[lttng-dev] Probleme with live session on LTTng 2.7.0

Fri Jun 8 11:19:54 EDT 2018

Hi Thierry,

See -> https://lttng.org/docs/v2.10/#doc-lttng-live

Note that this is the documentation for lttng stable 2.10. Not 2.7, still it is as I recall pretty much unchanged since 

This should look like this for you.

On the 192.168.0.1 host:

lttng-relayd -vvv --control-port='tcp://0.0.0.0:5342' --data-port='tcp://0.0.0.0:5343' --live-port='tcp://localhost:5344'

If you plan on using the 5342,5344 and localhost:5344 ports, you can start lttng-relayd without these options since they are the default values.
Otherwise change those values.

Note that for the 5342 and 5343 ports the lttng-relayd process listen on all interfaces, the live port is only accessible from the loopback interface (locally). 
Hence, for this particular configuration only a Babeltrace running on the 192.168.0.1 host will be able to connect to lttng-relayd to get "live" data.

The "-vvv" option put lttng-relayd in verbose mode. Just in case we need to do more serious investigation.

At that point you can use netcat (nc) to test each port from the target side if you find it necessary. You should see activity on connection in the lttng-relayd logs.

On the target:

For the sake of knowing what is going on and get some verbose data if something does not go according to plan, you can start lttng-sessiond in verbose mode.

In a separate shell (running with sudo to get kernel tracing):
sudo lttng-sessiond -vvv

In another shell (considering your user is either root or in the tracing group):

lttng create my_session_name --set-url='net://192.168.0.1:5342:5343' --live
lttng enable-channel ... (your channel configuration if needed)
lttng enable-event ... (your specific event)
lttng start

On the 192.168.0.1 host:

You should be able to list the live session from lttng-relayd using the following:

babeltrace -i lttng-live net://localhost

>From the output of the last command you get the complete path that you need to use to actually connect Babeltrace to the live session.

babeltrace -i lttng-live net://localhost/host/<your hostname>/<session-name>

You should now see event coming in.

Hope this help.

Cheers

----- Original Message -----
> From: "BADEUIL Thierry" <thierry.badeuil at thalesgroup.com>
> To: "Jonathan Rajotte-Julien" <jonathan.rajotte-julien at efficios.com>
> Cc: "lttng-dev" <lttng-dev at lists.lttng.org>
> Sent: Friday, June 8, 2018 10:50:20 AM
> Subject: RE: [lttng-dev] Probleme with live session on LTTng 2.7.0

> Hello,
> 
> I plan to consume trace events as soon as possible as they are produced using
> BabelTrace. I do NOT want to start analysis after all tracing is done.
> 
> So ?
> 
> Cheers
> 
> Thierry BADEUIL
> THALES COMMUNICATIONS
> T : +33 1 46 133 591
> (  : +33 6 85 51 28 16
>  : thierry.badeuil at thalesgroup.com
> 
> -----Message d'origine-----
> De : Jonathan Rajotte-Julien [mailto:jonathan.rajotte-julien at efficios.com]
> Envoyé : vendredi 8 juin 2018 16:28
> À : BADEUIL Thierry
> Cc : lttng-dev
> Objet : Re: [lttng-dev] Probleme with live session on LTTng 2.7.0
> 
> Hi Thierry,
> 
> I also forgot to mention that there might some confusion on your end regarding
> the "live" mode.
> 
> LTTng have two "main" network streaming mode, normal streaming and live
> streaming.
> 
> The normal streaming is useful in scenario where you perform analysis after all
> tracing is done.
> This is the mode you are currently using in your example.
> 
> The "live" mode is mostly used when you are interesting in consuming trace
> events as soon as possible as they are produced using Babeltrace.
> 
> Which mode do you plan on using?
> 
> Cheers
> 
> 
> ----- Original Message -----
>> From: "Jonathan Rajotte-Julien" <jonathan.rajotte-julien at efficios.com>
>> To: "BADEUIL Thierry" <thierry.badeuil at thalesgroup.com>
>> Cc: "lttng-dev" <lttng-dev at lists.lttng.org>
>> Sent: Friday, June 8, 2018 10:10:44 AM
>> Subject: Re: [lttng-dev] Probleme with live session on LTTng 2.7.0
> 
>> Hi Thierry,
>> 
>> ----- Original Message -----
>>> From: "BADEUIL Thierry" <thierry.badeuil at thalesgroup.com>
>>> To: lttng-dev at lists.lttng.org
>>> Sent: Friday, June 8, 2018 9:45:44 AM
>>> Subject: [lttng-dev] Probleme with live session on LTTng 2.7.0
>> 
>>> Dear all,
>>> 
>>> 
>>> 
>>> I have problem with LTTng in live mode : I would like to send trace with TCP
>>> from my target to a Linux Computer. I will use babletrace on the Linux
>>> Computer.
>> 
>> LTTng 2.7 is not officially supported by the opensource community anymore.
>> Please upgrade if possible.
>> 
>>> 
>>> 
>>> 
>>> Here is what I try to do on my target with LTTng 2.7.0 :
>>> 
>>> o   Lttng create test –U net://192.168.0.1:5151
>> 
>> Did you start a lttng-relayd process on the 192.168.0.1 host? How was it
>> started?
>> 
>>> 
>>> o   Lttng enable-event –k sched_switch
>>> 
>>> o   I got an error : “Error: sched_switch: Unable to connect to lttng-relayd
>>> (channel channel0, session test)”
>>> 
>>> 
>>> 
>>> Then I tried :
>>> 
>>> o   Lttng-relayd –d
>> 
>> Was this done on the same machine where you run "lttng create" or on the
>> 192.168.0.1 host?
>> 
>>> 
>>> o   Lttng create test –U net://192.168.0.1:5151
>> 
>> 5151 is not the default port for lttng-relayd. Unless you specified custom port
>> at lttng-relayd start, the default port are 5342:5343:5344.
>> See the lttng-relayd man page for more information.
>> 
>>> 
>>> o   Lttng enable-event –k sched_switch
>>> 
>>> o   I got the same error
>>> 
>>> 
>>> 
>>> The IP address of the Linux Computer is 192.168.0.1 and the port 5151 is
>>> open.
>>> 
>>> 
>>> 
>>> Why ?
>>> 
>>> 
>>> 
>>> Thierry BADEUIL
>>> 
>>> THALES COMMUNICATIONS
>>> 
>>> ( : +33 1 46 133 591
>>> 
>>> È  : +33 6 85 51 28 16
>>> 
>>> * :  <mailto:thierry.badeuil at fr.thalesgroup.com>
>>> thierry.badeuil at thalesgroup.com
>>> 
>>> 
>>> 
>>> 
>>> _______________________________________________
>>> lttng-dev mailing list
>>> lttng-dev at lists.lttng.org
>>> https://lists.lttng.org/cgi-bin/mailman/listinfo/lttng-dev
>> _______________________________________________
>> lttng-dev mailing list
>> lttng-dev at lists.lttng.org
> > https://lists.lttng.org/cgi-bin/mailman/listinfo/lttng-dev