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' --line='FUNC[:RLN[+NUM|:RLN2]]|SRC:ALN[+NUM|:ALN2]' 20 21DESCRIPTION 22----------- 23This command defines dynamic tracepoint events, by symbol and registers 24without debuginfo, or by C expressions (C line numbers, C function names, 25and C local variables) with debuginfo. 26 27 28OPTIONS 29------- 30-k:: 31--vmlinux=PATH:: 32 Specify vmlinux path which has debuginfo (Dwarf binary). 33 34-s:: 35--source=PATH:: 36 Specify path to kernel source. 37 38-v:: 39--verbose:: 40 Be more verbose (show parsed arguments, etc). 41 42-a:: 43--add=:: 44 Define a probe event (see PROBE SYNTAX for detail). 45 46-d:: 47--del=:: 48 Delete probe events. This accepts glob wildcards('*', '?') and character 49 classes(e.g. [a-z], [!A-Z]). 50 51-l:: 52--list:: 53 List up current probe events. 54 55-L:: 56--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 detail) 59 60-f:: 61--force:: 62 Forcibly add events with existing name. 63 64-n:: 65--dry-run:: 66 Dry run. With this option, --add and --del doesn't execute actual 67 adding and removal operations. 68 69--max-probes:: 70 Set the maximum number of probe points for an event. Default is 128. 71 72PROBE SYNTAX 73------------ 74Probe points are defined by following syntax. 75 76 1) Define event based on function name 77 [EVENT=]FUNC[@SRC][:RLN|+OFFS|%return|;PTN] [ARG ...] 78 79 2) Define event based on source file with line number 80 [EVENT=]SRC:ALN [ARG ...] 81 82 3) Define event based on source file with lazy pattern 83 [EVENT=]SRC;PTN [ARG ...] 84 85 86'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'. 87'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. 88It 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. 89'ARG' specifies the arguments of this probe point, (see PROBE ARGUMENT). 90 91PROBE ARGUMENT 92-------------- 93Each probe argument follows below syntax. 94 95 [NAME=]LOCALVAR|$retval|%REG|@SYMBOL[:TYPE] 96 97'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'.) 98'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. 99 100LINE SYNTAX 101----------- 102Line range is descripted by following syntax. 103 104 "FUNC[:RLN[+NUM|-RLN2]]|SRC:ALN[+NUM|-ALN2]" 105 106FUNC specifies the function name of showing lines. 'RLN' is the start line 107number from function entry line, and 'RLN2' is the end line number. As same as 108probe syntax, 'SRC' means the source file path, 'ALN' is start line number, 109and 'ALN2' is end line number in the file. It is also possible to specify how 110many lines to show by using 'NUM'. 111So, "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. 112 113LAZY MATCHING 114------------- 115 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]). 116 117e.g. 118 'a=*' can matches 'a=b', 'a = b', 'a == b' and so on. 119 120This 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.) 121 122 123EXAMPLES 124-------- 125Display which lines in schedule() can be probed: 126 127 ./perf probe --line schedule 128 129Add a probe on schedule() function 12th line with recording cpu local variable: 130 131 ./perf probe schedule:12 cpu 132 or 133 ./perf probe --add='schedule:12 cpu' 134 135 this will add one or more probes which has the name start with "schedule". 136 137 Add probes on lines in schedule() function which calls update_rq_clock(). 138 139 ./perf probe 'schedule;update_rq_clock*' 140 or 141 ./perf probe --add='schedule;update_rq_clock*' 142 143Delete all probes on schedule(). 144 145 ./perf probe --del='schedule*' 146 147 148SEE ALSO 149-------- 150linkperf:perf-trace[1], linkperf:perf-record[1] 151