+Like kernel tracing, you can start the session daemon by invoking the command
+"lttng-sessiond", or let the lttng command line tool do it for you.
+
+NOTE: You do *not* need root credentials in order to tracer user-space
+applications. However, if you run the session daemon under non-root user
+rights, only applications of that user will be traced.
+
+So, after instrumenting you applications with LTTng-ust 2.0
+(http://lttng.org/lttng2.0), upon startup, it will automatically register to
+the session daemon. If there is none running, it will simply wait on a seperate
+thread for a session daemon to appear and then register.
+
+Start your instrumented application at any time but at least before starting
+tracing :).
+
+List available registered applications:
+
+$ lttng list -u
+
+1) Create a tracing session. The .lttng directory will be created with a
+.lttngrc file in $HOME containing the session name (here 'mysession') you are
+working on.
+
+$ lttng create mysession
+
+If you have multiple sessions, you can change the current session by using:
+
+$ lttng set-session myothersession
+
+2) Enable all tracepoints for the global UST domain ("-u" alone).
+
+$ lttng enable-event -a -u
+
+or enable a single tracepoint event.
+
+$ lttng enable-event ust_tests_hello:tptest -u
+
+3) This is also a new feature which allows you to add context information to an
+event. For example, you can add the PID along with the event information:
+
+$ lttng add-context -t pid -e ust_tests_hello:tptest -u
+
+At this point, you will have to look at 'lttng add-context --help' for all
+possible context type.
+
+You can on the same line activate multiple context:
+
+$ lttng add-context -u -e ust_tests_hello:tptest -t pid -t nice -t tid
+
+4) Start tracing:
+
+$ lttng start
+
+Tracing is in progress at this point and traces will be written in the session
+directory.
+
+NOTE: It will start tracing for *all* domain(s).
+
+5) Stop tracing:
+
+$ lttng stop
+
+NOTE: At this point, you can restart the trace (lttng start), enable/disable
+events or just go take a break and come back 3 days later to start it again :).
+You can also read the trace since the buffers are flushed on stop command.
+
+6) Destroy your session after you are done with tracing
+
+$ lttng destroy
+
+See "Reading a trace" section below to read you trace(s).
+
projects / lttng-tools.git / blobdiff