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65226554 PP |
1 | lttng-track(1) |
2 | ============== | |
3 | ||
4 | ||
5 | NAME | |
6 | ---- | |
7 | lttng-track - Add one or more entries to an LTTng resource tracker | |
8 | ||
9 | ||
10 | SYNOPSIS | |
11 | -------- | |
12 | [verse] | |
13 | *lttng* ['GENERAL OPTIONS'] *track* (option:--kernel | option:--userspace) | |
14 | [option:--session='SESSION'] (option:--pid='PID'[,'PID']... | option:--all option:--pid) | |
15 | ||
16 | ||
17 | DESCRIPTION | |
18 | ----------- | |
19 | The `lttng track` commands adds one or more entries to a | |
20 | resource tracker. | |
21 | ||
22 | A resource tracker is a _whitelist_ of resources. Tracked resources are | |
23 | allowed to emit events, provided those events are targeted by enabled | |
24 | event rules (see linklttng:lttng-enable-event(1)). | |
25 | ||
26 | Tracker entries can be removed from the whitelist with | |
27 | linklttng:lttng-untrack(1). | |
28 | ||
29 | As of this version, the only available tracker is the *PID tracker*. The | |
30 | process ID (PID) tracker follows one or more process IDs; only the | |
31 | processes with a tracked PID are allowed to emit events. By default, all | |
32 | possible PIDs on the system are tracked: any process may emit enabled | |
33 | events (equivalent of `lttng track --pid --all` for all domains). | |
34 | ||
35 | With the PID tracker, it is possible, for example, to record all system | |
36 | calls called by a given process: | |
37 | ||
38 | ------------------------------------------- | |
39 | lttng enable-event --kernel --all --syscall | |
40 | lttng track --kernel --pid=2345 | |
41 | lttng start | |
42 | ------------------------------------------- | |
43 | ||
44 | If all the PIDs are tracked (i.e. `lttng track --pid --all`, which is | |
45 | the default state of all domains when creating a tracing session), then | |
46 | using the track command with one or more specific PIDs has the effect of | |
47 | first removing all the PIDs from the whitelist, then adding the | |
48 | specified PIDs. | |
49 | ||
50 | ||
51 | Example | |
52 | ~~~~~~~ | |
53 | Assume the maximum system PID is 7 for this example. | |
54 | ||
55 | Initial whitelist: | |
56 | ||
57 | ------------------------------- | |
58 | [0] [1] [2] [3] [4] [5] [6] [7] | |
59 | ------------------------------- | |
60 | ||
61 | Command: | |
62 | ||
63 | ----------------------------------- | |
64 | lttng track --userspace --pid=3,6,7 | |
65 | ----------------------------------- | |
66 | ||
67 | Whitelist: | |
68 | ||
69 | ------------------------------- | |
70 | [ ] [ ] [ ] [3] [ ] [ ] [6] [7] | |
71 | ------------------------------- | |
72 | ||
73 | Command: | |
74 | ||
75 | --------------------------------- | |
76 | lttng untrack --userspace --pid=7 | |
77 | --------------------------------- | |
78 | ||
79 | Whitelist: | |
80 | ||
81 | ------------------------------- | |
82 | [ ] [ ] [ ] [3] [ ] [ ] [6] [ ] | |
83 | ------------------------------- | |
84 | ||
85 | Command: | |
86 | ||
87 | --------------------------------- | |
88 | lttng track --userspace --pid=1,5 | |
89 | --------------------------------- | |
90 | ||
91 | Whitelist: | |
92 | ||
93 | ------------------------------- | |
94 | [ ] [1] [ ] [3] [ ] [5] [6] [ ] | |
95 | ------------------------------- | |
96 | ||
97 | It should be noted that the PID tracker tracks the numeric process IDs. | |
98 | Should a process with a given ID exit and another process be given this | |
99 | ID, then the latter would also be allowed to emit events. | |
100 | ||
101 | See the linklttng:lttng-untrack(1) for more details about removing | |
102 | entries. | |
103 | ||
104 | ||
105 | include::common-cmd-options-head.txt[] | |
106 | ||
107 | ||
108 | Domain | |
109 | ~~~~~~ | |
110 | One of: | |
111 | ||
112 | option:-k, option:--kernel:: | |
113 | Track resources in the Linux kernel domain. | |
114 | ||
115 | option:-u, option:--userspace:: | |
116 | Track resources in the user space domain. | |
117 | ||
118 | ||
119 | Target | |
120 | ~~~~~~ | |
121 | option:-s, option:--session='SESSION':: | |
122 | Track resources in the tracing session named 'SESSION' instead of | |
123 | the current tracing session. | |
124 | ||
125 | ||
126 | Tracking | |
127 | ~~~~~~~~ | |
128 | option:-a, option:--all:: | |
129 | Used in conjunction with an empty option:--pid option: track _all_ | |
130 | process IDs (add all entries to the whitelist). | |
131 | ||
132 | option:-p, option:--pid[='PID'[,'PID']...]:: | |
133 | Track process IDs 'PID' (add them to the current whitelist). | |
134 | + | |
135 | The 'PID' argument must be omitted when also using the option:--all | |
136 | option. | |
137 | ||
138 | ||
139 | include::common-cmd-help-options.txt[] | |
140 | ||
141 | ||
142 | include::common-cmd-footer.txt[] | |
143 | ||
144 | ||
145 | SEE ALSO | |
146 | -------- | |
147 | linklttng:lttng-untrack(1), | |
148 | linklttng:lttng(1) |