perf-record(1)
NAME
perf-record - Run a command and record its profile into perf.data
SYNOPSIS
perf record [-e <EVENT> | --event=EVENT] [-l] [-a] <command> perf record [-e <EVENT> | --event=EVENT] [-l] [-a] --- <command> [<options>]
DESCRIPTION
This command runs a command and gathers a performance counter profile from it, into perf.data - without displaying anything. This file can then be inspected later on, using perf report.
OPTIONS
<command>...
Any command you can specify in a shell.
-e, --event=
Select the PMU event. Selection can be:
* a symbolic event name (use perf list to list all events)
* a raw PMU event (eventsel+umask) in the form of rNNN where NNN
is a hexadecimal event descriptor.
* a symbolically formed PMU event like pmu/param1=0x3,param2/
where param1, param2, etc are defined as formats for the PMU in
/sys/bus/event_source/devices/<pmu>/format/*.
* a symbolically formed event like
pmu/config=M,config1=N,config3=K/
where M, N, K are numbers (in decimal, hex, octal format). Acceptable
values for each of 'config', 'config1' and 'config2' are defined by
corresponding entries in /sys/bus/event_source/devices/<pmu>/format/*
param1 and param2 are defined as formats for the PMU in:
/sys/bus/event_source/devices/<pmu>/format/*
There are also some params which are not defined in .../<pmu>/format/*.
These params can be used to overload default config values per event.
Here is a list of the params.
- 'period': Set event sampling period
- 'freq': Set event sampling frequency
- 'time': Disable/enable time stamping. Acceptable values are 1 for
enabling time stamping. 0 for disabling time stamping.
The default is 1.
- 'call-graph': Disable/enable callgraph. Acceptable str are "fp" for
FP mode, "dwarf" for DWARF mode, "lbr" for LBR mode and
"no" for disable callgraph.
- 'stack-size': user stack size for dwarf mode
Note: If user explicitly sets options which conflict with the params,
the value set by the params will be overridden.
Also not defined in .../<pmu>/format/* are PMU driver specific
configuration parameters. Any configuration parameter preceded by
the letter '@' is not interpreted in user space and sent down directly
to the PMU driver. For example:
perf record -e some_event/@cfg1,@cfg2=config/ ...
will see 'cfg1' and 'cfg2=config' pushed to the PMU driver associated
with the event for further processing. There is no restriction on
what the configuration parameters are, as long as their semantic is
understood and supported by the PMU driver.
* a hardware breakpoint event in the form of
\mem:addr[/len][:access] where addr is the address in memory
you want to break in. Access is the memory access type (read,
write, execute) it can be passed as follows:
\mem:addr[:[r][w][x]]. len is the range, number of bytes from
specified addr, which the breakpoint will cover. If you want to
profile read-write accesses in 0x1000, just set mem:0x1000:rw.
If you want to profile write accesses in [0x1000~1008), just
set mem:0x1000/8:w.
* a group of events surrounded by a pair of brace
("{event1,event2,...}"). Each event is separated by commas and
the group should be quoted to prevent the shell interpretation.
You also need to use --group on "perf report" to view group
events together.
--filter=<filter>
Event filter. This option should follow a event selector (-e) which
selects either tracepoint event(s) or a hardware trace PMU (e.g.
Intel PT or CoreSight).
* tracepoint filters
In the case of tracepoints, multiple '--filter' options are combined
using '&&'.
* address filters
A hardware trace PMU advertises its ability to accept a number of
address filters by specifying a non-zero value in
/sys/bus/event_source/devices/<pmu>/nr_addr_filters.
Address filters have the format:
filter|start|stop|tracestop <start> [/ <size>] [@<file name>]
Where:
- 'filter': defines a region that will be traced.
- 'start': defines an address at which tracing will begin.
- 'stop': defines an address at which tracing will stop.
- 'tracestop': defines a region in which tracing will stop.
<file name> is the name of the object file, <start> is the offset to the
code to trace in that file, and <size> is the size of the region to
trace. 'start' and 'stop' filters need not specify a <size>.
If no object file is specified then the kernel is assumed, in which case
the start address must be a current kernel memory address.
<start> can also be specified by providing the name of a symbol. If the
symbol name is not unique, it can be disambiguated by inserting #n where
'n' selects the n'th symbol in address order. Alternately #0, #g or #G
select only a global symbol. <size> can also be specified by providing
the name of a symbol, in which case the size is calculated to the end
of that symbol. For 'filter' and 'tracestop' filters, if <size> is
omitted and <start> is a symbol, then the size is calculated to the end
of that symbol.
If <size> is omitted and <start> is '*', then the start and size will
be calculated from the first and last symbols, i.e. to trace the whole
file.
If symbol names (or '*') are provided, they must be surrounded by white
space.
The filter passed to the kernel is not necessarily the same as entered.
To see the filter that is passed, use the -v option.
The kernel may not be able to configure a trace region if it is not
within a single mapping. MMAP events (or /proc/<pid>/maps) can be
examined to determine if that is a possibility.
Multiple filters can be separated with space or comma.
--exclude-perf
Don't record events issued by perf itself. This option should
follow a event selector (-e) which selects tracepoint event(s). It
adds a filter expression common_pid != $PERFPID to filters. If
other --filter exists, the new filter expression will be combined
with them by &&.
-a, --all-cpus
System-wide collection from all CPUs.
-p, --pid=
Record events on existing process ID (comma separated list).
-t, --tid=
Record events on existing thread ID (comma separated list). This
option also disables inheritance by default. Enable it by adding
--inherit.
-u, --uid=
Record events in threads owned by uid. Name or number.
-r, --realtime=
Collect data with this RT SCHED_FIFO priority.
--no-buffering
Collect data without buffering.
-c, --count=
Event period to sample.
-o, --output=
Output file name.
-i, --no-inherit
Child tasks do not inherit counters.
-F, --freq=
Profile at this frequency.
-m, --mmap-pages=
Number of mmap data pages (must be a power of two) or size
specification with appended unit character - B/K/M/G. The size is
rounded up to have nearest pages power of two value. Also, by
adding a comma, the number of mmap pages for AUX area tracing can
be specified.
--group
Put all events in a single event group. This precedes the --event
option and remains only for backward compatibility. See --event.
-g
Enables call-graph (stack chain/backtrace) recording.
--call-graph
Setup and enable call-graph (stack chain/backtrace) recording,
implies -g. Default is "fp".
Allows specifying "fp" (frame pointer) or "dwarf"
(DWARF's CFI - Call Frame Information) or "lbr"
(Hardware Last Branch Record facility) as the method to collect
the information used to show the call graphs.
In some systems, where binaries are build with gcc
--fomit-frame-pointer, using the "fp" method will produce bogus
call graphs, using "dwarf", if available (perf tools linked to
the libunwind or libdw library) should be used instead.
Using the "lbr" method doesn't require any compiler options. It
will produce call graphs from the hardware LBR registers. The
main limition is that it is only available on new Intel
platforms, such as Haswell. It can only get user call chain. It
doesn't work with branch stack sampling at the same time.
When "dwarf" recording is used, perf also records (user) stack dump
when sampled. Default size of the stack dump is 8192 (bytes).
User can change the size by passing the size after comma like
"--call-graph dwarf,4096".
-q, --quiet
Don't print any message, useful for scripting.
-v, --verbose
Be more verbose (show counter open errors, etc).
-s, --stat
Record per-thread event counts. Use it with perf report -T to see
the values.
-d, --data
Record the sample addresses.
-T, --timestamp
Record the sample timestamps. Use it with perf report -D to see the
timestamps, for instance.
-P, --period
Record the sample period.
--sample-cpu
Record the sample cpu.
-n, --no-samples
Don't sample.
-R, --raw-samples
Collect raw sample records from all opened counters (default for
tracepoint counters).
-C, --cpu
Collect samples only on the list of CPUs provided. Multiple CPUs
can be provided as a comma-separated list with no space: 0,1.
Ranges of CPUs are specified with -: 0-2. In per-thread mode with
inheritance mode on (default), samples are captured only when the
thread executes on the designated CPUs. Default is to monitor all
CPUs.
-B, --no-buildid
Do not save the build ids of binaries in the perf.data files. This
skips post processing after recording, which sometimes makes the
final step in the recording process to take a long time, as it
needs to process all events looking for mmap records. The downside
is that it can misresolve symbols if the workload binaries used
when recording get locally rebuilt or upgraded, because the only
key available in this case is the pathname. You can also set the
"record.build-id" config variable to 'skip to have this behaviour
permanently.
-N, --no-buildid-cache
Do not update the buildid cache. This saves some overhead in
situations where the information in the perf.data file (which
includes buildids) is sufficient. You can also set the
"record.build-id" config variable to no-cache to have the same
effect.
-G name,..., --cgroup name,...
monitor only in the container (cgroup) called "name". This option
is available only in per-cpu mode. The cgroup filesystem must be
mounted. All threads belonging to container "name" are monitored
when they run on the monitored CPUs. Multiple cgroups can be
provided. Each cgroup is applied to the corresponding event, i.e.,
first cgroup to first event, second cgroup to second event and so
on. It is possible to provide an empty cgroup (monitor all the
time) using, e.g., -G foo,,bar. Cgroups must have corresponding
events, i.e., they always refer to events defined earlier on the
command line.
-b, --branch-any
Enable taken branch stack sampling. Any type of taken branch may be
sampled. This is a shortcut for --branch-filter any. See
--branch-filter for more infos.
-j, --branch-filter
Enable taken branch stack sampling. Each sample captures a series
of consecutive taken branches. The number of branches captured with
each sample depends on the underlying hardware, the type of
branches of interest, and the executed code. It is possible to
select the types of branches captured by enabling filters. The
following filters are defined:
* any: any type of branches
* any_call: any function call or system call
* any_ret: any function return or system call return
* ind_call: any indirect branch
* call: direct calls, including far (to/from kernel) calls
* u: only when the branch target is at the user level
* k: only when the branch target is in the kernel
* hv: only when the target is at the hypervisor level
* in_tx: only when the target is in a hardware transaction
* no_tx: only when the target is not in a hardware transaction
* abort_tx: only when the target is a hardware transaction abort
* cond: conditional branches
The option requires at least one branch type among any, any_call,
any_ret, ind_call, cond. The privilege levels may be omitted, in
which case, the privilege levels of the associated event are
applied to the branch filter. Both kernel (k) and hypervisor (hv)
privilege levels are subject to permissions. When sampling on
multiple events, branch stack sampling is enabled for all the
sampling events. The sampled branch type is the same for all
events. The various filters must be specified as a comma separated
list: --branch-filter any_ret,u,k Note that this feature may not be
available on all processors.
--weight
Enable weightened sampling. An additional weight is recorded per
sample and can be displayed with the weight and local_weight sort
keys. This currently works for TSX abort events and some memory
events in precise mode on modern Intel CPUs.
--transaction
Record transaction flags for transaction related events.
--per-thread
Use per-thread mmaps. By default per-cpu mmaps are created. This
option overrides that and uses per-thread mmaps. A side-effect of
that is that inheritance is automatically disabled. --per-thread is
ignored with a warning if combined with -a or -C options.
-D, --delay=
After starting the program, wait msecs before measuring. This is
useful to filter out the startup phase of the program, which is
often very different.
-I, --intr-regs
Capture machine state (registers) at interrupt, i.e., on counter
overflows for each sample. List of captured registers depends on
the architecture. This option is off by default. It is possible to
select the registers to sample using their symbolic names, e.g. on
x86, ax, si. To list the available registers use --intr-regs=\?. To
name registers, pass a comma separated list such as
--intr-regs=ax,bx. The list of register is architecture dependent.
--running-time
Record running and enabled time for read events (:S)
-k, --clockid
Sets the clock id to use for the various time fields in the
perf_event_type records. See clock_gettime(). In particular
CLOCK_MONOTONIC and CLOCK_MONOTONIC_RAW are supported, some events
might also allow CLOCK_BOOTTIME, CLOCK_REALTIME and CLOCK_TAI.
-S, --snapshot
Select AUX area tracing Snapshot Mode. This option is valid only
with an AUX area tracing event. Optionally the number of bytes to
capture per snapshot can be specified. In Snapshot Mode, trace data
is captured only when signal SIGUSR2 is received.
--proc-map-timeout
When processing pre-existing threads /proc/XXX/mmap, it may take a
long time, because the file may be huge. A time out is needed in
such cases. This option sets the time out limit. The default value
is 500 ms.
--switch-events
Record context switch events i.e. events of type PERF_RECORD_SWITCH
or PERF_RECORD_SWITCH_CPU_WIDE.
--clang-path=PATH
Path to clang binary to use for compiling BPF scriptlets. (enabled
when BPF support is on)
--clang-opt=OPTIONS
Options passed to clang when compiling BPF scriptlets. (enabled
when BPF support is on)
--vmlinux=PATH
Specify vmlinux path which has debuginfo. (enabled when BPF
prologue is on)
--buildid-all
Record build-id of all DSOs regardless whether it's actually hit or
not.
--all-kernel
Configure all used events to run in kernel space.
--all-user
Configure all used events to run in user space.
--timestamp-filename Append timestamp to output file name.
--switch-output
Generate multiple perf.data files, timestamp prefixed, switching to
a new one when receiving a SIGUSR2.
A possible use case is to, given an external event, slice the perf.data
file that gets then processed, possibly via a perf script, to decide if
that particular perf.data snapshot should be kept or not.
Implies --timestamp-filename, --no-buildid and --no-buildid-cache.
--dry-run
Parse options then exit. --dry-run can be used to detect errors in
cmdline options.
perf record --dry-run -e can act as a BPF script compiler if
llvm.dump-obj in config file is set to true.
--tail-synthesize
Instead of collecting non-sample events (for example, fork, comm,
mmap) at the beginning of record, collect them during finalizing an
output file. The collected non-sample events reflects the status of
the system when record is finished.
--overwrite
Makes all events use an overwritable ring buffer. An overwritable
ring buffer works like a flight recorder: when it gets full, the
kernel will overwrite the oldest records, that thus will never make
it to the perf.data file.
When --overwrite and --switch-output are used perf records and drops
events until it receives a signal, meaning that something unusual was
detected that warrants taking a snapshot of the most current events,
those fitting in the ring buffer at that moment.
overwrite attribute can also be set or canceled for an event using
config terms. For example: cycles/overwrite/ and
instructions/no-overwrite/.
Implies --tail-synthesize.
SEE ALSO
perf-stat(1), perf-list(1)
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