missing enable syscalls in create session
[lttngtop.git] / README-LIVE
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1As of LTTng v2.4, we can now process traces while they are being recorded
2(called live-tracing). LTTngtop can read live traces either in the ncurses GUI
3or in text mode.
4
5In order to use this feature, start by creating a live session with at least
6the events and contexts required for LTTngtop (see the manpage for that). A
7simple script to do the basic setup is available in
8utils/create-live-session.sh
9
10Once the session is created, you can list the sessions established on the
11relay with :
12$ lttngtop -r net://relaydhostname
13
14And attach to a session with
15$ lttngtop -r net://relaydhostname/host/<hostname/<session-name>
16
17A few seconds later, you should begin to see your live trace being displayed in
18lttngtop gui.
19To use the textdump feature, use the -t (and see --help for more options). You
20can also use the new lttngtrace provided by lttngtop which does all the setup
21for a live trace in textdump on localhost.
22
23
24EXPERIMENTAL :
25In order to use the (beta) MMAP live tracing features of LttngTop, you need these
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26branches :
27
28git clone -b lttngtop-live git://git.dorsal.polymtl.ca/~jdesfossez/lttng-tools
29git clone -b lttngtop-live git://git.dorsal.polymtl.ca/~jdesfossez/babeltrace
30
31The only difference between these branches and the master branch is that they
32export an additional library that is used by lttngtop to do live tracing.
33
34You have to compile and install lttng-tools before babeltrace since there are
35dependencies on the library exposed by this special lttng-tools in babeltrace
36for live mmap buffer consuming.
37
38Then you can compile and use the live branch of LttngTop :
39git clone -b live git://git.lttng.org/lttngtop.git
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40
41Once everything is installed, you can start as root lttng-sessiond and use
42lttngtop (as root or from a user part of the "tracing" group).
43
44Note: if lttng-sessiond has been used to record a trace before starting
45lttngtop (normal lttng use-case), you need to restart it because it
46automatically spawned a consumer that prevents lttngtop from registering its
47own consumer. The same applies when you finish using lttngtop, you need to
48restart the lttng-sessiond daemon to allow others to record traces again. This
49is a know problem of integration that will be fixed.
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