From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751114AbWISU2H (ORCPT ); Tue, 19 Sep 2006 16:28:07 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751119AbWISU2H (ORCPT ); Tue, 19 Sep 2006 16:28:07 -0400 Received: from tomts5.bellnexxia.net ([209.226.175.25]:22518 "EHLO tomts5-srv.bellnexxia.net") by vger.kernel.org with ESMTP id S1751114AbWISU2E (ORCPT ); Tue, 19 Sep 2006 16:28:04 -0400 Date: Tue, 19 Sep 2006 16:28:02 -0400 From: Mathieu Desnoyers To: "Frank Ch. Eigler" Cc: linux-kernel@vger.kernel.org, Christoph Hellwig , Andrew Morton , Ingo Molnar , Greg Kroah-Hartman , Thomas Gleixner , Douglas Niehaus , Tom Zanussi , Paul Mundt , Jes Sorensen , Richard J Moore , William Cohen , "Martin J. Bligh" , Michel Dagenais , systemtap@sources.redhat.com, ltt-dev@shafik.org Subject: Re: [PATCH] Linux Kernel Markers 0.2 for Linux 2.6.17 Message-ID: <20060919202802.GB552@Krystal> References: <20060919183447.GA16095@Krystal> <20060919193623.GA9459@Krystal> <20060919194515.GB18646@redhat.com> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="=_Krystal-9150-1158697682-0001-2" Content-Disposition: inline In-Reply-To: <20060919194515.GB18646@redhat.com> X-Editor: vi X-Info: http://krystal.dyndns.org:8080 X-Operating-System: Linux/2.4.32-grsec (i686) X-Uptime: 16:19:19 up 27 days, 17:28, 6 users, load average: 0.55, 0.40, 0.37 User-Agent: Mutt/1.5.13 (2006-08-11) Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org This is a MIME-formatted message. If you see this text it means that your E-mail software does not support MIME-formatted messages. --=_Krystal-9150-1158697682-0001-2 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable * Frank Ch. Eigler (fche@redhat.com) wrote: > Hi - >=20 > On Tue, Sep 19, 2006 at 03:36:24PM -0400, Mathieu Desnoyers wrote: > > [...] > > > If you don't allow yourself to presume on-the-fly function > > > recompilation, then these markers would need to be made run-time > > > rather than compile-time configurable. That is, not like this: > > > [...] >=20 > > By making them run-time configurable, I don't see any whay not to bloat= the > > kernel. How can be embed calls to printk+function+kprobe+djprobe without > > having some kind of performance impact ? >=20 > In order to have what we appear to need, we cannot avoid having some > impact. (Even NOPs have impact.) >=20 I am all for giving this decision to the end-user or the distribution which= will configure the kernel. There is no "perfect" or "for all" solution that I am aware of. * Users debugging servers will more likely want the kprobe or jprobe option. * Users interested in high performance tracing will want fprobe and/or jpro= be. * Users interested in embedded systems will want to avoid tools outside the kernel that rely on module loading : their kernel often not even support modules. -> fprobe > Suppose that mbligh's clever but speculative idea has some nasty flaw, > once someone tried to reduce it to code. Do you see that markers > along the lines you've posted would be unsatisfactory? With that in > mind, is there point adding such markers now? >=20 M. Bligh's idea is an interesting use of fprobes through modules that could= make dynamic tracing more effective for accessing local variables. It does not change anything to the various needs of the above-mentioned class of users, except that it may make life of high performance and server users easier. W= ith or without his idea, the goal of this marker mechanism is to meet all those user's different needs. Mathieu OpenPGP public key: http://krystal.dyndns.org:8080/key/compudj= =2Egpg Key fingerprint: 8CD5 52C3 8E3C 4140 715F BA06 3F25 A8FE 3BAE 9A68=20 --=_Krystal-9150-1158697682-0001-2 Content-Type: application/pgp-signature; name="signature.asc" Content-Transfer-Encoding: 7bit Content-Description: Digital signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.5 (GNU/Linux) iD8DBQFFEFLSPyWo/juummgRAjSWAJ0SRMVFnjSG2pwnx0JXC54OTC3OMgCgpFoT xXm3Gli0Fh5f5Vb1OOB9ILs= =IsJ6 -----END PGP SIGNATURE----- --=_Krystal-9150-1158697682-0001-2--