[lttng-dev] process/thread-specific UST tracing

Mathieu Desnoyers mathieu.desnoyers at efficios.com
Fri May 15 15:15:16 EDT 2020

----- On May 15, 2020, at 1:16 PM, lttng-dev <lttng-dev at lists.lttng.org> wrote: 

> I am tracing a multiprocess/multithreaded code (MPI/OpenMP) using lttng-ust.
> Right now, I need to include process id and thread id for each event in order
> to generate process/thread indexed view of the traces. Is there a way that I
> can store per-process events into a specific buffer without mixing the events
> with other events that are generated on the same CPU? The same thing for
> per-thread events, I would like lttng or CTF to allow to store per-thread
> events in a specific buffer without mixing the events with other events on the
> same CPU channel. With that feature, I do not need to store process id and
> thread id in each event and then need to query all the events in order to
> collect per-process or per-thread event.

No, but you can use kernel tracing (lttng-modules) of the scheduler events (sched:*) to map 
the CPU number to the currently running thread and process at trace post-processing. 

By doing so, both current thread and process become implicit with the CPU number. 



> Thank you
> Yonghong

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Mathieu Desnoyers 
EfficiOS Inc. 
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