Hi everyone
I am experimenting with enabling trace for a specific iteration of a loop in my
application.
I created 2 trace points at the start and end of the loop which log the
iteration number.
the loop itself creates thousands of trace points. It runs for ~5ms.
on lttng side I created 2 triggers to start and stop my session in case the
loop tracepoint registers a specific iteration number.
the triggers seem to work since there is another session entry created under
the session folder but there are very few tracepoints.
is it possible that the delay between the event happening and the session trace
starting causes loss of events ?
If yes, is there a way around this ?
here is my setup :
#lttng-status
Recording session session: [inactive]
Trace output: /home/user/lttng-traces/session-20230523-113537
=== Domain: User space ===
Buffering scheme: per-user
Tracked process attributes
Virtual process IDs: all
Virtual user IDs: all
Virtual group IDs: all
Channels:
-------------
- user-channel: [enabled]
Attributes:
Event-loss mode: discard
Sub-buffer size: 16777216 bytes
Sub-buffer count: 128
Switch timer: inactive
Read timer: inactive
Monitor timer: 1000000 us
Blocking timeout: 0 us
Trace file count: 1 per stream
Trace file size: unlimited
Output mode: mmap
Statistics:
Discarded events: 0
Recording event rules:
trace_events* (type: tracepoint) [enabled]
loop* (type: tracepoint) [enabled]
#lttng list-triggers
- name: iter-start
owner uid: 1000
condition: event rule matches
rule: loop:iteration (type: user tracepoint, filter: iter==2 && start == 1)
errors: none
actions:
start session `session`
errors: none
errors: none
- name: iter-stop
owner uid: 1000
condition: event rule matches
rule: loop:iteration (type: user tracepoint, filter: iter==2 && start == 0)
errors: none
actions:
stop session `session`
errors: none
errors: none
Thanks
Yehuda
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