Postfix, from userid 1004) id 16C333E22E1; Wed, 25 Nov 2009 17:25:55 +0100 (CET) Date: Wed, 25 Nov 2009 16:26:00 -0000 From: Ingo Molnar To: Thomas Gleixner Cc: Jakub Jelinek , Andrew Haley , "H.J. Lu" , rostedt@goodmis.org, "H. Peter Anvin" , LKML , Andrew Morton , Heiko Carstens , feng.tang@intel.com, Peter Zijlstra , Frederic Weisbecker , David Daney , Richard Guenther , gcc , Linus Torvalds Subject: Re: [PATCH][GIT PULL][v2.6.32] tracing/x86: Add check to detect GCC messing with mcount prologue Message-ID: <20091125162556.GA14233@elte.hu> References: <4B06EF6F.2050507@redhat.com> <6dc9ffc80911220138y15bfa91agccf5c29f1c30e09a@mail.gmail.com> <4B0972C9.302@redhat.com> <6dc9ffc80911221530t38d83cf6je739743c8d756667@mail.gmail.com> <4B0BF119.4070704@redhat.com> <20091124150604.GJ22813@hs20-bc2-1.build.redhat.com> <20091125154452.GA9456@elte.hu> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.20 (2009-08-17) Received-SPF: neutral (mx3: 157.181.1.14 is neither permitted nor denied by domain of elte.hu) client-ip=157.181.1.14; envelope-from=mingo@elte.hu; helo=elvis.elte.hu; X-ELTE-SpamScore: -2.0 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-2.0 required=5.9 tests=BAYES_00 autolearn=no SpamAssassin version=3.2.5 -2.0 BAYES_00 BODY: Bayesian spam probability is 0 to 1% [score: 0.0000] X-IsSubscribed: yes Mailing-List: contact gcc-help@gcc.gnu.org; run by ezmlm Precedence: bulk List-Id: List-Archive: List-Post: List-Help: Sender: gcc-owner@gcc.gnu.org X-SW-Source: 2009-11/txt/msg00675.txt.bz2 * Thomas Gleixner wrote: > On Wed, 25 Nov 2009, Ingo Molnar wrote: > > * Thomas Gleixner wrote: > > > > > On Tue, 24 Nov 2009, Jakub Jelinek wrote: > > > > > > > On Tue, Nov 24, 2009 at 03:55:49PM +0100, Thomas Gleixner wrote: > > > > > > you should compile your code with -maccumulate-outgoing-args, and there's > > > > > > no need to use -mtune=generic. Is that right? > > > > > > > > > > Seems to work. What other side effects has that ? > > > > > > > > Faster code, significant increase in code size though. Note that on many > > > > architectures it is the only supported model. > > > > > > Just checked on the affected -marchs. The increase in code size is > > > about 3% which is not that bad and definitely acceptable for the > > > tracing case. Will zap the -mtune=generic patch and use > > > -maccumulate-outgoing-args instead. > > > > hm, 3% sounds quite large :( dyn-ftrace is enabled in distro configs, so > > 3% is a big deal IMO. > > Distro-configs have -mtune=generic anyway. So it's not changing > anything for them. > > I'm talking about the -march flags which result in that weird code > (pentium-mmx ....). ok! Ingo