Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1762151Ab3IDGta (ORCPT ); Wed, 4 Sep 2013 02:49:30 -0400 Received: from LGEMRELSE7Q.lge.com ([156.147.1.151]:43262 "EHLO LGEMRELSE7Q.lge.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1762139Ab3IDGt0 (ORCPT ); Wed, 4 Sep 2013 02:49:26 -0400 X-AuditID: 9c930197-b7b44ae00000347f-56-5226d7f47110 From: Namhyung Kim To: Hemant 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> Date: Wed, 04 Sep 2013 15:49:24 +0900 In-Reply-To: <5225E2C5.3080001@linux.vnet.ibm.com> (Hemant's message of "Tue, 03 Sep 2013 18:53:17 +0530") Message-ID: <87a9jtt72j.fsf@sejong.aot.lge.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/24.1 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain X-Brightmail-Tracker: AAAAAA== Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2340 Lines: 51 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. > 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/