GSoC Project | Basic Support for Trace Compass

[Ravindra Kumar Meena]

Hi Sebastian,

I am in regular touch with Babeltrace community to figure out the solution
for conversion of trace data into CTF. I came to the conclusion that
current version 1.5.6 of Babeltrace does not have a feature to convert live
trace stream into CTF(we already had a discussion about it). However, this
feature is currently available in Babeltrace 2.0(master branch) but it is
currently in pre-stage.

The approach they shared is that after post-processing phase to convert
traces from some existing format to CTF we have to create a Babeltrace 2
source plugin which reads our trace format into the Babeltrace 2
intermediate representation by using the APIs exposed to plugins by
Babeltrace 2. Babeltrace 2 has a generic CTF sink which can serialize the
resulting trace intermediate representation into CTF.

The conversation I had between them in May is:
https://lists.lttng.org/pipermail/lttng-dev/2019-May/028944.html

and this months conversation is:
https://lists.lttng.org/pipermail/lttng-dev/2019-June/029022.html

Please have a look at the above thread. The community is very helpful they
have even shared a decoder(source plugin) example(you can see them in the
thread itself) which is necessary for whatever is produced as trace output
to convert into CTF. I will have a look at it.

I also came to know that Trace Compass does not support live traces. It is
made for post-mortem analyses, so it works only on complete trace. They
briefly supported live traces a few years back, but that made the code much
more complicated, so this support was dropped. TraceCompass is not made for
trace monitoring!

You can view the whole conversation here(I did this during application
period): https://lists.lttng.org/pipermail/lttng-dev/2019-March/028677.html

So, in my point of view, we should stick with the post-processing method.
We should store the traces in the disk and then convert it to CTF.

Thanks

-- 
*Ravindra Kumar Meena*,
B. Tech. Computer Science and Engineering,
Indian Institute of Technology (Indian School of Mines)
<https://www.iitism.ac.in/>, Dhanbad
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