[lttng-dev] [lttng-ust] Missing events when just before a process exits

[THEUNISSEN Rolf]

Hi,

I am currently tracing many processes with LTTng-UST on a system under heavy load, with 2 CPUs.

The traces seem to be missing ust-events near the end of a trace. After doing some analysis, it seems that events are missing from the other CPU then the process exits on. More concretely:

During the lifetime of a process:
- Process X executes on CPU 0,1: all events are in the trace
Just before the process is about to exit:
- Process X executes on CPU 0: missing events from the trace
A few mili-seconds later:
- Process X executes on CPU1 and exits: The last events are in the trace

Is this behavior expected, or am I running into an LTTng-UST bug? And would there be any workaround?

Kind regards,
Rolf Theunissen