Function tracing not working

[David Aldrich via lttng-dev <lttng-dev@lists.lttng.org>]

Hi,

I am trying to use lttng-ust-cyg-profile.

Our application is large so, so far, I only compile main.cpp with
compiler option '-finstrument-functions' (I don't specify option
'-pg').

Our app must be run as root so I run it, and capture with lttng, like this:

lttng create app_trace
lttng enable-event --userspace 'lttng_ust_tracef:*'
lttng enable-channel --kernel --session app_trace kernel_channel
lttng enable-event --kernel --all --channel kernel_channel --session app_trace
export LD_PRELOAD=liblttng-ust-cyg-profile.so
lttng start
sudo -E ./myapp
lttng stop

I notice that many events get discarded:

Warning: 198522 events were discarded, please refer to the
documentation on channel configuration.

I then import into TraceCompass.  I see the traces in the Resources
View, but when I expand Experiment > Views, all 3 'LTTng-UST
CallStack' entries are striked through so I can't select them. So I
can't visualise the function calls.

Any idea what I am doing wrong please?

Best regards, David