Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932203AbWITSPp (ORCPT ); Wed, 20 Sep 2006 14:15:45 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932204AbWITSPp (ORCPT ); Wed, 20 Sep 2006 14:15:45 -0400 Received: from opersys.com ([64.40.108.71]:260 "EHLO www.opersys.com") by vger.kernel.org with ESMTP id S932201AbWITSPm (ORCPT ); Wed, 20 Sep 2006 14:15:42 -0400 Message-ID: <451187A5.4010501@opersys.com> Date: Wed, 20 Sep 2006 14:25:41 -0400 From: Karim Yaghmour Reply-To: karim@opersys.com Organization: Opersys inc. User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.8.0.6) Gecko/20060804 Fedora/1.0.4-0.5.1.fc5 SeaMonkey/1.0.4 MIME-Version: 1.0 To: "Frank Ch. Eigler" CC: Masami Hiramatsu , Martin Bligh , prasanna@in.ibm.com, Andrew Morton , Ingo Molnar , Mathieu Desnoyers , 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 Subject: Re: [PATCH] Linux Kernel Markers References: <4510151B.5070304@google.com> <20060919093935.4ddcefc3.akpm@osdl.org> <45101DBA.7000901@google.com> <20060919063821.GB23836@in.ibm.com> <45102641.7000101@google.com> <20060919070516.GD23836@in.ibm.com> <451030A6.6040801@google.com> <45105B5E.9080107@opersys.com> <451141B1.40803@hitachi.com> <451178B0.9030205@opersys.com> <20060920180808.GI18646@redhat.com> In-Reply-To: <20060920180808.GI18646@redhat.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1358 Lines: 38 Hello Frank, Frank Ch. Eigler wrote: > My interpretation of Martin's Monday proposal is that, if implemented, > we wouldn't need any of this nop/int3 stuff. If function being > instrumented were recompiled on-the-fly, then it could sport plain & > direct C-level calls to the instrumentation handlers. Absolutely. I guess the length of these threads is just fertile ground for misunderstandings. Basically what Hiramatsu-san and myself were discussing was just the mechanism for selecting/ forking in between the uninstrumented function and the instrumented one. So, to recap: If you had 100,000 instrumentation points in the scheduler (obviously a totally bogus number here ...) you'd have 2 functions: 1- one with no instrumentation at all, but with a 5byte filler such as the one presented by Hiramatsu-san. 2- one with the instrumentation. Early in the proposal, the mechanics of switching in between "1" and "2" seemed to be problematic, but I think with Hiramatsu-san's proposal and, on the x86, djprobes, we've got it figured out. Let me know if I'm not providing enough detail. Thanks, Karim - 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/