Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932204AbWITSYh (ORCPT ); Wed, 20 Sep 2006 14:24:37 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932210AbWITSYh (ORCPT ); Wed, 20 Sep 2006 14:24:37 -0400 Received: from smtp-out.google.com ([216.239.45.12]:63692 "EHLO smtp-out.google.com") by vger.kernel.org with ESMTP id S932204AbWITSYf (ORCPT ); Wed, 20 Sep 2006 14:24:35 -0400 DomainKey-Signature: a=rsa-sha1; s=beta; d=google.com; c=nofws; q=dns; h=received:message-id:date:from:user-agent: x-accept-language:mime-version:to:cc:subject:references:in-reply-to: content-type:content-transfer-encoding; b=NC2VIvIixoBtXgEYt8DUHJ6Dxb2k6OXLZTMDZ35DS/lhlIcX/qtinh8tf1eHIBcGk Q8dPDsJQAS5HnTgMWtRfA== Message-ID: <451186F2.3060702@google.com> Date: Wed, 20 Sep 2006 11:22:42 -0700 From: Martin Bligh User-Agent: Mozilla Thunderbird 1.0.7 (X11/20051011) X-Accept-Language: en-us, en MIME-Version: 1.0 To: "Frank Ch. Eigler" CC: Karim Yaghmour , Masami Hiramatsu , 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; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1208 Lines: 31 Frank Ch. Eigler wrote: > Hi - > > On Wed, Sep 20, 2006 at 01:21:52PM -0400, Karim Yaghmour wrote: > > >>[...] IOW, we should be able to do what Martin suggests fairly >>easily (if we agree on a 5-byte "null" jump at the entry of >>functions of interest). Right? [...] > > > 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. It's looking to me like it might still need djprobes to implement, in order to get the atomic and safe switchover from the original function into the traced one. All rather sad, but seems to be true from all the CPU errata, etc. If anyone can see a way round that, I'd love to hear it. What it would give you above and beyond djprobes is an easier and more flexible way to actually do the instrumentation itself. M. - 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/