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='LINE' 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|PATH:: 38 Specify module name in which perf-probe searches probe points 39 or lines. If a path of module file is passed, perf-probe 40 treat it as an offline module (this means you can add a probe on 41 a module which has not been loaded yet). 42 43-s:: 44--source=PATH:: 45 Specify path to kernel source. 46 47-v:: 48--verbose:: 49 Be more verbose (show parsed arguments, etc). 50 51-a:: 52--add=:: 53 Define a probe event (see PROBE SYNTAX for detail). 54 55-d:: 56--del=:: 57 Delete probe events. This accepts glob wildcards('*', '?') and character 58 classes(e.g. [a-z], [!A-Z]). 59 60-l:: 61--list:: 62 List up current probe events. 63 64-L:: 65--line=:: 66 Show source code lines which can be probed. This needs an argument 67 which specifies a range of the source code. (see LINE SYNTAX for detail) 68 69-V:: 70--vars=:: 71 Show available local variables at given probe point. The argument 72 syntax is same as PROBE SYNTAX, but NO ARGs. 73 74--externs:: 75 (Only for --vars) Show external defined variables in addition to local 76 variables. 77 78-F:: 79--funcs:: 80 Show available functions in given module or kernel. With -x/--exec, 81 can also list functions in a user space executable / shared library. 82 83--filter=FILTER:: 84 (Only for --vars and --funcs) Set filter. FILTER is a combination of glob 85 pattern, see FILTER PATTERN for detail. 86 Default FILTER is "!__k???tab_* & !__crc_*" for --vars, and "!_*" 87 for --funcs. 88 If several filters are specified, only the last filter is used. 89 90-f:: 91--force:: 92 Forcibly add events with existing name. 93 94-n:: 95--dry-run:: 96 Dry run. With this option, --add and --del doesn't execute actual 97 adding and removal operations. 98 99--max-probes:: 100 Set the maximum number of probe points for an event. Default is 128. 101 102-x:: 103--exec=PATH:: 104 Specify path to the executable or shared library file for user 105 space tracing. Can also be used with --funcs option. 106 107In absence of -m/-x options, perf probe checks if the first argument after 108the options is an absolute path name. If its an absolute path, perf probe 109uses it as a target module/target user space binary to probe. 110 111PROBE SYNTAX 112------------ 113Probe points are defined by following syntax. 114 115 1) Define event based on function name 116 [EVENT=]FUNC[@SRC][:RLN|+OFFS|%return|;PTN] [ARG ...] 117 118 2) Define event based on source file with line number 119 [EVENT=]SRC:ALN [ARG ...] 120 121 3) Define event based on source file with lazy pattern 122 [EVENT=]SRC;PTN [ARG ...] 123 124 125'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'. 126'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. 127It 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. 128'ARG' specifies the arguments of this probe point, (see PROBE ARGUMENT). 129 130PROBE ARGUMENT 131-------------- 132Each probe argument follows below syntax. 133 134 [NAME=]LOCALVAR|$retval|%REG|@SYMBOL[:TYPE] 135 136'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'.) 137'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. 138 139On x86 systems %REG is always the short form of the register: for example %AX. %RAX or %EAX is not valid. 140 141LINE SYNTAX 142----------- 143Line range is described by following syntax. 144 145 "FUNC[@SRC][:RLN[+NUM|-RLN2]]|SRC[:ALN[+NUM|-ALN2]]" 146 147FUNC specifies the function name of showing lines. 'RLN' is the start line 148number from function entry line, and 'RLN2' is the end line number. As same as 149probe syntax, 'SRC' means the source file path, 'ALN' is start line number, 150and 'ALN2' is end line number in the file. It is also possible to specify how 151many lines to show by using 'NUM'. Moreover, 'FUNC@SRC' combination is good 152for searching a specific function when several functions share same name. 153So, "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. 154 155LAZY MATCHING 156------------- 157 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]). 158 159e.g. 160 'a=*' can matches 'a=b', 'a = b', 'a == b' and so on. 161 162This 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.) 163 164FILTER PATTERN 165-------------- 166 The filter pattern is a glob matching pattern(s) to filter variables. 167 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 "(" ")". 168 169e.g. 170 With --filter "foo* | bar*", perf probe -V shows variables which start with "foo" or "bar". 171 With --filter "!foo* & *bar", perf probe -V shows variables which don't start with "foo" and end with "bar", like "fizzbar". But "foobar" is filtered out. 172 173EXAMPLES 174-------- 175Display which lines in schedule() can be probed: 176 177 ./perf probe --line schedule 178 179Add a probe on schedule() function 12th line with recording cpu local variable: 180 181 ./perf probe schedule:12 cpu 182 or 183 ./perf probe --add='schedule:12 cpu' 184 185 this will add one or more probes which has the name start with "schedule". 186 187 Add probes on lines in schedule() function which calls update_rq_clock(). 188 189 ./perf probe 'schedule;update_rq_clock*' 190 or 191 ./perf probe --add='schedule;update_rq_clock*' 192 193Delete all probes on schedule(). 194 195 ./perf probe --del='schedule*' 196 197Add probes at zfree() function on /bin/zsh 198 199 ./perf probe -x /bin/zsh zfree or ./perf probe /bin/zsh zfree 200 201Add probes at malloc() function on libc 202 203 ./perf probe -x /lib/libc.so.6 malloc or ./perf probe /lib/libc.so.6 malloc 204 205SEE ALSO 206-------- 207linkperf:perf-trace[1], linkperf:perf-record[1] 208