NAME | SYNOPSIS | DESCRIPTION | OPTIONS | PROBE SYNTAX | PROBE ARGUMENT | TYPES | LINE SYNTAX | LAZY MATCHING | FILTER PATTERN | EXAMPLES | SEE ALSO | COLOPHON

PERF-PROBE(1)                    perf Manual                   PERF-PROBE(1)

NAME         top

       perf-probe - Define new dynamic tracepoints

SYNOPSIS         top

       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
       or
       perf probe [options] --definition=PROBE [...]

DESCRIPTION         top

       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         top

       -k, --vmlinux=PATH
           Specify vmlinux path which has debuginfo (Dwarf binary). Only
           when using this with --definition, you can give an offline
           vmlinux file.

       -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.

       -D, --definition=
           Show trace-event definition converted from given probe-event
           instead of write it into tracing/[k,u]probe_events.

       --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         top

       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

       EVENT specifies the name of new event, if omitted, it will be set the
       name of the probed function. You can also specify a group name by
       GROUP, if omitted, set probe is used for kprobe and probe_<bin> is
       used for uprobe. Note that using existing group name can conflict
       with other events. Especially, using the group name reserved for
       kernel modules can hide embedded events in the modules. 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). SDTEVENT and
       PROVIDER is the pre-defined event name which is defined by user SDT
       (Statically Defined Tracing) or the pre-cached probes with event
       name. Note that before using the SDT event, the target binary (on
       which SDT events are defined) must be scanned by
       perf-buildid-cache(1) to make SDT events as cached events.

       For details of the SDT, see below.
       https://sourceware.org/gdb/onlinedocs/gdb/Static-Probe-Points.html 

PROBE ARGUMENT         top

       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.) $vars and $params special
       arguments are also available for NAME, $vars is expanded to the local
       variables (including function parameters) which can access at given
       probe point. $params is expanded to only the function parameters.
       TYPE casts the type of this argument (optional). If omitted, perf
       probe automatically set the type based on debuginfo (*). Currently,
       basic types (u8/u16/u32/u64/s8/s16/s32/s64), hexadecimal integers
       (x/x8/x16/x32/x64), signedness casting (u/s), "string" and bitfield
       are supported. (see TYPES for detail) On x86 systems %REG is always
       the short form of the register: for example %AX. %RAX or %EAX is not
       valid.

TYPES         top

       Basic types (u8/u16/u32/u64/s8/s16/s32/s64) and hexadecimal integers
       (x8/x16/x32/x64) are integer types. Prefix s and u means those types
       are signed and unsigned respectively, and x means that is shown in
       hexadecimal format. Traced arguments are shown in decimal (sNN/uNN)
       or hex (xNN). You can also use s or u to specify only signedness and
       leave its size auto-detected by perf probe. Moreover, you can use x
       to explicitly specify to be shown in hexadecimal (the size is also
       auto-detected). 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         top

       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         top

           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         top

           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         top

       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 ALSO         top

       perf-trace(1), perf-record(1), perf-buildid-cache(1)

COLOPHON         top

       This page is part of the perf (Performance analysis tools for Linux
       (in Linux source tree)) project.  Information about the project can
       be found at ⟨https://perf.wiki.kernel.org/index.php/Main_Page⟩.  If
       you have a bug report for this manual page, send it to
       linux-kernel@vger.kernel.org.  This page was obtained from the
       project's upstream Git repository 
       ⟨http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git⟩ on
       2017-03-13.  If you discover any rendering problems in this HTML ver‐
       sion of the page, or you believe there is a better or more up-to-date
       source for the page, or you have corrections or improvements to the
       information in this COLOPHON (which is not part of the original man‐
       ual page), send a mail to man-pages@man7.org

perf                             02/18/2017                    PERF-PROBE(1)