Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932455Ab3IDSCJ (ORCPT ); Wed, 4 Sep 2013 14:02:09 -0400 Received: from e28smtp06.in.ibm.com ([122.248.162.6]:36739 "EHLO e28smtp06.in.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752354Ab3IDSCE (ORCPT ); Wed, 4 Sep 2013 14:02:04 -0400 Message-ID: <522771A6.4030504@linux.vnet.ibm.com> Date: Wed, 04 Sep 2013 23:15:10 +0530 From: Hemant User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130625 Thunderbird/17.0.7 MIME-Version: 1.0 To: Namhyung Kim CC: Masami Hiramatsu , Ingo Molnar , linux-kernel@vger.kernel.org, srikar@linux.vnet.ibm.com, peterz@infradead.org, oleg@redhat.com, mingo@redhat.com, anton@redhat.com, systemtap@sourceware.org Subject: Re: [RFC PATCH 0/2] Perf support to SDT markers References: <20130903072944.4793.93584.stgit@hemant-fedora> <20130903082503.GA20732@gmail.com> <5225A937.2050507@hitachi.com> <5225E2C5.3080001@linux.vnet.ibm.com> <87a9jtt72j.fsf@sejong.aot.lge.com> In-Reply-To: <87a9jtt72j.fsf@sejong.aot.lge.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-TM-AS-MML: No X-Content-Scanned: Fidelis XPS MAILER x-cbid: 13090417-9574-0000-0000-0000097AB3E4 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2521 Lines: 55 On 09/04/2013 12:19 PM, Namhyung Kim wrote: > On Tue, 03 Sep 2013 18:53:17 +0530, Hemant wrote: >> On 09/03/2013 02:47 PM, Masami Hiramatsu wrote: >>> (2013/09/03 17:25), Ingo Molnar wrote: >>>> * Hemant Kumar Shaw wrote: >>>> >>>>> This series adds support to perf to list and probe into the SDT markers. >>>>> The first patch implements listing of all the SDT markers present in >>>>> the ELFs (executables or libraries). The SDT markers are present in the >>>>> .note.stapsdt section of the elf. That section can be traversed to list >>>>> all the markers. Recognition of markers follows the SystemTap approach. >>>>> >>>>> The second patch will allow perf to probe into these markers. This is >>>>> done by writing the marker name and its offset into the >>>>> uprobe_events file in the tracing directory. >>>>> Then, perf tools can be used to analyze perf.data file. >>>> Please provide a better high level description that explains the history >>>> and scope of SDT markers, how SDT markers get into binaries, how they can >>>> be used for probing, a real-life usage example that shows something >>>> interesting not possible via other ways, etc. >>> Indeed, and also I'd like to know what versions of SDT this support, >>> and where we can see the technical document of that. As far as I know, >>> the previous(?) SDT implementation also involves ugly semaphores. >>> Have that already gone? > It seems it's not. I see the SDT v3 document still mentions semaphores. Yes, It still mentions semaphores and I will be handling these semaphores. Thanks Hemant > > >> This link shows an example of marker probing with Systemtap: >> https://sourceware.org/systemtap/wiki/AddingUserSpaceProbingToApps > I think the link below would be more helpful for us :) > > http://sourceware.org/systemtap/wiki/UserSpaceProbeImplementation > > Thanks, > Namhyung > >> - Markers in binaries : >> These SDT markers are present in the ELF in the section named >> ".note.stapsdt". >> Here, the name of the marker, its provider, type, location, base >> address, semaphore address, arguments are present. >> We can retrieve these values using the members name_off and desc_off in >> Nhdr structure. If these are not enabled, they are present in the ELF >> as nop. -- 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/