Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756599Ab0FII7N (ORCPT ); Wed, 9 Jun 2010 04:59:13 -0400 Received: from mail-px0-f174.google.com ([209.85.212.174]:46636 "EHLO mail-px0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756423Ab0FII7G (ORCPT ); Wed, 9 Jun 2010 04:59:06 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc:content-type; b=uRg6Fymn5yBx/Z3cpXIKRVYs0XcehjpUMeH1IccQ6/vsAjlRvk08fB4MPDG+79r6Rh R/KQL9Qh+pzgIVJns3W3Gt1pAbM8Pr5zZ536lOrEaW7fVm5ZL0ArqSe2TUhSjFXwo1zR AVkRwXrZSFsIZYErNTLhZWRq6qsqTyM//eLIo= MIME-Version: 1.0 In-Reply-To: References: <1276051329.13426.48.camel@localhost.localdomain> Date: Wed, 9 Jun 2010 16:59:03 +0800 Message-ID: Subject: Re: When and how to use ftrace? From: wu zhangjin To: Ryan Wang Cc: Neependra Khare , Steven Rostedt , linux-kernel@vger.kernel.org, kernelnewbies@nl.linux.org Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2057 Lines: 60 Hi, On Wed, Jun 9, 2010 at 4:14 PM, Ryan Wang wrote: [...] >>> >>> -- >>> To unsubscribe from this list: send an email with >>> "unsubscribe kernelnewbies" to ecartis@nl.linux.org >>> Please read the FAQ at http://kernelnewbies.org/FAQ >>> >> >> > > Seems ftrace is helpful to study the activities inside the kernel to me. > I wonder whether it can be useful to debug kernel bugs. And if so, will > you please give me some examples? Yeah, did you read this paper written by Steven: "Finding Origins of Latencies Using Ftrace" (please google to download it). If not, please read it. that paper will tell you what Ftrace really is and will show the demos how to play with it. > Or so far it's mainly used for > observing the running status of kernel? Ftrace is originally created for debugging and optimizing the preempt-rt, but of course, it becomes a tracing framework currently. It not only show you what the kernel space does when you do something in user space, but will show you the calling tree of kernel functions, time consuming of every function and even allow you to filter the parts you care about. If you need more info about it, please refer to: [1] Debugging the kernel using Ftrace http://lwn.net/Articles/365835/ http://lwn.net/Articles/366796/ [2] Ftrace usage .... Documentation/trace/ftrace.txt Documentation/trace/ftrace-desgin.txt [3] Tools for Ftrace trace-cmd from readhat... Regards, -- Studying engineer. Wu Zhangjin Lanzhou University http://www.lzu.edu.cn Distributed & Embedded System Lab http://dslab.lzu.edu.cn School of Information Science and Engeneering http://xxxy.lzu.edu.cn wuzhangjin@gmail.com http://falcon.oss.lzu.edu.cn Address:Tianshui South Road 222,Lanzhou,P.R.China Zip Code:730000 Tel:+86-931-8912025 -- 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/