Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751695AbWIYXdk (ORCPT ); Mon, 25 Sep 2006 19:33:40 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751691AbWIYXdj (ORCPT ); Mon, 25 Sep 2006 19:33:39 -0400 Received: from tomts40-srv.bellnexxia.net ([209.226.175.97]:50881 "EHLO tomts40-srv.bellnexxia.net") by vger.kernel.org with ESMTP id S1751688AbWIYXdi (ORCPT ); Mon, 25 Sep 2006 19:33:38 -0400 Date: Mon, 25 Sep 2006 19:28:28 -0400 From: Mathieu Desnoyers To: "Frank Ch. Eigler" Cc: Martin Bligh , Masami Hiramatsu , prasanna@in.ibm.com, Andrew Morton , Ingo Molnar , Paul Mundt , linux-kernel , Jes Sorensen , Tom Zanussi , Richard J Moore , Michel Dagenais , Christoph Hellwig , Greg Kroah-Hartman , Thomas Gleixner , William Cohen , ltt-dev@shafik.org, systemtap@sources.redhat.com, Alan Cox , Jeremy Fitzhardinge , Karim Yaghmour , Pavel Machek , Joe Perches , "Randy.Dunlap" , "Jose R. Santos" Subject: Re: [PATCH] Linux Kernel Markers 0.11 for 2.6.17 Message-ID: <20060925232828.GA29343@Krystal> References: <20060925151028.GA14695@Krystal> <20060925160115.GE25296@redhat.com> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="=_Krystal-13748-1159226909-0001-2" Content-Disposition: inline In-Reply-To: <20060925160115.GE25296@redhat.com> X-Editor: vi X-Info: http://krystal.dyndns.org:8080 X-Operating-System: Linux/2.4.32-grsec (i686) X-Uptime: 19:19:12 up 33 days, 20:27, 6 users, load average: 0.53, 0.24, 0.16 User-Agent: Mutt/1.5.13 (2006-08-11) Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3133 Lines: 93 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-13748-1159226909-0001-2 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable Hi, * Frank Ch. Eigler (fche@redhat.com) wrote: > Hi - >=20 > > [...] > > - It _does not_ change the compiler optimisations. >=20 > Like any similar mechanism, it does force the compiler to change its > code generation, so one can't claim this too strongly. >=20 Yes, memory dependencies are changed, you are right. I was principally talk= ing about the inline and unrolled loops optimisations. > > [...] Comments are welcome, >=20 > I'm still uneasy about the use of varargs. The current code now uses > the formatting string as metadata to be matched (strcmp) between > producer and consumer. A general tool that would use them would have > to start parsing general printf directives. If you want to generate probes automatically, yes. > I believe they are not > quite general enough either e.g. to describe a raw binary blob. >=20 If you want to dump a raw binary blob, what about : MARK(mysubsys_myevent, "char %p %u", blobptr, blobsize); where %p is a pointer to an array of char and %u the length ? My idea is to use the string to identify what is referred by a pointer, so = it can be casted into this type with some kind of coherency between the marker= and the probe. > I realize they serve a useful purpose in abbreviating what otherwise > one might have to do (like that multiplicity of STAP_MARK_* type/arity > permutations). But maybe there is a better way. >=20 I think that duplicating the number of marker macros could easily make them unflexible and ugly. This is why I am trying to come with this generic macro. > Also, while regparm(0) may provide some comfort on x86, is there good > reason to believe that the same trick works (and will continue to > work) on non-x86 platforms to invoke a non-varargs callee with a > varargs caller? >=20 Good point, I will setup a va_args in the probe. When correctly used, howev= er, there is no need to use the format string : we can directly get the variabl= es =66rom the var arg list if we know in advance what the string will be. 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-13748-1159226909-0001-2 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) iD8DBQFFGGYcPyWo/juummgRAjaRAJ4gozyOwwBPAZLK8ZPeYZpSmmwPPACgiGzU 4TE7TeG/27neMtFCOy6LTbg= =Bxty -----END PGP SIGNATURE----- --=_Krystal-13748-1159226909-0001-2-- - 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/