<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 symbolic or raw PMU event followed by an optional colon
and a list of event modifiers, e.g., cpu-cycles:p. See
the perf-list(1) man page for details on event modifiers.
• 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 parameters which are not defined in .../<pmu>/format/*.
These params can be used to overload default config values per event.
Here are some common parameters:
- '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
- 'name' : User defined event name. Single quotes (') may be used to
escape symbols in the name from parsing by shell and tool
like this: name=\'CPU_CLK_UNHALTED.THREAD:cmask=0x1\'.
- 'aux-output': Generate AUX records instead of events. This requires
that an AUX area event is also provided.
- 'aux-sample-size': Set sample size for AUX area sampling. If the
'--aux-sample' option has been used, set aux-sample-size=0 to disable
AUX area sampling for the event.
See the linkperf:perf-list[1] man page for more parameters.
Note: If user explicitly sets options which conflict with the params,
the value set by the parameters 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 BPF source file (ending in .c) or a precompiled object
file (ending in .o) selects one or more BPF events. The
BPF program can attach to various perf events based on
the ELF section names.
When processing a '.c' file, perf searches an installed LLVM to compile it
into an object file first. Optional clang options can be passed via the
'--clang-opt' command line option, e.g.:
perf record --clang-opt "-DLINUX_VERSION_CODE=0x50000" \
-e tests/bpf-script-example.c
Note: '--clang-opt' must be placed before '--event/-e'.
• 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 an 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 an 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 (default if no target is
specified).
-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. Use max to use the currently
maximum allowed frequency, i.e. the value in the
kernel.perf_event_max_sample_rate sysctl. Will throttle down
to the currently maximum allowed frequency. See
--strict-freq.
--strict-freq
Fail if the specified frequency can't be used.
-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 for both
kernel space and user space.
--call-graph
Setup and enable call-graph (stack chain/backtrace)
recording, implies -g. Default is "fp" (for user space).
The unwinding method used for kernel space is dependent on the
unwinder used by the active kernel configuration, i.e
CONFIG_UNWINDER_FRAME_POINTER (fp) or CONFIG_UNWINDER_ORC (orc)
Any option specified here controls the method used for user space.
Valid options are "fp" (frame pointer), "dwarf" (DWARF's CFI -
Call Frame Information) or "lbr" (Hardware Last Branch Record
facility).
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 limitation 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 virtual addresses.
--phys-data
Record the sample physical addresses.
--data-page-size
Record the sampled data address data page size.
--code-page-size
Record the sampled code address (ip) page size
-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. If the user wants to track multiple events
for a specific cgroup, the user can use -e e1 -e e2 -G
foo,foo or just use -e e1 -e e2 -G foo.
If wanting to monitor, say, cycles for a cgroup and also for
system wide, this command line can be used: perf stat -e cycles
-G cgroup_name -a -e cycles.
-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
• save_type: save branch type during sampling in case
binary is not available later
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.
--namespaces
Record events of type PERF_RECORD_NAMESPACES. This enables
cgroup_id sort key.
--all-cgroups
Record events of type PERF_RECORD_CGROUP. This enables cgroup
sort key.
--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 (-1:
start with events disabled). 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.
--user-regs
Similar to -I, but capture user registers at sample time. To
list the available user registers use --user-regs=\?.
--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, certain
snapshot capturing parameters can be specified in a string
that follows this option: e: take one last snapshot on exit;
guarantees that there is at least one snapshot in the output
file; <size>: if the PMU supports this, specify the desired
snapshot size.
In Snapshot Mode trace data is captured only when signal SIGUSR2
is received and on exit if the above e option is given.
--aux-sample[=OPTIONS]
Select AUX area sampling. At least one of the events selected
by the -e option must be an AUX area event. Samples on other
events will be created containing data from the AUX area.
Optionally sample size may be specified, otherwise it
defaults to 4KiB.
--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. In some
cases (e.g. Intel PT or CoreSight) switch events will be
enabled automatically, which can be suppressed by by the
option --no-switch-events.
--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.
--buildid-mmap
Record build ids in mmap2 events, disables build id cache
(implies --no-buildid).
--aio[=n]
Use <n> control blocks in asynchronous (Posix AIO) trace
writing mode (default: 1, max: 4). Asynchronous mode is
supported only when linking Perf tool with libc library
providing implementation for Posix AIO API.
--affinity=mode
Set affinity mask of trace reading thread according to the
policy defined by mode value: node - thread affinity mask is
set to NUMA node cpu mask of the processed mmap buffer cpu -
thread affinity mask is set to cpu of the processed mmap
buffer
--mmap-flush=number
Specify minimal number of bytes that is extracted from mmap
data pages and processed for output. One can specify the
number using B/K/M/G suffixes.
The maximal allowed value is a quarter of the size of mmaped data
pages.
The default option value is 1 byte which means that every time
that the output writing thread finds some new data in the mmaped
buffer the data is extracted, possibly compressed (-z) and
written to the output, perf.data or pipe.
Larger data chunks are compressed more effectively in comparison
to smaller chunks so extraction of larger chunks from the mmap
data pages is preferable from the perspective of output size
reduction.
Also at some cases executing less output write syscalls with
bigger data size can take less time than executing more output
write syscalls with smaller data size thus lowering runtime
profiling overhead.
-z, --compression-level[=n]
Produce compressed trace using specified level n (default: 1
- fastest compression, 22 - smallest trace)
--all-kernel
Configure all used events to run in kernel space.
--all-user
Configure all used events to run in user space.
--kernel-callchains
Collect callchains only from kernel space. I.e. this option
sets perf_event_attr.exclude_callchain_user to 1.
--user-callchains
Collect callchains only from user space. I.e. this option
sets perf_event_attr.exclude_callchain_kernel to 1.
Don't use both --kernel-callchains and --user-callchains at the
same time or no callchains will be collected.
--timestamp-filename Append timestamp to output file name.
--timestamp-boundary
Record timestamp boundary (time of first/last samples).
--switch-output[=mode]
Generate multiple perf.data files, timestamp prefixed,
switching to a new one based on mode value: "signal" - when
receiving a SIGUSR2 (default value) or <size> - when reaching
the size threshold, size is expected to be a number with
appended unit character - B/K/M/G <time> - when reaching the
time threshold, size is expected to be a number with appended
unit character - s/m/h/d
Note: the precision of the size threshold hugely depends
on your configuration - the number and size of your ring
buffers (-m). It is generally more precise for higher sizes
(like >5M), for lower values expect different sizes.
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. The reason for the latter two is to reduce
the data file switching overhead. You can still switch them on
with:
--switch-output --no-no-buildid --no-no-buildid-cache
--switch-output-event
Events that will cause the switch of the perf.data file,
auto-selecting --switch-output=signal, the results are
similar as internally the side band thread will also send a
SIGUSR2 to the main one.
Uses the same syntax as --event, it will just not be recorded,
serving only to switch the perf.data file as soon as the
--switch-output event is processed by a separate sideband thread.
This sideband thread is also used to other purposes, like
processing the PERF_RECORD_BPF_EVENT records as they happen,
asking the kernel for extra BPF information, etc.
--switch-max-files=N
When rotating perf.data with --switch-output, only keep N
files.
--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.
--kcore
Make a copy of /proc/kcore and place it into a directory with
the perf data file.
--max-size=<size>
Limit the sample data max size, <size> is expected to be a
number with appended unit character - B/K/M/G
--num-thread-synthesize
The number of threads to run when synthesizing events for
existing processes. By default, the number of threads equals
1.
--control=fifo:ctl-fifo[,ack-fifo], --control=fd:ctl-fd[,ack-fd]
ctl-fifo / ack-fifo are opened and used as ctl-fd / ack-fd as
follows. Listen on ctl-fd descriptor for command to control
measurement.
Available commands: enable : enable events disable : disable
events enable name : enable event name disable name : disable
event name snapshot : AUX area tracing snapshot). stop : stop
perf record ping : ping
'evlist [-v|-g|-F] : display all events
-F Show just the sample frequency used for each event.
-v Show all fields.
-g Show event group information.
Measurements can be started with events disabled using --delay=-1
option. Optionally send control command completion (ack\n) to
ack-fd descriptor to synchronize with the controlling process.
Example of bash shell script to enable and disable events during
measurements:
#!/bin/bash
ctl_dir=/tmp/
ctl_fifo=${ctl_dir}perf_ctl.fifo
test -p ${ctl_fifo} && unlink ${ctl_fifo}
mkfifo ${ctl_fifo}
exec {ctl_fd}<>${ctl_fifo}
ctl_ack_fifo=${ctl_dir}perf_ctl_ack.fifo
test -p ${ctl_ack_fifo} && unlink ${ctl_ack_fifo}
mkfifo ${ctl_ack_fifo}
exec {ctl_fd_ack}<>${ctl_ack_fifo}
perf record -D -1 -e cpu-cycles -a \
--control fd:${ctl_fd},${ctl_fd_ack} \
-- sleep 30 &
perf_pid=$!
sleep 5 && echo 'enable' >&${ctl_fd} && read -u ${ctl_fd_ack} e1 && echo "enabled(${e1})"
sleep 10 && echo 'disable' >&${ctl_fd} && read -u ${ctl_fd_ack} d1 && echo "disabled(${d1})"
exec {ctl_fd_ack}>&-
unlink ${ctl_ack_fifo}
exec {ctl_fd}>&-
unlink ${ctl_fifo}
wait -n ${perf_pid}
exit $?
