From: "Frank Ch. Eigler" Subject: Re: [RFC][PATCH 0/5] NFS: trace points added to mounting path Date: Mon, 19 Jan 2009 10:41:33 -0500 Message-ID: <20090119154133.GE1574@redhat.com> References: <4970B451.4080201@RedHat.com> <49711BDF.3010605@melbourne.sgi.com> <4973B777.2000102@melbourne.sgi.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Steve Dickson , NFS list , SystemTAP , Linux NFSv4 mailing list To: Greg Banks Return-path: Received: from mx2.redhat.com ([66.187.237.31]:43193 "EHLO mx2.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751843AbZASPll (ORCPT ); Mon, 19 Jan 2009 10:41:41 -0500 In-Reply-To: <4973B777.2000102-cP1dWloDopni96+mSzHFpQC/G2K4zDHf@public.gmane.org> Sender: linux-nfs-owner@vger.kernel.org List-ID: Hi - On Mon, Jan 19, 2009 at 10:12:55AM +1100, Greg Banks wrote: > [...] > > It would make more sense to me to turn dprintk's into trace_marks, > Umm, ok. Sorry to be so ignorant but where would I find the doc that > tells me about adding trace marks ? Documentation/markers.txt > The control interface seems a little primitive. It seems like you > can only activate and deactivate single printks ? Or single classes (identical names) per activate/deactivate call. > I don't see a way to e.g. activate every trace make in a particular > function, or in a particular .c file. I thought both of these were > useful things to do, so I implemented them. Below is an extract > from the doc that accompanies the sgi-dprintk module. [...] Very clever! I am not an insider enough to carry much weight in this regard, but it would make most sense to me if the sgi-dprintk widget were adapted so that: - it used trace_mark() as the low-level hook mechanism at the call sites - it extended the trace_mark structures to track __FILE__/__LINE__/__FUNCTION__ values - it extended the marker activation API to be able to specify queries based upon those __FILE__/etc. fields - as an extension to the proposed marker->ftrace patch, extend the option parser the same way as your /proc/dprintk does The benefits might not be huge, but: - it would reuse existing functionality (markers for the hooks, other ftrace widgets for extra info to gather at each event - like the stack traces) - it could generalize the handling of these dprintks, by not just being tied to message printing, but becoming of possible use for statistics/health monitoring - FChE