[lttng-dev] Filtering tracing by process name or PID/TID

Rengar Stinkt rengarop2611 at gmail.com
Wed Feb 15 04:09:47 EST 2023


Dear community,

I only recently started working with lttng tracing due to work related
projects, so I am very new to this. I have done some research before
posting this but I can't seem to find an answer.
I am running several CPU load tests for specific processes on different
devices using lttng and TraceCompass for visualization. I am running into
the issue that 99.9% of traced processes are not of value to me and the
tracing files get extremely big and hard to work with (filtering with
TraceCompass is very slow).
Now I thought of filtering the processes before tracing and I found
filtering by PID and TID. The issue with this is that the PIDs and TIDs are
unique on each device but change between devices.
I then found the command "htop -d 0.1 -u **String**" to see currently
running processes with a certain name.
Now if I run this it shows me the running process IF they are running. I
have time triggered and event triggered processes. There are many
inconvenient workarounds to make it work, like triggering the events and
finding out the PID and then manually copying all of the IDs and pasting
them into "lttng track --kernel --pid=""". But I am trying to find a way to
either filter by name right away, avoiding relying on PIDs or at least to
have an automated process of doing it. But I am unfamiliar with running
code in the PuTTY terminal that we are using, so I am trying to avoid this
(for now). If this is the only option though, I will have to look into it.
Is there any way to filter by name right away like in the mentioned htop
command?

Thank you so much in advance.
Dom
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