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PERF_4.8-PROBE(1) | perf Manual | PERF_4.8-PROBE(1) |
NAME¶
perf-probe - Define new dynamic tracepointsSYNOPSIS¶
perf probe [options] --add=PROBE [...] or perf probe [options] PROBE or perf probe [options] --del=[GROUP:]EVENT [...] or perf probe --list[=[GROUP:]EVENT] or perf probe [options] --line=LINE or perf probe [options] --vars=PROBEPOINT or perf probe [options] --funcs
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=PATHSpecify 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). Can not use
with -q.
-q, --quiet
Be quiet (do not show any messages including errors). Can
not use with -v.
-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[=[GROUP:]EVENT]
List up current probe events. This can also accept
filtering patterns of event names. When this is used with --cache, perf shows
all cached probes instead of the live probes.
-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.
--no-inlines
(Only for --add) Search only for non-inlined functions.
The functions which do not have instances are ignored.
-F, --funcs[=FILTER]
Show available functions in given module or kernel. With
-x/--exec, can also list functions in a user space executable / shared
library. This also can accept a FILTER rule argument.
--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.
--cache
(With --add) Cache the probes. Any events which
successfully added are also stored in the cache file. (With --list) Show
cached probes. (With --del) Remove cached probes.
--max-probes=NUM
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.
--demangle
Demangle application symbols. --no-demangle is also
available for disabling demangling.
--demangle-kernel
Demangle kernel symbols. --no-demangle-kernel is also
available for disabling kernel demangling.
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 [[GROUP:]EVENT=]FUNC[@SRC][:RLN|+OFFS|%return|;PTN] [ARG ...]
2) Define event based on source file with line number [[GROUP:]EVENT=]SRC:ALN [ARG ...]
3) Define event based on source file with lazy pattern [[GROUP:]EVENT=]SRC;PTN [ARG ...]
4) Pre-defined SDT events or cached event with name %[sdt_PROVIDER:]SDTEVENT or, sdt_PROVIDER:SDTEVENT
PROBE ARGUMENT¶
Each probe argument follows below syntax.[NAME=]LOCALVAR|$retval|%REG|@SYMBOL[:TYPE]
TYPES¶
Basic types (u8/u16/u32/u64/s8/s16/s32/s64) are integer types. Prefix s and u means those types are signed and unsigned respectively. Traced arguments are shown in decimal (signed) or hex (unsigned). You can also use s or u to specify only signedness and leave its size auto-detected by perf probe. String type is a special type, which fetches a "null-terminated" string from kernel space. This means it will fail and store NULL if the string container has been paged out. 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. Bitfield is another special type, which takes 3 parameters, bit-width, bit-offset, and container-size (usually 32). The syntax is;b<bit-width>@<bit-offset>/<container-size>
LINE SYNTAX¶
Line range is described by following syntax."FUNC[@SRC][:RLN[+NUM|-RLN2]]|SRC[:ALN[+NUM|-ALN2]]"
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]).
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 "(" ")".
EXAMPLES¶
Display which lines in schedule() can be probed:./perf probe --line schedule
./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*'
./perf probe --del='schedule*'
./perf probe -x /bin/zsh zfree or ./perf probe /bin/zsh zfree
./perf probe -x /lib/libc.so.6 malloc or ./perf probe /lib/libc.so.6 malloc
SEE ALSO¶
perf_4.8-trace(1), perf_4.8-record(1), perf_4.8-buildid-cache(1)2017-01-17 | perf |