On 2025-06-05 06:49, David Aldrich wrote:
Hi Mathieu
I'd like to add some more detail. I now run our app using this pattern:
LD_PRELOAD=liblttng-ust-cyg-profile.so ./app
On importing the trace into TraceCompass I see:
"null analysis for LTTng-UST CallStack"
Could the reason be the lttng commands I am using to capture UST and
Kernel events:
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
Indeed, You will also need to enable something like this:
lttng enable-event --userspace 'lttng_ust_cyg_profile:*'
See "man 3 lttng-ust-cyg-profile" for details.
Thanks,
Mathieu
Best regards
David
On Wed, Jun 4, 2025 at 5:22 PM David Aldrich
<david.aldrich.n...@gmail.com> wrote:
Hi Mathieu
Any idea what I am doing wrong please?
AFAIK, the "LD_PRELOAD" environment variable is cleared by
sudo when running its child process for security purposes.
Thanks for your answer, that does help. However, I have now adjusted
the code so that sudo is not required, but when I import the trace the
UST-CallStacks are still strikethrough.
Any thoughts why this is happening?
I don't see any runtime errors whether or not I specify the prefix:
LD_PRELOAD=liblttng-ust-cyg-profile.so
Is that expected?
Best regards, David
--
Mathieu Desnoyers
EfficiOS Inc.
https://www.efficios.com
