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- perf-record(1)
- ==============
- NAME
- ----
- perf-record - Run a command and record its profile into perf.data
- SYNOPSIS
- --------
- [verse]
- 'perf record' [-e <EVENT> | --event=EVENT] [-a] <command>
- 'perf record' [-e <EVENT> | --event=EVENT] [-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 symbolic or raw PMU event followed by an optional colon
- and a list of event modifiers, e.g., cpu-cycles:p. See the
- linkperf: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.
- -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.
- --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.
- ifdef::HAVE_LIBPFM[]
- --pfm-events events::
- Select a PMU event using libpfm4 syntax (see http://perfmon2.sf.net)
- including support for event filters. For example '--pfm-events
- inst_retired:any_p:u:c=1:i'. More than one event can be passed to the
- option using the comma separator. Hardware events and generic hardware
- events cannot be mixed together. The latter must be used with the -e
- option. The -e option and this one can be mixed and matched. Events
- can be grouped using the {} notation.
- endif::HAVE_LIBPFM[]
- --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 ('enable': enable events,
- 'disable': disable events, 'snapshot': AUX area tracing snapshot). 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 $?
- SEE ALSO
- --------
- linkperf:perf-stat[1], linkperf:perf-list[1], linkperf:perf-intel-pt[1]
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