Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751270AbWISWeq (ORCPT ); Tue, 19 Sep 2006 18:34:46 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751345AbWISWep (ORCPT ); Tue, 19 Sep 2006 18:34:45 -0400 Received: from mx1.redhat.com ([66.187.233.31]:19396 "EHLO mx1.redhat.com") by vger.kernel.org with ESMTP id S1751270AbWISWep (ORCPT ); Tue, 19 Sep 2006 18:34:45 -0400 Message-ID: <45106ED7.7010603@redhat.com> Date: Tue, 19 Sep 2006 18:27:35 -0400 From: Satoshi Oshima User-Agent: Thunderbird 1.5.0.7 (X11/20060913) MIME-Version: 1.0 To: Mathieu Desnoyers CC: Vara Prasad , Martin Bligh , prasanna@in.ibm.com, Andrew Morton , "Frank Ch. Eigler" , 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 Subject: Re: [PATCH] Linux Kernel Markers References: <20060918234502.GA197@Krystal> <20060919081124.GA30394@elte.hu> <451008AC.6030006@google.com> <20060919154612.GU3951@redhat.com> <4510151B.5070304@google.com> <20060919093935.4ddcefc3.akpm@osdl.org> <45101DBA.7000901@google.com> <20060919063821.GB23836@in.ibm.com> <45102641.7000101@google.com> <4510413F.2030200@us.ibm.com> <20060919191652.GC30556@Krystal> In-Reply-To: <20060919191652.GC30556@Krystal> Content-Type: text/plain; charset=ISO-2022-JP Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1794 Lines: 41 Mathieu Desnoyers wrote: > * Vara Prasad (prasadav@us.ibm.com) wrote: >> Martin Bligh wrote: >> >>> [...] >>> Depends what we're trying to fix. I was trying to fix two things: >>> >>> 1. Flexibility - kprobes seem unable to access all local variables etc >>> easily, and go anywhere inside the function. Plus keeping low overhead >>> for doing things like keeping counters in a function (see previous >>> example I mentioned for counting pages in shrink_list). >>> >> Using tools like systemtap on can consult DWARF information and put >> probes in the middle of the function and access local variables as well, >> that is not the real problem. The issue here is compiler doesn't seem to >> generate required DWARF information in some cases due to optimizations. >> The other related problem is when there exists debug information, the >> way to specify the breakpoint location is using line number which is not >> maintainable, having a marker solves this problem as well. Your proposal >> still doesn't solve the need for markers if i understood correctly. >> > > His implementation makes a heavy use of a marker mechanism : this is exactly > what permits to create the instrumented objects from the same source code, but > with different #defines. Djprobes don't depend on markers. Actually, markers help to find the safe place to probe, but they are not necessary. At least, instructions that are more than 4 byte are probable. As Vara pointed out, we are developing the tools that find the safe place for djprobes. Satoshi OSHIMA - 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/