perf-record(1)
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==============
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NAME
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----
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perf-record - Run a command and record its profile into perf.data
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SYNOPSIS
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--------
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[verse]
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'perf record' [-e <EVENT> | --event=EVENT] [-a] <command>
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'perf record' [-e <EVENT> | --event=EVENT] [-a] -- <command> [<options>]
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DESCRIPTION
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-----------
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This command runs a command and gathers a performance counter profile
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from it, into perf.data - without displaying anything.
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This file can then be inspected later on, using 'perf report'.
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OPTIONS
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-------
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<command>...::
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Any command you can specify in a shell.
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-e::
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--event=::
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Select the PMU event. Selection can be:
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- a symbolic event name (use 'perf list' to list all events)
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- a raw PMU event (eventsel+umask) in the form of rNNN where NNN is a
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hexadecimal event descriptor.
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- a symbolic or raw PMU event followed by an optional colon
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and a list of event modifiers, e.g., cpu-cycles:p. See the
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linkperf:perf-list[1] man page for details on event modifiers.
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- a symbolically formed PMU event like 'pmu/param1=0x3,param2/' where
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'param1', 'param2', etc are defined as formats for the PMU in
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/sys/bus/event_source/devices/<pmu>/format/*.
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- a symbolically formed event like 'pmu/config=M,config1=N,config3=K/'
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where M, N, K are numbers (in decimal, hex, octal format). Acceptable
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values for each of 'config', 'config1' and 'config2' are defined by
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corresponding entries in /sys/bus/event_source/devices/<pmu>/format/*
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param1 and param2 are defined as formats for the PMU in:
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/sys/bus/event_source/devices/<pmu>/format/*
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There are also some parameters which are not defined in .../<pmu>/format/*.
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These params can be used to overload default config values per event.
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Here are some common parameters:
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- 'period': Set event sampling period
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- 'freq': Set event sampling frequency
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- 'time': Disable/enable time stamping. Acceptable values are 1 for
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enabling time stamping. 0 for disabling time stamping.
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The default is 1.
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- 'call-graph': Disable/enable callgraph. Acceptable str are "fp" for
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FP mode, "dwarf" for DWARF mode, "lbr" for LBR mode and
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"no" for disable callgraph.
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- 'stack-size': user stack size for dwarf mode
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- 'name' : User defined event name. Single quotes (') may be used to
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escape symbols in the name from parsing by shell and tool
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like this: name=\'CPU_CLK_UNHALTED.THREAD:cmask=0x1\'.
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- 'aux-output': Generate AUX records instead of events. This requires
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that an AUX area event is also provided.
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- 'aux-sample-size': Set sample size for AUX area sampling. If the
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'--aux-sample' option has been used, set aux-sample-size=0 to disable
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AUX area sampling for the event.
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See the linkperf:perf-list[1] man page for more parameters.
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Note: If user explicitly sets options which conflict with the params,
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the value set by the parameters will be overridden.
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Also not defined in .../<pmu>/format/* are PMU driver specific
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configuration parameters. Any configuration parameter preceded by
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the letter '@' is not interpreted in user space and sent down directly
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to the PMU driver. For example:
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perf record -e some_event/@cfg1,@cfg2=config/ ...
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will see 'cfg1' and 'cfg2=config' pushed to the PMU driver associated
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with the event for further processing. There is no restriction on
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what the configuration parameters are, as long as their semantic is
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understood and supported by the PMU driver.
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- a hardware breakpoint event in the form of '\mem:addr[/len][:access]'
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where addr is the address in memory you want to break in.
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Access is the memory access type (read, write, execute) it can
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be passed as follows: '\mem:addr[:[r][w][x]]'. len is the range,
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number of bytes from specified addr, which the breakpoint will cover.
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If you want to profile read-write accesses in 0x1000, just set
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'mem:0x1000:rw'.
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If you want to profile write accesses in [0x1000~1008), just set
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'mem:0x1000/8:w'.
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- a BPF source file (ending in .c) or a precompiled object file (ending
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in .o) selects one or more BPF events.
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The BPF program can attach to various perf events based on the ELF section
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names.
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When processing a '.c' file, perf searches an installed LLVM to compile it
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into an object file first. Optional clang options can be passed via the
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'--clang-opt' command line option, e.g.:
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perf record --clang-opt "-DLINUX_VERSION_CODE=0x50000" \
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-e tests/bpf-script-example.c
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Note: '--clang-opt' must be placed before '--event/-e'.
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- a group of events surrounded by a pair of brace ("{event1,event2,...}").
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Each event is separated by commas and the group should be quoted to
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prevent the shell interpretation. You also need to use --group on
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"perf report" to view group events together.
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--filter=<filter>::
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Event filter. This option should follow an event selector (-e) which
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selects either tracepoint event(s) or a hardware trace PMU
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(e.g. Intel PT or CoreSight).
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- tracepoint filters
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In the case of tracepoints, multiple '--filter' options are combined
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using '&&'.
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- address filters
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A hardware trace PMU advertises its ability to accept a number of
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address filters by specifying a non-zero value in
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/sys/bus/event_source/devices/<pmu>/nr_addr_filters.
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Address filters have the format:
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filter|start|stop|tracestop <start> [/ <size>] [@<file name>]
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Where:
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- 'filter': defines a region that will be traced.
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- 'start': defines an address at which tracing will begin.
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- 'stop': defines an address at which tracing will stop.
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- 'tracestop': defines a region in which tracing will stop.
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<file name> is the name of the object file, <start> is the offset to the
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code to trace in that file, and <size> is the size of the region to
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trace. 'start' and 'stop' filters need not specify a <size>.
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If no object file is specified then the kernel is assumed, in which case
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the start address must be a current kernel memory address.
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<start> can also be specified by providing the name of a symbol. If the
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symbol name is not unique, it can be disambiguated by inserting #n where
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'n' selects the n'th symbol in address order. Alternately #0, #g or #G
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select only a global symbol. <size> can also be specified by providing
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the name of a symbol, in which case the size is calculated to the end
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of that symbol. For 'filter' and 'tracestop' filters, if <size> is
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omitted and <start> is a symbol, then the size is calculated to the end
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of that symbol.
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If <size> is omitted and <start> is '*', then the start and size will
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be calculated from the first and last symbols, i.e. to trace the whole
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file.
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If symbol names (or '*') are provided, they must be surrounded by white
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space.
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The filter passed to the kernel is not necessarily the same as entered.
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To see the filter that is passed, use the -v option.
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The kernel may not be able to configure a trace region if it is not
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within a single mapping. MMAP events (or /proc/<pid>/maps) can be
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examined to determine if that is a possibility.
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Multiple filters can be separated with space or comma.
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--exclude-perf::
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Don't record events issued by perf itself. This option should follow
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an event selector (-e) which selects tracepoint event(s). It adds a
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filter expression 'common_pid != $PERFPID' to filters. If other
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'--filter' exists, the new filter expression will be combined with
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them by '&&'.
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-a::
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--all-cpus::
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System-wide collection from all CPUs (default if no target is specified).
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-p::
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--pid=::
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Record events on existing process ID (comma separated list).
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-t::
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--tid=::
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Record events on existing thread ID (comma separated list).
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This option also disables inheritance by default. Enable it by adding
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--inherit.
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-u::
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--uid=::
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Record events in threads owned by uid. Name or number.
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-r::
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--realtime=::
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Collect data with this RT SCHED_FIFO priority.
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--no-buffering::
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Collect data without buffering.
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-c::
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--count=::
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Event period to sample.
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-o::
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--output=::
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Output file name.
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-i::
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--no-inherit::
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Child tasks do not inherit counters.
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-F::
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--freq=::
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Profile at this frequency. Use 'max' to use the currently maximum
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allowed frequency, i.e. the value in the kernel.perf_event_max_sample_rate
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sysctl. Will throttle down to the currently maximum allowed frequency.
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See --strict-freq.
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--strict-freq::
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Fail if the specified frequency can't be used.
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-m::
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--mmap-pages=::
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Number of mmap data pages (must be a power of two) or size
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specification with appended unit character - B/K/M/G. The
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size is rounded up to have nearest pages power of two value.
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Also, by adding a comma, the number of mmap pages for AUX
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area tracing can be specified.
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--group::
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Put all events in a single event group. This precedes the --event
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option and remains only for backward compatibility. See --event.
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-g::
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Enables call-graph (stack chain/backtrace) recording for both
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kernel space and user space.
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--call-graph::
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Setup and enable call-graph (stack chain/backtrace) recording,
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implies -g. Default is "fp" (for user space).
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The unwinding method used for kernel space is dependent on the
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unwinder used by the active kernel configuration, i.e
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CONFIG_UNWINDER_FRAME_POINTER (fp) or CONFIG_UNWINDER_ORC (orc)
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Any option specified here controls the method used for user space.
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Valid options are "fp" (frame pointer), "dwarf" (DWARF's CFI -
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Call Frame Information) or "lbr" (Hardware Last Branch Record
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facility).
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In some systems, where binaries are build with gcc
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--fomit-frame-pointer, using the "fp" method will produce bogus
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call graphs, using "dwarf", if available (perf tools linked to
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the libunwind or libdw library) should be used instead.
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Using the "lbr" method doesn't require any compiler options. It
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will produce call graphs from the hardware LBR registers. The
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main limitation is that it is only available on new Intel
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platforms, such as Haswell. It can only get user call chain. It
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doesn't work with branch stack sampling at the same time.
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When "dwarf" recording is used, perf also records (user) stack dump
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when sampled. Default size of the stack dump is 8192 (bytes).
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User can change the size by passing the size after comma like
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"--call-graph dwarf,4096".
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-q::
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--quiet::
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Don't print any message, useful for scripting.
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-v::
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--verbose::
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Be more verbose (show counter open errors, etc).
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-s::
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--stat::
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Record per-thread event counts. Use it with 'perf report -T' to see
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the values.
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-d::
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--data::
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Record the sample virtual addresses.
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--phys-data::
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Record the sample physical addresses.
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-T::
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--timestamp::
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Record the sample timestamps. Use it with 'perf report -D' to see the
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timestamps, for instance.
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-P::
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--period::
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Record the sample period.
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--sample-cpu::
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Record the sample cpu.
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-n::
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--no-samples::
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Don't sample.
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-R::
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--raw-samples::
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Collect raw sample records from all opened counters (default for tracepoint counters).
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-C::
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--cpu::
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Collect samples only on the list of CPUs provided. Multiple CPUs can be provided as a
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comma-separated list with no space: 0,1. Ranges of CPUs are specified with -: 0-2.
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In per-thread mode with inheritance mode on (default), samples are captured only when
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the thread executes on the designated CPUs. Default is to monitor all CPUs.
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-B::
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--no-buildid::
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Do not save the build ids of binaries in the perf.data files. This skips
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post processing after recording, which sometimes makes the final step in
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the recording process to take a long time, as it needs to process all
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events looking for mmap records. The downside is that it can misresolve
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symbols if the workload binaries used when recording get locally rebuilt
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or upgraded, because the only key available in this case is the
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pathname. You can also set the "record.build-id" config variable to
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'skip to have this behaviour permanently.
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-N::
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--no-buildid-cache::
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Do not update the buildid cache. This saves some overhead in situations
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where the information in the perf.data file (which includes buildids)
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is sufficient. You can also set the "record.build-id" config variable to
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'no-cache' to have the same effect.
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-G name,...::
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--cgroup name,...::
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monitor only in the container (cgroup) called "name". This option is available only
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in per-cpu mode. The cgroup filesystem must be mounted. All threads belonging to
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container "name" are monitored when they run on the monitored CPUs. Multiple cgroups
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can be provided. Each cgroup is applied to the corresponding event, i.e., first cgroup
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to first event, second cgroup to second event and so on. It is possible to provide
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an empty cgroup (monitor all the time) using, e.g., -G foo,,bar. Cgroups must have
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corresponding events, i.e., they always refer to events defined earlier on the command
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line. If the user wants to track multiple events for a specific cgroup, the user can
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use '-e e1 -e e2 -G foo,foo' or just use '-e e1 -e e2 -G foo'.
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If wanting to monitor, say, 'cycles' for a cgroup and also for system wide, this
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command line can be used: 'perf stat -e cycles -G cgroup_name -a -e cycles'.
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-b::
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--branch-any::
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Enable taken branch stack sampling. Any type of taken branch may be sampled.
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This is a shortcut for --branch-filter any. See --branch-filter for more infos.
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-j::
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--branch-filter::
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Enable taken branch stack sampling. Each sample captures a series of consecutive
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taken branches. The number of branches captured with each sample depends on the
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underlying hardware, the type of branches of interest, and the executed code.
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It is possible to select the types of branches captured by enabling filters. The
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following filters are defined:
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- any: any type of branches
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- any_call: any function call or system call
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- any_ret: any function return or system call return
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- ind_call: any indirect branch
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- call: direct calls, including far (to/from kernel) calls
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- u: only when the branch target is at the user level
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- k: only when the branch target is in the kernel
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- hv: only when the target is at the hypervisor level
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- in_tx: only when the target is in a hardware transaction
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- no_tx: only when the target is not in a hardware transaction
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- abort_tx: only when the target is a hardware transaction abort
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- cond: conditional branches
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- save_type: save branch type during sampling in case binary is not available later
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+
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The option requires at least one branch type among any, any_call, any_ret, ind_call, cond.
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The privilege levels may be omitted, in which case, the privilege levels of the associated
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event are applied to the branch filter. Both kernel (k) and hypervisor (hv) privilege
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levels are subject to permissions. When sampling on multiple events, branch stack sampling
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is enabled for all the sampling events. The sampled branch type is the same for all events.
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The various filters must be specified as a comma separated list: --branch-filter any_ret,u,k
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Note that this feature may not be available on all processors.
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--weight::
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Enable weightened sampling. An additional weight is recorded per sample and can be
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displayed with the weight and local_weight sort keys. This currently works for TSX
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abort events and some memory events in precise mode on modern Intel CPUs.
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--namespaces::
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Record events of type PERF_RECORD_NAMESPACES. This enables 'cgroup_id' sort key.
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--all-cgroups::
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Record events of type PERF_RECORD_CGROUP. This enables 'cgroup' sort key.
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--transaction::
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Record transaction flags for transaction related events.
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--per-thread::
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Use per-thread mmaps. By default per-cpu mmaps are created. This option
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overrides that and uses per-thread mmaps. A side-effect of that is that
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inheritance is automatically disabled. --per-thread is ignored with a warning
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if combined with -a or -C options.
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-D::
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--delay=::
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After starting the program, wait msecs before measuring (-1: start with events
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disabled). This is useful to filter out the startup phase of the program, which
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is often very different.
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-I::
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--intr-regs::
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Capture machine state (registers) at interrupt, i.e., on counter overflows for
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each sample. List of captured registers depends on the architecture. This option
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is off by default. It is possible to select the registers to sample using their
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symbolic names, e.g. on x86, ax, si. To list the available registers use
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--intr-regs=\?. To name registers, pass a comma separated list such as
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--intr-regs=ax,bx. The list of register is architecture dependent.
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--user-regs::
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Similar to -I, but capture user registers at sample time. To list the available
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user registers use --user-regs=\?.
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--running-time::
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Record running and enabled time for read events (:S)
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-k::
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--clockid::
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Sets the clock id to use for the various time fields in the perf_event_type
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records. See clock_gettime(). In particular CLOCK_MONOTONIC and
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CLOCK_MONOTONIC_RAW are supported, some events might also allow
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CLOCK_BOOTTIME, CLOCK_REALTIME and CLOCK_TAI.
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-S::
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--snapshot::
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Select AUX area tracing Snapshot Mode. This option is valid only with an
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AUX area tracing event. Optionally, certain snapshot capturing parameters
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can be specified in a string that follows this option:
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'e': take one last snapshot on exit; guarantees that there is at least one
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snapshot in the output file;
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<size>: if the PMU supports this, specify the desired snapshot size.
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In Snapshot Mode trace data is captured only when signal SIGUSR2 is received
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and on exit if the above 'e' option is given.
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--aux-sample[=OPTIONS]::
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Select AUX area sampling. At least one of the events selected by the -e option
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must be an AUX area event. Samples on other events will be created containing
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data from the AUX area. Optionally sample size may be specified, otherwise it
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defaults to 4KiB.
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--proc-map-timeout::
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When processing pre-existing threads /proc/XXX/mmap, it may take a long time,
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because the file may be huge. A time out is needed in such cases.
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This option sets the time out limit. The default value is 500 ms.
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--switch-events::
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Record context switch events i.e. events of type PERF_RECORD_SWITCH or
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PERF_RECORD_SWITCH_CPU_WIDE. In some cases (e.g. Intel PT or CoreSight)
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switch events will be enabled automatically, which can be suppressed by
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by the option --no-switch-events.
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--clang-path=PATH::
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Path to clang binary to use for compiling BPF scriptlets.
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(enabled when BPF support is on)
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--clang-opt=OPTIONS::
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Options passed to clang when compiling BPF scriptlets.
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(enabled when BPF support is on)
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--vmlinux=PATH::
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Specify vmlinux path which has debuginfo.
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(enabled when BPF prologue is on)
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--buildid-all::
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Record build-id of all DSOs regardless whether it's actually hit or not.
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--aio[=n]::
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Use <n> control blocks in asynchronous (Posix AIO) trace writing mode (default: 1, max: 4).
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Asynchronous mode is supported only when linking Perf tool with libc library
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providing implementation for Posix AIO API.
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--affinity=mode::
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Set affinity mask of trace reading thread according to the policy defined by 'mode' value:
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node - thread affinity mask is set to NUMA node cpu mask of the processed mmap buffer
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cpu - thread affinity mask is set to cpu of the processed mmap buffer
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--mmap-flush=number::
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Specify minimal number of bytes that is extracted from mmap data pages and
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processed for output. One can specify the number using B/K/M/G suffixes.
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The maximal allowed value is a quarter of the size of mmaped data pages.
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The default option value is 1 byte which means that every time that the output
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writing thread finds some new data in the mmaped buffer the data is extracted,
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possibly compressed (-z) and written to the output, perf.data or pipe.
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Larger data chunks are compressed more effectively in comparison to smaller
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chunks so extraction of larger chunks from the mmap data pages is preferable
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from the perspective of output size reduction.
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Also at some cases executing less output write syscalls with bigger data size
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can take less time than executing more output write syscalls with smaller data
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size thus lowering runtime profiling overhead.
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-z::
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--compression-level[=n]::
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Produce compressed trace using specified level n (default: 1 - fastest compression,
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22 - smallest trace)
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--all-kernel::
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Configure all used events to run in kernel space.
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--all-user::
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Configure all used events to run in user space.
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--kernel-callchains::
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Collect callchains only from kernel space. I.e. this option sets
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perf_event_attr.exclude_callchain_user to 1.
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--user-callchains::
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Collect callchains only from user space. I.e. this option sets
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perf_event_attr.exclude_callchain_kernel to 1.
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Don't use both --kernel-callchains and --user-callchains at the same time or no
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callchains will be collected.
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--timestamp-filename
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Append timestamp to output file name.
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--timestamp-boundary::
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Record timestamp boundary (time of first/last samples).
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--switch-output[=mode]::
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Generate multiple perf.data files, timestamp prefixed, switching to a new one
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based on 'mode' value:
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"signal" - when receiving a SIGUSR2 (default value) or
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<size> - when reaching the size threshold, size is expected to
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be a number with appended unit character - B/K/M/G
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<time> - when reaching the time threshold, size is expected to
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be a number with appended unit character - s/m/h/d
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Note: the precision of the size threshold hugely depends
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on your configuration - the number and size of your ring
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buffers (-m). It is generally more precise for higher sizes
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(like >5M), for lower values expect different sizes.
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A possible use case is to, given an external event, slice the perf.data file
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that gets then processed, possibly via a perf script, to decide if that
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particular perf.data snapshot should be kept or not.
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Implies --timestamp-filename, --no-buildid and --no-buildid-cache.
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The reason for the latter two is to reduce the data file switching
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overhead. You can still switch them on with:
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--switch-output --no-no-buildid --no-no-buildid-cache
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--switch-output-event::
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Events that will cause the switch of the perf.data file, auto-selecting
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--switch-output=signal, the results are similar as internally the side band
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thread will also send a SIGUSR2 to the main one.
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Uses the same syntax as --event, it will just not be recorded, serving only to
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switch the perf.data file as soon as the --switch-output event is processed by
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a separate sideband thread.
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This sideband thread is also used to other purposes, like processing the
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PERF_RECORD_BPF_EVENT records as they happen, asking the kernel for extra BPF
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information, etc.
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--switch-max-files=N::
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When rotating perf.data with --switch-output, only keep N files.
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--dry-run::
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Parse options then exit. --dry-run can be used to detect errors in cmdline
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options.
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'perf record --dry-run -e' can act as a BPF script compiler if llvm.dump-obj
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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]
|
