Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751891AbZJWBJV (ORCPT ); Thu, 22 Oct 2009 21:09:21 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751731AbZJWBJV (ORCPT ); Thu, 22 Oct 2009 21:09:21 -0400 Received: from qw-out-2122.google.com ([74.125.92.26]:58953 "EHLO qw-out-2122.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751660AbZJWBJU (ORCPT ); Thu, 22 Oct 2009 21:09:20 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=subject:from:reply-to:to:cc:in-reply-to:references:content-type :organization:date:message-id:mime-version:x-mailer :content-transfer-encoding; b=ic096U9Ff+4RbliutfMdGRG5TdwQzjqfZBd/v509t+nF01hQTBFVs7VLn1WZ16C7o+ RyCoAvazgNlXn5jw/4JYgikD5lOQqCYdZTHMkeOZptS1TEX21ZN+uEW8Pi0Nh4voLCzH 6jzk1HlNMRmaM9KNo4BDq0/gwJ3dsDqBLejdE= Subject: Re: [PATCH -v4 4/9] tracing: add static function tracer support for MIPS From: Wu Zhangjin Reply-To: wuzhangjin@gmail.com To: rostedt@goodmis.org Cc: Adam Nemet , David Daney , Richard Sandiford , linux-kernel@vger.kernel.org, linux-mips@linux-mips.org, Thomas Gleixner , Ralf Baechle , Nicholas Mc Guire In-Reply-To: <1256248517.20866.806.camel@gandalf.stny.rr.com> References: <028867b99ec532b84963a35e7d552becc783cafc.1256135456.git.wuzhangjin@gmail.com> <2f73eae542c47ac5bbb9f7280e6c0271d193e90d.1256135456.git.wuzhangjin@gmail.com> <3f0d3515f74a58f4cfd11e61b62a129fdc21e3a7.1256135456.git.wuzhangjin@gmail.com> <1256138686.18347.3039.camel@gandalf.stny.rr.com> <1256233679.23653.7.camel@falcon> <4AE0A5BE.8000601@caviumnetworks.com> <19168.49354.525249.654494@ropi.home> <1256244726.20866.802.camel@gandalf.stny.rr.com> <19168.52948.22223.757259@ropi.home> <1256248517.20866.806.camel@gandalf.stny.rr.com> Content-Type: text/plain Organization: DSLab, Lanzhou University, China Date: Fri, 23 Oct 2009 09:09:06 +0800 Message-Id: <1256260146.6381.4.camel@falcon> Mime-Version: 1.0 X-Mailer: Evolution 2.26.1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1504 Lines: 45 On Thu, 2009-10-22 at 17:55 -0400, Steven Rostedt wrote: > On Thu, 2009-10-22 at 14:29 -0700, Adam Nemet wrote: > > Steven Rostedt writes: > > > On Thu, 2009-10-22 at 13:30 -0700, Adam Nemet wrote: > > > > Also note that for functions invoked via tail call you won't get an exit > > > > event. E.g. if bar is tail-called from foo: > > > > > > > > foo entered > > > > bar entered > > > > foo/bar exited > > > > > > > > However, this is not MIPS-specific and you can always disable tail calls > > > > with -fno-optimize-sibling-calls. > > > > > > The question is, would bar have a _mcount call? So far, we have not had > > > any issues with this on either x86 nor PPC. > > > > Yes, bar will have an _mcount call. The difference is that bar will return to > > foo's caller directly rather than to foo first. > > I guess the best bet is to have CONFIG_FUNCTION_GRAPH enable > -fno-optimize-sibling-calls and be done with it. > Hello, This did for us: Makefile: ifdef CONFIG_FRAME_POINTER KBUILD_CFLAGS += -fno-omit-frame-pointer -fno-optimize-sibling-calls else KBUILD_CFLAGS += -fomit-frame-pointer endif So, the only thing we need to do is enabling CONFIG_FRAME_POINTER. Seems it was selected by FTRACE by default. Regards, Wu Zhangjin -- 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/