perf-record - Online in the Cloud

PROGRAM:

NAME

perf-record - Run a command and record its profile into perf.data

SYNOPSIS

perf record [-e <EVENT> | --event=EVENT] [-l] [-a] <command>
perf record [-e <EVENT> | --event=EVENT] [-l] [-a] — <command> [<options>]

DESCRIPTION

This command runs a command and gathers a performance counter profile from it, into
perf.data - without displaying anything.

This file can then be inspected later on, using perf report.

OPTIONS

<command>...
Any command you can specify in a shell.

-e, --event=
Select the PMU event. Selection can be:

· a symbolic event name (use perf list to list all events)

· a raw PMU event (eventsel+umask) in the form of rNNN where NNN is a hexadecimal
event descriptor.

· a symbolically formed PMU event like pmu/param1=0x3,param2/ where param1, param2,
etc are defined as formats for the PMU in
/sys/bus/event_sources/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_sources/devices/<pmu>/format/*
param1 and param2 are defined as formats for the PMU in:
/sys/bus/event_sources/devices/<pmu>/format/*

There are also some params which are not defined in .../<pmu>/format/*.
These params can be used to overload default config values per event.
Here is a list of the params.
- 'period': Set event sampling period
- 'freq': Set event sampling frequency
- 'time': Disable/enable time stamping. Acceptable values are 1 for
enabling time stamping. 0 for disabling time stamping.
The default is 1.
- 'call-graph': Disable/enable callgraph. Acceptable str are "fp" for
FP mode, "dwarf" for DWARF mode, "lbr" for LBR mode and
"no" for disable callgraph.
- 'stack-size': user stack size for dwarf mode
Note: If user explicitly sets options which conflict with the params,
the value set by the params will be overridden.

· a hardware breakpoint event in the form of \mem:addr[/len][:access] where addr is
the address in memory you want to break in. Access is the memory access type
(read, write, execute) it can be passed as follows: \mem:addr[:[r][w][x]]. len is
the range, number of bytes from specified addr, which the breakpoint will cover.
If you want to profile read-write accesses in 0x1000, just set mem:0x1000:rw. If
you want to profile write accesses in [0x1000~1008), just set mem:0x1000/8:w.

· a group of events surrounded by a pair of brace ("{event1,event2,...}"). Each
event is separated by commas and the group should be quoted to prevent the shell
interpretation. You also need to use --group on "perf report" to view group events
together.

--filter=<filter>
Event filter. This option should follow a event selector (-e) which selects tracepoint
event(s). Multiple --filter options are combined using &&.

--exclude-perf
Don’t record events issued by perf itself. This option should follow a event selector
(-e) which selects tracepoint event(s). It adds a filter expression common_pid !=
$PERFPID to filters. If other --filter exists, the new filter expression will be
combined with them by &&.

-a, --all-cpus
System-wide collection from all CPUs.

-p, --pid=
Record events on existing process ID (comma separated list).

-t, --tid=
Record events on existing thread ID (comma separated list). This option also disables
inheritance by default. Enable it by adding --inherit.

-u, --uid=
Record events in threads owned by uid. Name or number.

-r, --realtime=
Collect data with this RT SCHED_FIFO priority.

--no-buffering
Collect data without buffering.

-c, --count=
Event period to sample.

-o, --output=
Output file name.

-i, --no-inherit
Child tasks do not inherit counters.

-F, --freq=
Profile at this frequency.

-m, --mmap-pages=
Number of mmap data pages (must be a power of two) or size specification with appended
unit character - B/K/M/G. The size is rounded up to have nearest pages power of two
value. Also, by adding a comma, the number of mmap pages for AUX area tracing can be
specified.

--group
Put all events in a single event group. This precedes the --event option and remains
only for backward compatibility. See --event.

-g
Enables call-graph (stack chain/backtrace) recording.

--call-graph
Setup and enable call-graph (stack chain/backtrace) recording, implies -g. Default is
"fp".

Allows specifying "fp" (frame pointer) or "dwarf"
(DWARF's CFI - Call Frame Information) or "lbr"
(Hardware Last Branch Record facility) as the method to collect
the information used to show the call graphs.

In some systems, where binaries are build with gcc
--fomit-frame-pointer, using the "fp" method will produce bogus
call graphs, using "dwarf", if available (perf tools linked to
the libunwind or libdw library) should be used instead.
Using the "lbr" method doesn't require any compiler options. It
will produce call graphs from the hardware LBR registers. The
main limition is that it is only available on new Intel
platforms, such as Haswell. It can only get user call chain. It
doesn't work with branch stack sampling at the same time.

When "dwarf" recording is used, perf also records (user) stack dump
when sampled. Default size of the stack dump is 8192 (bytes).
User can change the size by passing the size after comma like
"--call-graph dwarf,4096".

-q, --quiet
Don’t print any message, useful for scripting.

-v, --verbose
Be more verbose (show counter open errors, etc).

-s, --stat
Record per-thread event counts. Use it with perf report -T to see the values.

-d, --data
Record the sample addresses.

-T, --timestamp
Record the sample timestamps. Use it with perf report -D to see the timestamps, for
instance.

-P, --period
Record the sample period.

-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.

-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.

-G name,..., --cgroup name,...
monitor only in the container (cgroup) called "name". This option is available only in
per-cpu mode. The cgroup filesystem must be mounted. All threads belonging to
container "name" are monitored when they run on the monitored CPUs. Multiple cgroups
can be provided. Each cgroup is applied to the corresponding event, i.e., first cgroup
to first event, second cgroup to second event and so on. It is possible to provide an
empty cgroup (monitor all the time) using, e.g., -G foo,,bar. Cgroups must have
corresponding events, i.e., they always refer to events defined earlier on the command
line.

-b, --branch-any
Enable taken branch stack sampling. Any type of taken branch may be sampled. This is a
shortcut for --branch-filter any. See --branch-filter for more infos.

-j, --branch-filter
Enable taken branch stack sampling. Each sample captures a series of consecutive taken
branches. The number of branches captured with each sample depends on the underlying
hardware, the type of branches of interest, and the executed code. It is possible to
select the types of branches captured by enabling filters. The following filters are
defined:

· any: any type of branches

· any_call: any function call or system call

· any_ret: any function return or system call return

· ind_call: any indirect branch

· call: direct calls, including far (to/from kernel) calls

· u: only when the branch target is at the user level

· k: only when the branch target is in the kernel

· hv: only when the target is at the hypervisor level

· in_tx: only when the target is in a hardware transaction

· no_tx: only when the target is not in a hardware transaction

· abort_tx: only when the target is a hardware transaction abort

· cond: conditional branches

The option requires at least one branch type among any, any_call, any_ret, ind_call,
cond. The privilege levels may be omitted, in which case, the privilege levels of the
associated event are applied to the branch filter. Both kernel (k) and hypervisor (hv)
privilege levels are subject to permissions. When sampling on multiple events, branch
stack sampling is enabled for all the sampling events. The sampled branch type is the
same for all events. The various filters must be specified as a comma separated list:
--branch-filter any_ret,u,k Note that this feature may not be available on all
processors.

--weight
Enable weightened sampling. An additional weight is recorded per sample and can be
displayed with the weight and local_weight sort keys. This currently works for TSX
abort events and some memory events in precise mode on modern Intel CPUs.

--transaction
Record transaction flags for transaction related events.

--per-thread
Use per-thread mmaps. By default per-cpu mmaps are created. This option overrides that
and uses per-thread mmaps. A side-effect of that is that inheritance is automatically
disabled. --per-thread is ignored with a warning if combined with -a or -C options.

-D, --delay=
After starting the program, wait msecs before measuring. This is useful to filter out
the startup phase of the program, which is often very different.

-I, --intr-regs
Capture machine state (registers) at interrupt, i.e., on counter overflows for each
sample. List of captured registers depends on the architecture. This option is off by
default. It is possible to select the registers to sample using their symbolic names,
e.g. on x86, ax, si. To list the available registers use --intr-regs=\?. To name
registers, pass a comma separated list such as --intr-regs=ax,bx. The list of register
is architecture dependent.

--running-time
Record running and enabled time for read events (:S)

-k, --clockid
Sets the clock id to use for the various time fields in the perf_event_type records.
See clock_gettime(). In particular CLOCK_MONOTONIC and CLOCK_MONOTONIC_RAW are
supported, some events might also allow CLOCK_BOOTTIME, CLOCK_REALTIME and CLOCK_TAI.

-S, --snapshot
Select AUX area tracing Snapshot Mode. This option is valid only with an AUX area
tracing event. Optionally the number of bytes to capture per snapshot can be
specified. In Snapshot Mode, trace data is captured only when signal SIGUSR2 is
received.

--proc-map-timeout
When processing pre-existing threads /proc/XXX/mmap, it may take a long time, because
the file may be huge. A time out is needed in such cases. This option sets the time
out limit. The default value is 500 ms.

--switch-events
Record context switch events i.e. events of type PERF_RECORD_SWITCH or
PERF_RECORD_SWITCH_CPU_WIDE.

--clang-path
Path to clang binary to use for compiling BPF scriptlets.

--clang-opt
Options passed to clang when compiling BPF scriptlets.

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