PERF-PROBE(1) perf Manual PERF-PROBE(1)NAMEperf-probe - Define new dynamic tracepoints
SYNOPSIS
perf probe [options] --add=PROBE [...]
or
perf probe [options] PROBE
or
perf probe [options] --del=[GROUP:]EVENT [...]
or
perf probe --list
or
perf probe [options] --line=LINE
or
perf probe [options] --vars=PROBEPOINT
DESCRIPTION
This command defines dynamic tracepoint events, by symbol and registers
without debuginfo, or by C expressions (C line numbers, C function
names, and C local variables) with debuginfo.
OPTIONS-k, --vmlinux=PATH
Specify vmlinux path which has debuginfo (Dwarf binary).
-m, --module=MODNAME|PATH
Specify module name in which perf-probe searches probe points or
lines. If a path of module file is passed, perf-probe treat it as
an offline module (this means you can add a probe on a module which
has not been loaded yet).
-s, --source=PATH
Specify path to kernel source.
-v, --verbose
Be more verbose (show parsed arguments, etc).
-a, --add=
Define a probe event (see PROBE SYNTAX for detail).
-d, --del=
Delete probe events. This accepts glob wildcards(*, ?) and
character classes(e.g. [a-z], [!A-Z]).
-l, --list
List up current probe events.
-L, --line=
Show source code lines which can be probed. This needs an argument
which specifies a range of the source code. (see LINE SYNTAX for
detail)
-V, --vars=
Show available local variables at given probe point. The argument
syntax is same as PROBE SYNTAX, but NO ARGs.
--externs
(Only for --vars) Show external defined variables in addition to
local variables.
-F, --funcs
Show available functions in given module or kernel. With -x/--exec,
can also list functions in a user space executable / shared
library.
--filter=FILTER
(Only for --vars and --funcs) Set filter. FILTER is a combination
of glob pattern, see FILTER PATTERN for detail. Default FILTER is
"!k???tab_* & !crc_*" for --vars, and "!_*" for --funcs. If several
filters are specified, only the last filter is used.
-f, --force
Forcibly add events with existing name.
-n, --dry-run
Dry run. With this option, --add and --del doesn’t execute actual
adding and removal operations.
--max-probes
Set the maximum number of probe points for an event. Default is
128.
-x, --exec=PATH
Specify path to the executable or shared library file for user
space tracing. Can also be used with --funcs option.
In absence of -m/-x options, perf probe checks if the first argument
after the options is an absolute path name. If its an absolute path,
perf probe uses it as a target module/target user space binary to
probe.
PROBE SYNTAX
Probe points are defined by following syntax.
1) Define event based on function name
[EVENT=]FUNC[@SRC][:RLN|+OFFS|%return|;PTN] [ARG ...]
2) Define event based on source file with line number
[EVENT=]SRC:ALN [ARG ...]
3) Define event based on source file with lazy pattern
[EVENT=]SRC;PTN [ARG ...]
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. 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. It 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. ARG specifies the arguments of this
probe point, (see PROBE ARGUMENT).
PROBE ARGUMENT
Each probe argument follows below syntax.
[NAME=]LOCALVAR|$retval|%REG|@SYMBOL[:TYPE]
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.) 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.
LINE SYNTAX
Line range is described by following syntax.
"FUNC[@SRC][:RLN[+NUM|-RLN2]]|SRC[:ALN[+NUM|-ALN2]]"
FUNC specifies the function name of showing lines. RLN is the start
line number from function entry line, and RLN2 is the end line number.
As same as probe syntax, SRC means the source file path, ALN is start
line number, and ALN2 is end line number in the file. It is also
possible to specify how many lines to show by using NUM. Moreover,
FUNC@SRC combination is good for searching a specific function when
several functions share same name. So, "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.
LAZY MATCHING
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]).
e.g. a=* can matches a=b, a = b, a == b and so on.
This 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.)
FILTER PATTERN
The filter pattern is a glob matching pattern(s) to filter variables.
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 "(" ")".
e.g. With --filter "foo* | bar*", perf probe -V shows variables which
start with "foo" or "bar". 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.
EXAMPLES
Display which lines in schedule() can be probed:
./perf probe --line schedule
Add a probe on schedule() function 12th line with recording cpu local
variable:
./perf probe schedule:12 cpu
or
./perf probe --add='schedule:12 cpu'
this will add one or more probes which has the name start with "schedule".
Add probes on lines in schedule() function which calls update_rq_clock().
./perf probe 'schedule;update_rq_clock*'
or
./perf probe --add='schedule;update_rq_clock*'
Delete all probes on schedule().
./perf probe --del='schedule*'
Add probes at zfree() function on /bin/zsh
./perf probe -x /bin/zsh zfree or ./perf probe /bin/zsh zfree
Add probes at malloc() function on libc
./perf probe -x /lib/libc.so.6 malloc or ./perf probe /lib/libc.so.6 malloc
SEE ALSOperf-trace(1), perf-record(1)perf 3.6.11-4.fc16.x8 01/08/2013 PERF-PROBE(1)
