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Paul E. McKenney | 20 May 17:56
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Re: [lttng-dev] [PATCH] configure: exit if urcu/uatomic.h is not found

On Sun, May 20, 2012 at 11:28:29AM -0400, Mathieu Desnoyers wrote:
> * Christoph Hellwig (hch@...) wrote:
> > We could have a local include/uatomic.h that includes either based on
> > which one is available, still erroring out if none is present.
> > 
> > I've cced the LTTng list to se if using the old uatomic_arch.h header
> > from outside librcu is something we should do at all.
> 
> Hi Christoph,
> 
> Hrm, 0.4.1 is really old (2010-02-12). We did migrate some header names
> and clean up some API namespacing back then between 0.4 and 0.5, so we
> would not have to do it when the project would get more exposure. In
> terms of way forward, we were planning to remove urcu/uatomic_arch.h
> after a rather long deprecation period, being replaced by
> urcu/uatomic.h. As you noticed, there has been a deprecation #warning in
> place since the move has been done.
> 
> If you want to keep compatibility with the old 0.4.x version of liburcu
> for a longer time, my recommendation would be to add a configure.ac
> check for urcu/uatomic.h. It it is missing, then check for
> urcu/uatomic_arch.h. This would specify a preprocessor macro that will
> select either in a wrapper header within the sheepdog project.
> If you only rely on uatomic, doing so should handle deprecation of the
> older liburcu 0.4.x support within sheepdog at some point in the future
> if need be.

Another approach is to have sheepdog simply download the desired version
of liburcu if it doesn't like the one it finds.  ;-)
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Mathieu Desnoyers | 16 May 01:48

[CFP] Tracing Micro-conference at LPC2012 (August 28-30, San Diego)

Hi,

We are organizing a tracing micro-conference taking place in San Diego,
within Linux Plumbers Conference 2012. The micro-conference is planned
to be held somewhere between August 28 and 30, in San Diego, CA.

If you are interested to present, please don't hesitate to get in touch
with us quickly (ideally within this week, or next week), since
deadlines are approaching.

Our intent is to gather people involved in development and users of
tracing tools and trace analysis tools to allow discussing the latest
developments, allow users to express their needs, and generally ensure
that developers and end users understand each other.

We are welcoming presentations from both end users and developers, on
topics covering, but not limited to:

- Trace collection and extraction,
- Trace filtering,
- Trace aggregation,
- Trace formats,
- Tracing multi-core systems,
- Trace abstraction,
- Trace modeling,
- Automated trace analysis (e.g. dependency analysis),
- Tracing large clusters and distributed systems,
- Hardware-level tracing (e.g. DSP, GPU, bare-metal),
- Trace visualisation,
- Interaction between debugging and tracing,
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Mathieu Desnoyers | 3 Feb 04:43

[RELEASE] LTTng 2.0 prerelease bundle 20120202

LTTng, the Linux Trace Toolkit Next Generation, is a highly efficient
full system tracing solution toolchain. It is composed of several
components to allow tracing of the kernel, of userspace, trace viewing
and analysis and trace streaming. LTTng is open source software.

This bundle (20120202) contains:

lttng-modules-2.0-pre12.tar.bz2   - Linux kernel tracer
lttng-ust-1.9.5.tar.gz            - User-space tracing
lttng-tools-2.0-pre19.tar.bz2     - Tracer control (for kernel and
                                    userspace tracing)
babeltrace-0.9.tar.bz2            - Trace to text pretty printer
userspace-rcu-0.6.7.tar.bz2       - User-level synchronization lib

This will be the last prerelease bundle before Release Candidate 1. From
rc1, LTTng 2.0 will enter in feature-freeze mode until 2.0 final, which
is expected around Feb. 15. Testing is therefore more than very
welcome!

You can get a the current release "bundle" (recommanded set of packages)
at the following URL:

http://lttng.org/bundles/

Project website: http://lttng.org
Download link: http://lttng.org/lttng2.0
(please refer to the README files for installation instructions and
lttng-tools doc/quickstart.txt for usage information)

--

--
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Stefan Hajnoczi | 11 Jan 10:30
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Re: [lttng-dev] [RFC PATCH v2 0/4] simpletrace : support var num of args and strings.

On Tue, Jan 10, 2012 at 5:29 PM, Mathieu Desnoyers
<mathieu.desnoyers <at> efficios.com> wrote:
> Hi Stefan,
>
> * Stefan Hajnoczi (stefanha <at> gmail.com) wrote:
>> On Tue, Jan 10, 2012 at 12:14 AM, Mathieu Desnoyers
>> <mathieu.desnoyers <at> efficios.com> wrote:
>> > This is needed to (very soon) add support for sdt.h in LTTng-UST 2.0, so
>> > systemtap and gdb can hook into tracepoints declared by lttng-ust 2.0.
>>
>> If lttng supports sdt.h in the future will it also provide a dtrace(1)
>> wrapper?  I'm wondering if we can boil it down to the common DTrace
>> code that we already use in QEMU for SystemTap and that the
>> SmartOS/Illumos folks have used with DTrace.
>
> What we plan to provide is the other way around: because we want to keep
> the TRACEPOINT_EVENT description, which specify the mapping between the
> arguments passed to the tracepoint() and what is to be serialized into
> the trace, as part of the application code, we require that the
> instrumentation be specified in the form of TRACEPOINT_EVENT and called
> with tracepoint(). The bonus here is that the tracepoint() macro can
> embed a STAP_PROBEV() call, which should be compatible with systemtap
> and gdb.

I see, thanks for explaining.

> One more point is that tracepoints put all side-effects of the
> parameters passed to the tracepoint() macro inside the "instrumentation
> enabled" code path (pointer dereferenced, offsets computation, functions
> called...). Therefore, when tracepoints are disabled, they just cost a
(Continue reading)

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Mathieu Desnoyers | 10 Jan 18:29

Re: [lttng-dev] [RFC PATCH v2 0/4] simpletrace : support var num of args and strings.

Hi Stefan,

* Stefan Hajnoczi (stefanha <at> gmail.com) wrote:
> On Tue, Jan 10, 2012 at 12:14 AM, Mathieu Desnoyers
> <mathieu.desnoyers <at> efficios.com> wrote:
> > This is needed to (very soon) add support for sdt.h in LTTng-UST 2.0, so
> > systemtap and gdb can hook into tracepoints declared by lttng-ust 2.0.
> 
> If lttng supports sdt.h in the future will it also provide a dtrace(1)
> wrapper?  I'm wondering if we can boil it down to the common DTrace
> code that we already use in QEMU for SystemTap and that the
> SmartOS/Illumos folks have used with DTrace.

What we plan to provide is the other way around: because we want to keep
the TRACEPOINT_EVENT description, which specify the mapping between the
arguments passed to the tracepoint() and what is to be serialized into
the trace, as part of the application code, we require that the
instrumentation be specified in the form of TRACEPOINT_EVENT and called
with tracepoint(). The bonus here is that the tracepoint() macro can
embed a STAP_PROBEV() call, which should be compatible with systemtap
and gdb.

Another point worth noting is that sdt provider uses a breakpoint to
call the probes from the application instrumentation sites, which brings
an added overhead compared to tracepoints when it is activated. This is
another reason for staying with tracepoints and not use SDT as is within
lttng-ust.

One more point is that tracepoints put all side-effects of the
parameters passed to the tracepoint() macro inside the "instrumentation
(Continue reading)

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Mathieu Desnoyers | 21 Dec 22:48

[PATCH] staging: Remove LTTng from MAINTAINERS file

LTTng has been removed from the staging tree. Complete this removal by
removing the LTTng entry from the MAINTAINERS file.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers <at> efficios.com>
CC: Greg Kroah-Hartman <gregkh <at> suse.de>
CC: Ingo Molnar <mingo <at> elte.hu>
CC: Peter Zijlstra <peterz <at> infradead.org>
---
diff --git a/MAINTAINERS b/MAINTAINERS
index f3bb825..1514f7a 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -4132,13 +4132,6 @@ W:	http://ltp.sourceforge.net/
 T:	git git://ltp.git.sourceforge.net/gitroot/ltp/ltp-dev
 S:	Maintained

-LTTng (Linux Trace Toolkit Next Generation)
-M:	Mathieu Desnoyers <mathieu.desnoyers <at> efficios.com>
-L:	lttng-dev <at> lists.lttng.org (moderated for non-subscribers)
-W:	http://lttng.org
-S:	Maintained
-F:	drivers/staging/lttng/
-
 M32R ARCHITECTURE
 M:	Hirokazu Takata <takata <at> linux-m32r.org>
 L:	linux-m32r <at> ml.linux-m32r.org (moderated for non-subscribers)

--

-- 
Mathieu Desnoyers
Operating System Efficiency R&D Consultant
(Continue reading)

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Mathieu Desnoyers | 21 Dec 22:48

[PATCH] staging: Remove LTTng from MAINTAINERS file

LTTng has been removed from the staging tree. Complete this removal by
removing the LTTng entry from the MAINTAINERS file.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers <at> efficios.com>
CC: Greg Kroah-Hartman <gregkh <at> suse.de>
CC: Ingo Molnar <mingo <at> elte.hu>
CC: Peter Zijlstra <peterz <at> infradead.org>
---
diff --git a/MAINTAINERS b/MAINTAINERS
index f3bb825..1514f7a 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -4132,13 +4132,6 @@ W:	http://ltp.sourceforge.net/
 T:	git git://ltp.git.sourceforge.net/gitroot/ltp/ltp-dev
 S:	Maintained

-LTTng (Linux Trace Toolkit Next Generation)
-M:	Mathieu Desnoyers <mathieu.desnoyers <at> efficios.com>
-L:	lttng-dev <at> lists.lttng.org (moderated for non-subscribers)
-W:	http://lttng.org
-S:	Maintained
-F:	drivers/staging/lttng/
-
 M32R ARCHITECTURE
 M:	Hirokazu Takata <takata <at> linux-m32r.org>
 L:	linux-m32r <at> ml.linux-m32r.org (moderated for non-subscribers)

--

-- 
Mathieu Desnoyers
Operating System Efficiency R&D Consultant
(Continue reading)

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Andy Howell | 4 Jun 22:33

lttv display questions

I'm using linux 2.6.30-rc5, lttv 0.12.14-15052009, and lttctl 0.64-14012009

What is the meaning of the dots about the graph lines for thread in the "Control Flow Viewer"?

When I start up, I see a number of errors like:

** (lttv.real:24284): WARNING **: No channel for marker named block._blk_request_complete
found

and

** (lttv.real:24284): WARNING **: 5521 events lost so far in tracefile /tmp/t2/vm_state_0
at block 1

Is there anything I can do to cut down on the lost events?

Thanks,

	Andy
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Andrew McDermott | 22 Oct 12:02
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kernel Oops in ltt_buffer_begin_callback / ltt_create_buf_file_callback


I am using:

  linux-2.6.27-lttng-0.43
  ltt-control-0.55-16102008

and tried to create a trace with:

  /usr/local/ltt-control-0.55/bin/lttctl -x 32768 -n trace4 -d -l /mnt/debugfs/ltt -t /tmp/trace4

but that gave me a SEGV followed by the following Oops:

    [82616.737763] Creating trace trace4
    [82616.740990] BUG: unable to handle kernel NULL pointer dereference at 00000008
    [82616.740996] IP: [<c033aa9a>] ltt_buffer_begin_callback+0x3a/0x16c
    [82616.741014] *pde = 00000000 
    [82616.741019] Oops: 0000 [#1] SMP 
    [82616.741023] LTT NESTING LEVEL : 0
    [82616.741026] Modules linked in: ltt_control ltt_statedump
    [82616.741032] 
    [82616.741035] Pid: 8561, comm: lttctl Not tainted (2.6.27-lttng-0.43 #5)
    [82616.741039] EIP: 0060:[<c033aa9a>] EFLAGS: 00010246 CPU: 0
    [82616.741043] EIP is at ltt_buffer_begin_callback+0x3a/0x16c
    [82616.741046] EAX: 00000000 EBX: f7060e00 ECX: efe62000 EDX: 00100000
    [82616.741049] ESI: 00000000 EDI: 00000000 EBP: eee93bf8 ESP: eee93bd8
    [82616.741052]  DS: 007b ES: 007b FS: 00d8 GS: 0033 SS: 0068
    [82616.741056] Process lttctl (pid: 8561, ti=eee92000 task=eecd3160 task.ti=eee92000)
    [82616.741058] Stack: dd4759f8 0000eff5 f7060e00 efe62000 00000000 efdca700 fffffff4 ec6e9600 
    [82616.741067]        eee93c24 c033af5a 00000000 00000100 e907f880 effe4c00 efe62000 00008000 
    [82616.741076]        ec6e9654 f7060e00 ec74a800 eee93c50 c033b869 f7060e00 f7060e00 effe4c00
(Continue reading)

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David Wuertele | 15 Sep 23:09
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MIPS linux-2.6.12 (highly patched) + LTTng-0.5.69 + ltt-control-0.10-12062006

I am having no success using LTTng to instrument an embedded MIPS system with a
vendor-supplied linux-2.6.12.  I tried many different versions of the LTTng
patches, but the only way I could get everything to compile and boot was as
follows:

  1.  port relayfs from 2.6.16 back to my 2.6.12, replaced all use of mutexes
      with semaphores.

  2.  backport atomic_cmpxchg from 2.6.16 to 2.6.12

  3.  integrate patch-2.6.16-lttng-0.5.69.tar.bz2

  4.  build ltt-control-0.10-12062006 and install it in an NFS rootfs

  5.  boot my kernel from NFS

  6.  mount -t tmpfs none /tmp
      mount -t tmpfs none /mnt
      mkdir -p /mnt/debugfs
      mount debugfs /mnt/debugfs -o rw

Here's the output from lttctl:

  bash-3.2# lttctl -n trace -d -l /mnt/debugfs/ltt -t /tmp/trace
  Linux Trace Toolkit Trace Control
  [4294701.895000] ltt_control : trace trace

  Controlling trace : trace

  Linux Trace Toolkit Trace Daemon
(Continue reading)

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Tim Bird | 8 Jul 21:52
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tracing wiki - no way to edit

I'm not sure who to send this to, but maybe someone here
knows what's up with the tracing wiki?

I was just at:
https://ltt.polymtl.ca/tracingwiki/index.php/TracingBook
and I thought I would edit one of the pages to add
some information.

There's no tab when you're not logged in.  I tried
to create an account, but I could not find a way to
do it.  Clicking on "log in/create account" takes
me to a login page.  There's no means that I can
see to create an account.

I tried to contact the administrator of the wiki
by clicking on "About TracingWiki" at the bottom
of the page, but the page does not exist.

If anyone knows who to contact about this, please
let me know.

Regards,
 -- Tim

=============================
Tim Bird
Architecture Group Chair, CE Linux Forum
Senior Staff Engineer, Sony Corporation of America
=============================
(Continue reading)

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