PERF-RECORD(1) perf Manual PERF-RECORD(1)
NAME
perf-record - Run a command and record its profile into perf.data
SYNOPSIS
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 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 $?
INTEL HYBRID SUPPORT
Support for Intel hybrid events within perf tools.
For some Intel platforms, such as AlderLake, which is hybrid platform
and it consists of atom cpu and core cpu. Each cpu has dedicated event
list. Part of events are available on core cpu, part of events are
available on atom cpu and even part of events are available on both.
Kernel exports two new cpu pmus via sysfs: /sys/devices/cpu_core
/sys/devices/cpu_atom
The cpus files are created under the directories. For example,
cat /sys/devices/cpu_core/cpus 0-15
cat /sys/devices/cpu_atom/cpus 16-23
It indicates cpu0-cpu15 are core cpus and cpu16-cpu23 are atom cpus.
Quickstart
LIST HYBRID EVENT
As before, use perf-list to list the symbolic event.
perf list
inst_retired.any [Fixed Counter: Counts the number of instructions
retired. Unit: cpu_atom] inst_retired.any [Number of instructions
retired. Fixed Counter - architectural event. Unit: cpu_core]
The Unit: xxx is added to brief description to indicate which pmu the
event is belong to. Same event name but with different pmu can be
supported.
ENABLE HYBRID EVENT WITH A SPECIFIC PMU
To enable a core only event or atom only event, following syntax is
supported:
cpu_core/<event name>/
or
cpu_atom/<event name>/
For example, count the cycles event on core cpus.
perf stat -e cpu_core/cycles/
CREATE TWO EVENTS FOR ONE HARDWARE EVENT AUTOMATICALLY
When creating one event and the event is available on both atom and
core, two events are created automatically. One is for atom, the other
is for core. Most of hardware events and cache events are available on
both cpu_core and cpu_atom.
For hardware events, they have pre-defined configs (e.g. 0 for cycles).
But on hybrid platform, kernel needs to know where the event comes from
(from atom or from core). The original perf event type
PERF_TYPE_HARDWARE can’t carry pmu information. So now this type is
extended to be PMU aware type. The PMU type ID is stored at
attr.config[63:32].
PMU type ID is retrieved from sysfs. /sys/devices/cpu_atom/type
/sys/devices/cpu_core/type
The new attr.config layout for PERF_TYPE_HARDWARE:
PERF_TYPE_HARDWARE: 0xEEEEEEEE000000AA AA: hardware event ID EEEEEEEE:
PMU type ID
Cache event is similar. The type PERF_TYPE_HW_CACHE is extended to be
PMU aware type. The PMU type ID is stored at attr.config[63:32].
The new attr.config layout for PERF_TYPE_HW_CACHE:
PERF_TYPE_HW_CACHE: 0xEEEEEEEE00DDCCBB BB: hardware cache ID CC:
hardware cache op ID DD: hardware cache op result ID EEEEEEEE: PMU type
ID
When enabling a hardware event without specified pmu, such as, perf
stat -e cycles -a (use system-wide in this example), two events are
created automatically.
------------------------------------------------------------
perf_event_attr:
size 120
config 0x400000000
sample_type IDENTIFIER
read_format TOTAL_TIME_ENABLED|TOTAL_TIME_RUNNING
disabled 1
inherit 1
exclude_guest 1
------------------------------------------------------------
and
------------------------------------------------------------
perf_event_attr:
size 120
config 0x800000000
sample_type IDENTIFIER
read_format TOTAL_TIME_ENABLED|TOTAL_TIME_RUNNING
disabled 1
inherit 1
exclude_guest 1
------------------------------------------------------------
type 0 is PERF_TYPE_HARDWARE. 0x4 in 0x400000000 indicates it’s
cpu_core pmu. 0x8 in 0x800000000 indicates it’s cpu_atom pmu (atom pmu
type id is random).
The kernel creates cycles (0x400000000) on cpu0-cpu15 (core cpus), and
create cycles (0x800000000) on cpu16-cpu23 (atom cpus).
For perf-stat result, it displays two events:
Performance counter stats for 'system wide':
6,744,979 cpu_core/cycles/
1,965,552 cpu_atom/cycles/
The first cycles is core event, the second cycles is atom event.
THREAD MODE EXAMPLE:
perf-stat reports the scaled counts for hybrid event and with a
percentage displayed. The percentage is the event’s running
time/enabling time.
One example, triad_loop runs on cpu16 (atom core), while we can see the
scaled value for core cycles is 160,444,092 and the percentage is
0.47%.
perf stat -e cycles -- taskset -c 16 ./triad_loop
As previous, two events are created.
.ft C
perf_event_attr:
size 120
config 0x400000000
sample_type IDENTIFIER
read_format TOTAL_TIME_ENABLED|TOTAL_TIME_RUNNING
disabled 1
inherit 1
enable_on_exec 1
exclude_guest 1
.ft
and
.ft C
perf_event_attr:
size 120
config 0x800000000
sample_type IDENTIFIER
read_format TOTAL_TIME_ENABLED|TOTAL_TIME_RUNNING
disabled 1
inherit 1
enable_on_exec 1
exclude_guest 1
.ft
Performance counter stats for 'taskset -c 16 ./triad_loop':
233,066,666 cpu_core/cycles/ (0.43%)
604,097,080 cpu_atom/cycles/ (99.57%)
PERF-RECORD:
If there is no -e specified in perf record, on hybrid platform, it
creates two default cycles and adds them to event list. One is for
core, the other is for atom.
PERF-STAT:
If there is no -e specified in perf stat, on hybrid platform, besides
of software events, following events are created and added to event
list in order.
cpu_core/cycles/, cpu_atom/cycles/, cpu_core/instructions/,
cpu_atom/instructions/, cpu_core/branches/, cpu_atom/branches/,
cpu_core/branch-misses/, cpu_atom/branch-misses/
Of course, both perf-stat and perf-record support to enable hybrid
event with a specific pmu.
e.g. perf stat -e cpu_core/cycles/ perf stat -e cpu_atom/cycles/ perf
stat -e cpu_core/r1a/ perf stat -e cpu_atom/L1-icache-loads/ perf stat
-e cpu_core/cycles/,cpu_atom/instructions/ perf stat -e
{cpu_core/cycles/,cpu_core/instructions/}
But {cpu_core/cycles/,cpu_atom/instructions/} will return warning and
disable grouping, because the pmus in group are not matched (cpu_core
vs. cpu_atom).
SEE ALSO
perf-stat(1), perf-list(1), perf-intel-pt(1)
perf 12/18/2024 PERF-RECORD(1)
Generated by dwww version 1.14 on Thu Jan 23 05:38:10 CET 2025.