Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756769AbZJVVzQ (ORCPT ); Thu, 22 Oct 2009 17:55:16 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755956AbZJVVzQ (ORCPT ); Thu, 22 Oct 2009 17:55:16 -0400 Received: from hrndva-omtalb.mail.rr.com ([71.74.56.122]:53696 "EHLO hrndva-omtalb.mail.rr.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755639AbZJVVzP (ORCPT ); Thu, 22 Oct 2009 17:55:15 -0400 Subject: Re: [PATCH -v4 4/9] tracing: add static function tracer support for MIPS From: Steven Rostedt Reply-To: rostedt@goodmis.org To: Adam Nemet Cc: David Daney , wuzhangjin@gmail.com, Richard Sandiford , linux-kernel@vger.kernel.org, linux-mips@linux-mips.org, Thomas Gleixner , Ralf Baechle , Nicholas Mc Guire In-Reply-To: <19168.52948.22223.757259@ropi.home> 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> Content-Type: text/plain Organization: Kihon Technologies Inc. Date: Thu, 22 Oct 2009 17:55:17 -0400 Message-Id: <1256248517.20866.806.camel@gandalf.stny.rr.com> Mime-Version: 1.0 X-Mailer: Evolution 2.26.3 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1092 Lines: 30 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. -- Steve -- 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/