From: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
To: Hemant Kumar <hemant@linux.vnet.ibm.com>, acme@kernel.org
Cc: linux-kernel@vger.kernel.org, srikar@linux.vnet.ibm.com,
peterz@infradead.org, oleg@redhat.com,
hegdevasant@linux.vnet.ibm.com, mingo@redhat.com,
anton@redhat.com, systemtap@sourceware.org, namhyung@kernel.org,
aravinda@linux.vnet.ibm.com, penberg@iki.fi
Subject: Re: [PATCH v4 0/3] perf/sdt : Support for SDT markers
Date: Thu, 28 Aug 2014 11:20:00 -0000 [thread overview]
Message-ID: <53FF105B.1000103@hitachi.com> (raw)
In-Reply-To: <20140827213745.13454.46266.stgit@hemant-fedora>
(2014/08/28 6:43), Hemant Kumar wrote:
> The v3 patchset had some spacing errors because of my editor messing up during
> sending the patches. Resending the patchset again.
> This patchset helps in listing dtrace style markers(SDT) present in user space
> applications through perf.
> Notes/markers are placed at important places by the
> developers. They have a negligible overhead when not enabled.
> We can enable them and probe at these places and find some important information
> like the arguments' values, etc.
>
> We have lots of applications which use SDT markers today, like:
> Postgresql, MySql, Mozilla, Perl, Python, Java, Ruby, libvirt, QEMU, glib
>
> To add SDT markers into user applications:
> We need to have this header sys/sdt.h present.
> sys/sdt.h used is version 3.
> If not present, install systemtap-sdt-devel package (for fedora-18).
>
> Please refer to the Documentation patch (3rd patch in this series) to see how the
> SDT markers are added into a program.
>
> With this patchset,
> - Use perf to list the markers in the app:
> # perf list sdt ./user_app
>
> ./user_app :
> %user_app:foo_start
> %user_app:fun_start
>
> This link shows an example of marker probing with Systemtap:
> https://sourceware.org/systemtap/wiki/AddingUserSpaceProbingToApps
>
> Also, this link provides important info regarding SDT notes:
> http://sourceware.org/systemtap/wiki/UserSpaceProbeImplementation
>
> This patchset has undergone a lot of changes since it was first introduced.
> Hence, the patchset has now been subdivided for more simplicity and ease of
> review (thanks to the suggestion from Namhyung Kim). This contains the first 2
> of the 4 patches as suggested here:
> https://lkml.org/lkml/2014/7/20/284
BTW, does this series only contain list command support?
> - 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.
> 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.
>
> Changes since last series :
> - Subdivided the previous patchset into 4 patches to make it easier to review
> as suggested by Namhyung Kim. (This set includes first two of the four patches)
> - Made the required changes and some optimizations suggested by Masami, Namhyung
> and Andi.
>
> TODO:
> - Listing SDT events present in most of the binaries present in a system.
> - Maintaining a cache of the SDT events for faster lookup.
> - Add support to probe these SDT markers and integrate with a previous patch
> (support to perf to probe SDT markers) posted in lkml.
> https://lkml.org/lkml/2013/10/23/10
OK, I think we can postpone sdt-cache command, but this should go with
probe-side improvements, because if perf-list shows sdt markers, users
will be misled that the perf already supports sdt events.
I'm OK if we hold this on a non-released branch on acme's tree. But it
shouldn't be pushed to upstream without probe-side improvements.
Arnaldo, would you think that works on your tree?
Thank you,
--
Masami HIRAMATSU
Software Platform Research Dept. Linux Technology Research Center
Hitachi, Ltd., Yokohama Research Laboratory
E-mail: masami.hiramatsu.pt@hitachi.com
prev parent reply other threads:[~2014-08-28 11:20 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-08-28 3:42 Hemant Kumar
2014-08-28 3:43 ` [PATCH v4 1/3] perf/sdt : Raw SDT parsing functions Hemant Kumar
2014-08-29 7:22 ` Namhyung Kim
2014-08-28 3:50 ` [PATCH v4 2/3] perf/sdt : Support perf-list to print SDT events in a single file Hemant Kumar
2014-08-28 10:54 ` Masami Hiramatsu
2014-08-28 12:24 ` Hemant Kumar
2014-08-28 3:52 ` [PATCH v4 3/3] perf/sdt : Documentation for SDT events Hemant Kumar
2014-08-29 7:26 ` Namhyung Kim
2014-09-01 6:01 ` Masami Hiramatsu
2014-08-28 11:20 ` Masami Hiramatsu [this message]
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=53FF105B.1000103@hitachi.com \
--to=masami.hiramatsu.pt@hitachi.com \
--cc=acme@kernel.org \
--cc=anton@redhat.com \
--cc=aravinda@linux.vnet.ibm.com \
--cc=hegdevasant@linux.vnet.ibm.com \
--cc=hemant@linux.vnet.ibm.com \
--cc=linux-kernel@vger.kernel.org \
--cc=mingo@redhat.com \
--cc=namhyung@kernel.org \
--cc=oleg@redhat.com \
--cc=penberg@iki.fi \
--cc=peterz@infradead.org \
--cc=srikar@linux.vnet.ibm.com \
--cc=systemtap@sourceware.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).