Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752616AbYHIROS (ORCPT ); Sat, 9 Aug 2008 13:14:18 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1750874AbYHIROE (ORCPT ); Sat, 9 Aug 2008 13:14:04 -0400 Received: from rv-out-0506.google.com ([209.85.198.236]:12717 "EHLO rv-out-0506.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750707AbYHIROB (ORCPT ); Sat, 9 Aug 2008 13:14:01 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=message-id:date:from:to:subject:cc:in-reply-to:mime-version :content-type:content-transfer-encoding:content-disposition :references; b=LmKw36Cd1+VK6B1Y/z8X8A03zyS+9lGaTthl5IS4FfIkwRJQRCWXr6ypRzZwBrEof4 5YEbwJapV2t/mEmupIGZkaYSZdy8kHMsHNW+946BP+J0pWfUD324Pb3F318rP44AZTx1 VYIJhWFKdeu/ENEmB2tGIGc6+4yOxYfrszUA0= Message-ID: <863e9df20808091014w11896139q77850bc6eb7609b3@mail.gmail.com> Date: Sat, 9 Aug 2008 22:44:01 +0530 From: "Abhishek Sagar" To: "Steven Rostedt" Subject: Re: [PATCH 0/5] ftrace: to kill a daemon Cc: linux-kernel@vger.kernel.org, "Ingo Molnar" , "Thomas Gleixner" , "Peter Zijlstra" , "Andrew Morton" , "Linus Torvalds" , "David Miller" , "Mathieu Desnoyers" , "Roland McGrath" , "Ulrich Drepper" , "Rusty Russell" , "Jeremy Fitzhardinge" , "Gregory Haskins" , "Arnaldo Carvalho de Melo" , "Luis Claudio R. Goncalves" , "Clark Williams" In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Content-Disposition: inline References: <20080807182013.984175558@goodmis.org> <863e9df20808090248h3adc2ac3mdb3217fe2876ab3b@mail.gmail.com> <863e9df20808090801p7f9e11bar84d0e661440d591e@mail.gmail.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1559 Lines: 37 On Sat, Aug 9, 2008 at 9:07 PM, Steven Rostedt wrote: > One of the things I tried to do was to make ftrace port easily to all > archs. David Miller ported it to Sparc64 in 20 minutes and that was mostly > compiling. Doing a kprobe fix would require much more knowledge to each > arch and more prone to errors. I agree with the point about porting. My kprobe reference was simply to point out that an existing module seems to be overwriting code on the fly and doesn't take care of much on non-x86 archs. Ftrace has a unique 5-byte call replacement issue specific to x86 which kprobes doesn't have to deal with. >> This solution indeed would fit all archs well but for some it may be >> an overkill (or is it?...I'd like to know that :-\ ). > > It is not an issue at all. The mcount list is discarded with the init > section, and the change to nops is relatively fast. We do make a list of > all entries anyway, so that we can pick and choose which functions we want > to enable tracing on. Ok. > I want ftrace_record_ip to be as fast as possible, and also having it call > the registered function means we need to test if it was set in the filter > too. This is too much for what record_ip does. And as I said, doing it all > on boot up would be best. Alrighty. Thanks, Abhishek Sagar -- 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/