On 11-02-22 01:45 AM, Amir wrote:
Hi,
I'm really new to UST and generating user-space traces for software
systems.
I followed the instruction provided at:
http://lttng.org/files/ust/manual/ust.html
Packages were successfully installed and I could generate a trace
following the provided example for markers.
Still I have a few questions for which I couldn’t find answers in the
manual.
- what are 'event categories' and 'channels'?
A channel is as it's name indicates a way to communicate with UST. In
the trace, each channel has N files allocated to it where N is the
number of cores you have. Each channel also has a certain amount of
memory allocated to to. I tend to only use the channel "UST" as it makes
my life easier, but then again, I am a very bad person who's been caught
doing unsavory things to programs for a long while and that says 640k
ought to be enough for anybody without signs of irony.
Perhaps someone more knowledgeable in UST can show me the error in my ways.
- is it possible to generate a method call trace using markers? would
it work just for C applications?
You mean like "
void trace_result( int n ) {
trace_mark( ust, myevent, "%d" ,n);
}" ?
Yes, it's what I do... look into tracepoints though, you're halfway
there with that.
- it seems like 'Appendix x' is missing, how would it be possible to
have some information about the formatting
I think Appendix X was a placeholder, not sure, I didn't write it ;) .
Thanks,
Amir
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