Hi David,
Hi Jonathan and Francis
Thanks for your helpful replies. I am having a bit of trouble implementing
your suggestions. Here is my session:
$ lttng create
Spawning a session daemon
PERROR [2885/2893]: bind inet: Address already in use (in
lttcomm_bind_inet_sock() at inet.c:109)
Warning: An other session daemon is using this JUL port. JUL support will be
deactivated not interfering with the tracing.
Session auto-20160826-083823 created.
Traces will be written in <snip>/lttng-traces/auto-20160826-083823
First let's get a clean state.
Make sure the user is in the "tracing" group if you plan to do kernel
tracing from the user.
groups UsernameHere
If not make sure to add the user to the 'tracing' group.
Kill all lttng related daemon.
sudo pkill lttng-sessiond
sudo pkill lttng-relayd
If you installed it via apt-get/ppa a lttng-sessiond should spawn
otherwise start one with sudo:
sudo lttng-sessiond
or
sudo lttng-sessiond -b
or
sudo lttng-sessiond -d
See lttng-sessiond man page for information regarding these options.
$ sudo lttng enable-event -k sched_switch
Error: Event sched_switch: Session name not found (channel channel0, session
auto-20160826-083823)
Warning: Some command(s) went wrong
This is due to the fact that the state (current session) is kept on a
per-user basis under ~/.lttng. You started the session with another user
and then used sudo for "lttng enable-event".
If you want to pass the session name most of the commands support the
'-s SessionNameHere' option.
There seem to be two problems here:
1) How to kill a lttng daemon that is already running?
2) How to specify a session?
Sorry that these are basic questions. I would be grateful if you can help
please.
Np.
Make sure to check http://lttng.org/docs/ if you did not already.
Cheers
Best regards
David
From: Jonathan Rajotte [mailto:jonathan.r.jul...@gmail.com]
Sent: 24 August 2016 17:39
To: Francis Deslauriers <francis.deslauri...@mail.utoronto.ca>
Cc: David Aldrich <david.aldr...@emea.nec.com>; lttng-dev@lists.lttng.org
Subject: Re: [lttng-dev] Beginner question: how to inspect scheduling of
multi-threaded user application?
Sorry had a sending problem.
Here is the rest.
On Wed, Aug 24, 2016 at 12:35 PM, Jonathan Rajotte
<jonathan.r.jul...@gmail.com<mailto:jonathan.r.jul...@gmail.com>> wrote:
Hi,
On Aug 24, 2016 12:18 PM, "Francis Deslauriers"
<francis.deslauri...@mail.utoronto.ca<mailto:francis.deslauri...@mail.utoronto.ca>> wrote:
Hi David,
If you specifically want to trace the scheduling of the threads of your app,
you don't need custom tracepoints.
Enabling the sched_switch kernel event will give you both of cpu id and thread
id. Look at the cpu_id and next_tid fields.
You can enable the sched_switch event using : lttng enable-event -k sched_switch
In TraceCompass you can inspect this data with the control flow view and the
Ressource view under the Kernel analysis node under the trace node in the
project explorer.
I'm not sure of the base requirement for those views you can use the safe
enable-event:
replace "safe" by "easiest".
lttng enable-event -k 'sched*'
You can also use "lttng track" to limi the gathering of event to a certain pid.
Another way to reduce the scope would be to filter per procname:
lttng create
lttng add-context -k -t procname
lttng enable-event 'sched*' --filter '$ctx.procname == "PROCNAMEHERE"'
lttng start
PROCNAMEHERE can contain '*' wildcard. See the man page for more information.
Cheers
Cheers,
Francis
2016-08-24 3:17 GMT-04:00 David Aldrich
<david.aldr...@emea.nec.com<mailto:david.aldr...@emea.nec.com>>:
Hi
I am new to tracing in Linux and to lttng. I have a multi-threaded user
application and I want to see:
1) When the threads are scheduled to run
2) Which cores the threads are running on.
I have installed lttng on Ubuntu 14.04 LTS. I am expecting to visualise the
trace using TraceCompass.
I have read the following doc section:
http://lttng.org/docs/#doc-tracing-your-own-user-application
In order to collect my trace, must I define custom tracepoint definitions ( in
a tracepoint provider header file ), and insert tracepoints into my user
application, or is there a simpler way of achieving my goal?
Best regards
David
_______________________________________________
lttng-dev mailing list
lttng-dev@lists.lttng.org<mailto:lttng-dev@lists.lttng.org>
https://lists.lttng.org/cgi-bin/mailman/listinfo/lttng-dev
_______________________________________________
lttng-dev mailing list
lttng-dev@lists.lttng.org<mailto:lttng-dev@lists.lttng.org>
https://lists.lttng.org/cgi-bin/mailman/listinfo/lttng-dev
--
Jonathan Rajotte Julien
Click
here<https://www.mailcontrol.com/sr/unEwdsSZGlHGX2PQPOmvUmQbZlJUA6MYaHsjpmEwGrBfobipAMW1ZCPMpsLI18FS3tdTuAJyxqmiyla!1rT5xQ==>
to report this email as spam.
_______________________________________________
lttng-dev mailing list
lttng-dev@lists.lttng.org
https://lists.lttng.org/cgi-bin/mailman/listinfo/lttng-dev
--
Jonathan R. Julien
Efficios
_______________________________________________
lttng-dev mailing list
lttng-dev@lists.lttng.org
https://lists.lttng.org/cgi-bin/mailman/listinfo/lttng-dev
