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lttngtoptrace — Live textual LTTng Trace Viewer


lttngtoptrace [OPTIONS] [EXECUTABLE]


Lttngtoptrace is a live textual LTTng trace viewer, it allows to easily (one command)
start a LTTng session and view the live events. The intent is to do something similar to
strace but less intrusive and more flexible:
- run a command and see it's kernel trace almost instantly without slowing it
down too much (buffered at most 1 second) in combination with the trace of
any other process or the whole system
- follow multiple processes and/or the whole system
- follow the children of all attached processes
- attach to processes by name and/or pid
- actual time taken by the system calls (with reminder of start timestamp)
- sched_switch events to know the context switches that occurred for the
process we are interested in
- current CPU (to see the migrations)
- highlight the trace of a selection of processes while tracing the whole
system to easily see the interactions
- arbitrary kprobe additions to see if a process hits a certain place in the

Only a subset of the LTTng events are enabled (the statedump, sched_switch,
sched_process_fork and all the system calls).

The events are displayed with additionnal context information than just the raw LTTng
trace (such as the current process name/PID/TID, the start/end time of the current system
call, the delay since the last displayed event (filtering aware)).


-f Follow threads associated with selected PIDs

-p Comma-separated list of PIDs to display (in addition to the eventual executed

-n Comma-separated list of procnames to display (in addition to the eventual executed

-a In textdump mode, display all events but write in bold the processes we are
interested in (-f and -p)

-k kprobes to insert (same format as lttng enable-event, can be repeated)

-o <filename>
In textdump, output the log in <filename>

Program to run and connect the tracer (can be combined with other options to see
the trace of other processes)


A working installation of LTTng >= 2.4, the appropriate rights for the user to create a
kernel trace and start daemons (sudo is tried in case the user is not root), Babeltrace =
1.2.4, LTTngTop = 0.3

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