1perf-probe(1)
2=============
3
4NAME
5----
6perf-probe - Define new dynamic tracepoints
7
8SYNOPSIS
9--------
10[verse]
11'perf probe' [options] --add='PROBE' [...]
12or
13'perf probe' [options] PROBE
14or
15'perf probe' [options] --del='[GROUP:]EVENT' [...]
16or
17'perf probe' --list
18or
19'perf probe' [options] --line='FUNC[:RLN[+NUM|:RLN2]]|SRC:ALN[+NUM|:ALN2]'
20or
21'perf probe' [options] --vars='PROBEPOINT'
22
23DESCRIPTION
24-----------
25This command defines dynamic tracepoint events, by symbol and registers
26without debuginfo, or by C expressions (C line numbers, C function names,
27and C local variables) with debuginfo.
28
29
30OPTIONS
31-------
32-k::
33--vmlinux=PATH::
34	Specify vmlinux path which has debuginfo (Dwarf binary).
35
36-m::
37--module=MODNAME::
38	Specify module name in which perf-probe searches probe points
39	or lines.
40
41-s::
42--source=PATH::
43	Specify path to kernel source.
44
45-v::
46--verbose::
47        Be more verbose (show parsed arguments, etc).
48
49-a::
50--add=::
51	Define a probe event (see PROBE SYNTAX for detail).
52
53-d::
54--del=::
55	Delete probe events. This accepts glob wildcards('*', '?') and character
56	classes(e.g. [a-z], [!A-Z]).
57
58-l::
59--list::
60	List up current probe events.
61
62-L::
63--line=::
64	Show source code lines which can be probed. This needs an argument
65	which specifies a range of the source code. (see LINE SYNTAX for detail)
66
67-V::
68--vars=::
69	Show available local variables at given probe point. The argument
70	syntax is same as PROBE SYNTAX, but NO ARGs.
71
72--externs::
73	(Only for --vars) Show external defined variables in addition to local
74	variables.
75
76-f::
77--force::
78	Forcibly add events with existing name.
79
80-n::
81--dry-run::
82	Dry run. With this option, --add and --del doesn't execute actual
83	adding and removal operations.
84
85--max-probes::
86	Set the maximum number of probe points for an event. Default is 128.
87
88PROBE SYNTAX
89------------
90Probe points are defined by following syntax.
91
92    1) Define event based on function name
93     [EVENT=]FUNC[@SRC][:RLN|+OFFS|%return|;PTN] [ARG ...]
94
95    2) Define event based on source file with line number
96     [EVENT=]SRC:ALN [ARG ...]
97
98    3) Define event based on source file with lazy pattern
99     [EVENT=]SRC;PTN [ARG ...]
100
101
102'EVENT' specifies the name of new event, if omitted, it will be set the name of the probed function. Currently, event group name is set as 'probe'.
103'FUNC' specifies a probed function name, and it may have one of the following options; '+OFFS' is the offset from function entry address in bytes, ':RLN' is the relative-line number from function entry line, and '%return' means that it probes function return. And ';PTN' means lazy matching pattern (see LAZY MATCHING). Note that ';PTN' must be the end of the probe point definition.  In addition, '@SRC' specifies a source file which has that function.
104It is also possible to specify a probe point by the source line number or lazy matching by using 'SRC:ALN' or 'SRC;PTN' syntax, where 'SRC' is the source file path, ':ALN' is the line number and ';PTN' is the lazy matching pattern.
105'ARG' specifies the arguments of this probe point, (see PROBE ARGUMENT).
106
107PROBE ARGUMENT
108--------------
109Each probe argument follows below syntax.
110
111 [NAME=]LOCALVAR|$retval|%REG|@SYMBOL[:TYPE]
112
113'NAME' specifies the name of this argument (optional). You can use the name of local variable, local data structure member (e.g. var->field, var.field2), local array with fixed index (e.g. array[1], var->array[0], var->pointer[2]), or kprobe-tracer argument format (e.g. $retval, %ax, etc). Note that the name of this argument will be set as the last member name if you specify a local data structure member (e.g. field2 for 'var->field1.field2'.)
114'TYPE' casts the type of this argument (optional). If omitted, perf probe automatically set the type based on debuginfo. You can specify 'string' type only for the local variable or structure member which is an array of or a pointer to 'char' or 'unsigned char' type.
115
116LINE SYNTAX
117-----------
118Line range is described by following syntax.
119
120 "FUNC[:RLN[+NUM|-RLN2]]|SRC[:ALN[+NUM|-ALN2]]"
121
122FUNC specifies the function name of showing lines. 'RLN' is the start line
123number from function entry line, and 'RLN2' is the end line number. As same as
124probe syntax, 'SRC' means the source file path, 'ALN' is start line number,
125and 'ALN2' is end line number in the file. It is also possible to specify how
126many lines to show by using 'NUM'.
127So, "source.c:100-120" shows lines between 100th to l20th in source.c file. And "func:10+20" shows 20 lines from 10th line of func function.
128
129LAZY MATCHING
130-------------
131 The lazy line matching is similar to glob matching but ignoring spaces in both of pattern and target. So this accepts wildcards('*', '?') and character classes(e.g. [a-z], [!A-Z]).
132
133e.g.
134 'a=*' can matches 'a=b', 'a = b', 'a == b' and so on.
135
136This provides some sort of flexibility and robustness to probe point definitions against minor code changes. For example, actual 10th line of schedule() can be moved easily by modifying schedule(), but the same line matching 'rq=cpu_rq*' may still exist in the function.)
137
138
139EXAMPLES
140--------
141Display which lines in schedule() can be probed:
142
143 ./perf probe --line schedule
144
145Add a probe on schedule() function 12th line with recording cpu local variable:
146
147 ./perf probe schedule:12 cpu
148 or
149 ./perf probe --add='schedule:12 cpu'
150
151 this will add one or more probes which has the name start with "schedule".
152
153 Add probes on lines in schedule() function which calls update_rq_clock().
154
155 ./perf probe 'schedule;update_rq_clock*'
156 or
157 ./perf probe --add='schedule;update_rq_clock*'
158
159Delete all probes on schedule().
160
161 ./perf probe --del='schedule*'
162
163
164SEE ALSO
165--------
166linkperf:perf-trace[1], linkperf:perf-record[1]
167