From: Theodore Tso Subject: Re: [ltt-dev] Fw: [PATCH] ext4: Add markers for better debuggability Date: Fri, 9 Jan 2009 13:58:40 -0500 Message-ID: <20090109185840.GD23869@mit.edu> References: <20090109170408.75C1.KOSAKI.MOTOHIRO@jp.fujitsu.com> <20090109144901.GA7262@Krystal> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: KOSAKI Motohiro , ltt-dev@lists.casi.polymtl.ca, Ext4 Developers List To: Mathieu Desnoyers Return-path: Received: from thunk.org ([69.25.196.29]:33274 "EHLO thunker.thunk.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753097AbZAIS6p (ORCPT ); Fri, 9 Jan 2009 13:58:45 -0500 Content-Disposition: inline In-Reply-To: <20090109144901.GA7262@Krystal> Sender: linux-ext4-owner@vger.kernel.org List-ID: On Fri, Jan 09, 2009 at 09:49:01AM -0500, Mathieu Desnoyers wrote: > > Given this is meant to be in the mainline kernel, using tracepoints > rather than markers would be more appropriate. Please see > Documentation/tracepoints.txt and samples/tracepoints/ for details. I saw that, but I'm still not sure how I would actually *use* tracepoints. I can use markers today with Systemtap, and I need an easy way to be able to selectively do things like "trap and print all of the logged data when the ext4_request_inode tracepoint/marker is tripped where dev=='dm-8'". Unfortunately, Systemtap seems doomed given its current course and direction, so I'm not opposed to moving to another solution --- I just need a HOWTO that demonstrates how I can do this painlessly and easily; preferably without having me have to manually hack up a kernel module each time I want to implement the tracing Is there an easy way to do that using ltt today? Can you point me at a sample of how this could be done? - Ted