[lttng-dev] Beginner question: how to inspect scheduling of multi-threaded user application?

[Jonathan Rajotte Julien]

Hi,


On 2016-09-15 10:36 AM, David Aldrich wrote:
> Hi
>
> I'm afraid I'm still struggling with getting started with lttng. To recap, I want to use lttng + TraceCompass to monitor the scheduling of threads in my multi-threaded C++ application on Ubuntu.
>
> Here is my session:
>
> $ sudo pkill lttng-sessiond
> $ sudo lttng-sessiond
> Error: Already running daemon.

Would you happen to have installed lttng via the ppa or apt-get/equivalent.

If I remember correctly those package install an actual daemon. If you 
kill it, it will get re spawned.

Make sure that add your user to the tracing group then log out/log in.

Cheers
>
> $ lttng create demo_session Spawning a session daemon Session demo_session created.
> Traces will be written in /home/<snip>/lttng-traces/demo_session-20160915-152653
> <snip>:~$ PERROR [14956/14964]: 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.
>
> $ sudo lttng enable-event -k sched_switch -s demo_session
> Error: Event sched_switch: Session name not found (channel channel0, session demo_session)
> Warning: Some command(s) went wrong
>
> As you can see, each of these command generated a warning or error.  Please will you suggest where I am going wrong?
>
> Best regards
>
> David
>

-- 
Jonathan R. Julien
Efficios