1PERF-PROBE(1) perf Manual PERF-PROBE(1)
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6 perf-probe - Define new dynamic tracepoints
7
9 perf probe [options] --add=PROBE [...]
10 or
11 perf probe [options] PROBE
12 or
13 perf probe [options] --del=[GROUP:]EVENT [...]
14 or
15 perf probe --list
16 or
17 perf probe [options] --line=LINE
18 or
19 perf probe [options] --vars=PROBEPOINT
20
22 This command defines dynamic tracepoint events, by symbol and registers
23 without debuginfo, or by C expressions (C line numbers, C function
24 names, and C local variables) with debuginfo.
25
27 -k, --vmlinux=PATH
28 Specify vmlinux path which has debuginfo (Dwarf binary).
29 -m, --module=MODNAME|PATH
31 Specify module name in which perf-probe searches probe points or
32 lines. If a path of module file is passed, perf-probe treat it as
33 an offline module (this means you can add a probe on a module which
34 has not been loaded yet).
35 -s, --source=PATH
37 Specify path to kernel source.
38 -v, --verbose
40 Be more verbose (show parsed arguments, etc). Can not use with -q.
41 -q, --quiet
43 Be quiet (do not show any messages including errors). Can not use
44 with -v.
45 -a, --add=
47 Define a probe event (see PROBE SYNTAX for detail).
48 -d, --del=
50 Delete probe events. This accepts glob wildcards(*, ?) and
51 character classes(e.g. [a-z], [!A-Z]).
52 -l, --list
54 List up current probe events.
55 -L, --line=
57 Show source code lines which can be probed. This needs an argument
58 which specifies a range of the source code. (see LINE SYNTAX for
59 detail)
60 -V, --vars=
62 Show available local variables at given probe point. The argument
63 syntax is same as PROBE SYNTAX, but NO ARGs.
64 --externs
66 (Only for --vars) Show external defined variables in addition to
67 local variables.
68 -F, --funcs
70 Show available functions in given module or kernel. With -x/--exec,
71 can also list functions in a user space executable / shared
72 library.
73 --filter=FILTER
75 (Only for --vars and --funcs) Set filter. FILTER is a combination
76 of glob pattern, see FILTER PATTERN for detail. Default FILTER is
77 "!k???tab_* & !crc_*" for --vars, and "!_*" for --funcs. If several
78 filters are specified, only the last filter is used.
79 -f, --force
81 Forcibly add events with existing name.
82 -n, --dry-run
84 Dry run. With this option, --add and --del doesn’t execute actual
85 adding and removal operations.
86 --max-probes=NUM
88 Set the maximum number of probe points for an event. Default is
89 128.
90 -x, --exec=PATH
92 Specify path to the executable or shared library file for user
93 space tracing. Can also be used with --funcs option. (this feature
94 is unsupported in RHEL6)
95 --demangle
97 Demangle application symbols. --no-demangle is also available for
98 disabling demangling.
99 --demangle-kernel
101 Demangle kernel symbols. --no-demangle-kernel is also available for
102 disabling kernel demangling.
103 In absence of -m/-x options, perf probe checks if the first argument
105 after the options is an absolute path name. If its an absolute path,
106 perf probe uses it as a target module/target user space binary to
107 probe.
108
110 Probe points are defined by following syntax.
111 1) Define event based on function name
113 [EVENT=]FUNC[@SRC][:RLN|+OFFS|%return|;PTN] [ARG ...]
114 2) Define event based on source file with line number
116 [EVENT=]SRC:ALN [ARG ...]
117 3) Define event based on source file with lazy pattern
119 [EVENT=]SRC;PTN [ARG ...]
120 EVENT specifies the name of new event, if omitted, it will be set the
122 name of the probed function. Currently, event group name is set as
123 probe. FUNC specifies a probed function name, and it may have one of
124 the following options; +OFFS is the offset from function entry address
125 in bytes, :RLN is the relative-line number from function entry line,
126 and %return means that it probes function return. And ;PTN means lazy
127 matching pattern (see LAZY MATCHING). Note that ;PTN must be the end of
128 the probe point definition. In addition, @SRC specifies a source file
129 which has that function. It is also possible to specify a probe point
130 by the source line number or lazy matching by using SRC:ALN or SRC;PTN
131 syntax, where SRC is the source file path, :ALN is the line number and
132 ;PTN is the lazy matching pattern. ARG specifies the arguments of this
133 probe point, (see PROBE ARGUMENT).
134
136 Each probe argument follows below syntax.
137 [NAME=]LOCALVAR|$retval|%REG|@SYMBOL[:TYPE]
139 NAME specifies the name of this argument (optional). You can use the
141 name of local variable, local data structure member (e.g. var→field,
142 var.field2), local array with fixed index (e.g. array[1], var→array[0],
143 var→pointer[2]), or kprobe-tracer argument format (e.g. $retval, %ax,
144 etc). Note that the name of this argument will be set as the last
145 member name if you specify a local data structure member (e.g. field2
146 for var→field1.field2.) $vars special argument is also available for
147 NAME, it is expanded to the local variables which can access at given
148 probe point. TYPE casts the type of this argument (optional). If
149 omitted, perf probe automatically set the type based on debuginfo. You
150 can specify string type only for the local variable or structure member
151 which is an array of or a pointer to char or unsigned char type.
152 On x86 systems %REG is always the short form of the register: for
154 example %AX. %RAX or %EAX is not valid.
155
157 Line range is described by following syntax.
158 "FUNC[@SRC][:RLN[+NUM|-RLN2]]|SRC[:ALN[+NUM|-ALN2]]"
160 FUNC specifies the function name of showing lines. RLN is the start
162 line number from function entry line, and RLN2 is the end line number.
163 As same as probe syntax, SRC means the source file path, ALN is start
164 line number, and ALN2 is end line number in the file. It is also
165 possible to specify how many lines to show by using NUM. Moreover,
166 FUNC@SRC combination is good for searching a specific function when
167 several functions share same name. So, "source.c:100-120" shows lines
168 between 100th to l20th in source.c file. And "func:10+20" shows 20
169 lines from 10th line of func function.
170
172 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]).
173 e.g. a=* can matches a=b, a = b, a == b and so on.
175 This provides some sort of flexibility and robustness to probe point
177 definitions against minor code changes. For example, actual 10th line
178 of schedule() can be moved easily by modifying schedule(), but the same
179 line matching rq=cpu_rq* may still exist in the function.)
180
182 The filter pattern is a glob matching pattern(s) to filter variables.
183 In addition, you can use "!" for specifying filter-out rule. You also can give several rules combined with "&" or "|", and fold those rules as one rule by using "(" ")".
184 e.g. With --filter "foo* | bar*", perf probe -V shows variables which
186 start with "foo" or "bar". With --filter "!foo* & *bar", perf probe -V
187 shows variables which don’t start with "foo" and end with "bar", like
188 "fizzbar". But "foobar" is filtered out.
189
191 Display which lines in schedule() can be probed:
192 ./perf probe --line schedule
194 Add a probe on schedule() function 12th line with recording cpu local
196 variable:
197 ./perf probe schedule:12 cpu
199 or
200 ./perf probe --add=´schedule:12 cpu´
201 this will add one or more probes which has the name start with "schedule".
203 Add probes on lines in schedule() function which calls update_rq_clock().
205 ./perf probe ´schedule;update_rq_clock*´
207 or
208 ./perf probe --add=´schedule;update_rq_clock*´
209 Delete all probes on schedule().
211 ./perf probe --del=´schedule*´
213 Add probes at zfree() function on /bin/zsh
215 ./perf probe -x /bin/zsh zfree or ./perf probe /bin/zsh zfree
217 Add probes at malloc() function on libc
219 ./perf probe -x /lib/libc.so.6 malloc or ./perf probe /lib/libc.so.6 malloc
221
223 perf-trace(1), perf-record(1)
224perf 06/18/2019 PERF-PROBE(1)