NAME
perf-report - Read perf.data (created by perf record) and display the profileSYNOPSIS
perf report [-i <file> | --input=file]
DESCRIPTION
This command displays the performance counter profile information recorded via perf record.OPTIONS
-i, --input=Input file name. (default: perf.data unless
stdin is a fifo)
Be more verbose. (show symbol address,
etc)
Do not show any warnings or messages.
(Suppress -v)
Show the number of samples for each
symbol
Show sample percentage for different cpu
modes.
Show per-thread event counters. The input data
file should be recorded with -s option.
Only consider symbols in these comms. CSV that
understands <file://filename> entries. This option will affect
the percentage of the overhead column. See --percentage for more info.
Only show events for given process ID (comma
separated list).
Only show events for given thread ID (comma
separated list).
Only consider symbols in these dsos. CSV that
understands <file://filename> entries. This option will affect
the percentage of the overhead column. See --percentage for more info.
Only consider these symbols. CSV that
understands <file://filename> entries. This option will affect
the percentage of the overhead column. See --percentage for more info.
Only show symbols that match (partially) with
this filter.
Only display entries resolved to a
symbol.
Sort histogram entries by given key(s) -
multiple keys can be specified in CSV format. Following sort keys are
available: pid, comm, dso, symbol, parent, cpu, socket, srcline, weight,
local_weight, cgroup_id, addr.
Each key has following meaning:
•comm: command (name) of the task which
can be read via /proc/<pid>/comm
•pid: command and tid of the task
•dso: name of library or module
executed at the time of sample
•dso_size: size of library or module
executed at the time of sample
•symbol: name of function executed at
the time of sample
•symbol_size: size of function executed
at the time of sample
•parent: name of function matched to
the parent regex filter. Unmatched entries are displayed as
"[other]".
•cpu: cpu number the task ran at the
time of sample
•socket: processor socket number the
task ran at the time of sample
•srcline: filename and line number
executed at the time of sample. The DWARF debugging info must be
provided.
•srcfile: file name of the source file
of the samples. Requires dwarf information.
•weight: Event specific weight, e.g.
memory latency or transaction abort cost. This is the global weight.
•local_weight: Local weight version of
the weight above.
•cgroup_id: ID derived from cgroup
namespace device and inode numbers.
•cgroup: cgroup pathname in the
cgroupfs.
•transaction: Transaction abort
flags.
•overhead: Overhead percentage of
sample
•overhead_sys: Overhead percentage of
sample running in system mode
•overhead_us: Overhead percentage of
sample running in user mode
•overhead_guest_sys: Overhead
percentage of sample running in system mode on guest machine
•overhead_guest_us: Overhead percentage
of sample running in user mode on guest machine
•sample: Number of sample
•period: Raw number of event count of
sample
•time: Separate the samples by time
stamp with the resolution specified by --time-quantum (default 100ms). Specify
with overhead and before it.
•code_page_size: the code page size of
sampled code address (ip)
•ins_lat: Instruction latency in core
cycles. This is the global instruction latency
•local_ins_lat: Local instruction
latency version
•p_stage_cyc: On powerpc, this presents
the number of cycles spent in a pipeline stage. And currently supported only
on powerpc.
•addr: (Full) virtual address of the
sampled instruction
By default, comm, dso and symbol keys are used. (i.e. --sort comm,dso,symbol)
If --branch-stack option is used, following sort keys are also available:
•dso_from: name of library or module
branched from
•dso_to: name of library or module
branched to
•symbol_from: name of function branched
from
•symbol_to: name of function branched
to
•srcline_from: source file and line
branched from
•srcline_to: source file and line
branched to
•mispredict: "N" for
predicted branch, "Y" for mispredicted branch
•in_tx: branch in TSX transaction
•abort: TSX transaction abort.
•cycles: Cycles in basic block
And default sort keys are changed to comm, dso_from, symbol_from, dso_to and symbol_to, see '--branch-stack'.
When the sort key symbol is specified, columns "IPC" and "IPC Coverage" are enabled automatically. Column "IPC" reports the average IPC per function and column "IPC coverage" reports the percentage of instructions with sampled IPC in this function. IPC means Instruction Per Cycle. If it's low, it indicates there may be a performance bottleneck when the function is executed, such as a memory access bottleneck. If a function has high overhead and low IPC, it's worth further analyzing it to optimize its performance.
If the --mem-mode option is used, the following sort keys are also available (incompatible with --branch-stack): symbol_daddr, dso_daddr, locked, tlb, mem, snoop, dcacheline, blocked.
•symbol_daddr: name of data symbol
being executed on at the time of sample
•dso_daddr: name of library or module
containing the data being executed on at the time of the sample
•locked: whether the bus was locked at
the time of the sample
•tlb: type of tlb access for the data
at the time of the sample
•mem: type of memory access for the
data at the time of the sample
•snoop: type of snoop (if any) for the
data at the time of the sample
•dcacheline: the cacheline the data
address is on at the time of the sample
•phys_daddr: physical address of data
being executed on at the time of sample
•data_page_size: the data page size of
data being executed on at the time of sample
•blocked: reason of blocked load access
for the data at the time of the sample
And the default sort keys are changed to local_weight, mem, sym, dso, symbol_daddr, dso_daddr, snoop, tlb, locked, blocked, local_ins_lat, see '--mem-mode'.
If the data file has tracepoint event(s), following (dynamic) sort keys are also available: trace, trace_fields, [<event>.]<field>[/raw]
•trace: pretty printed trace output in
a single column
•trace_fields: fields in tracepoints in
separate columns
•<field name>: optional event and
field name for a specific field
The last form consists of event and field names. If event name is omitted, it searches all events for matching field name. The matched field will be shown only for the event has the field. The event name supports substring match so user doesn't need to specify full subsystem and event name everytime. For example, 'sched:sched_switch' event can be shortened to 'switch' as long as it's not ambiguous. Also event can be specified by its index (starting from 1) preceded by the '%'. So '%1' is the first event, '%2' is the second, and so on.
The field name can have '/raw' suffix which disables pretty printing and shows raw field value like hex numbers. The --raw-trace option has the same effect for all dynamic sort keys.
The default sort keys are changed to 'trace' if all events in the data file are tracepoint.
Specify output field - multiple keys can be
specified in CSV format. Following fields are available: overhead,
overhead_sys, overhead_us, overhead_children, sample and period. Also it can
contain any sort key(s).
By default, every sort keys not specified in -F will be appended automatically.
If the keys starts with a prefix '+', then it will append the specified field(s) to the default field order. For example: perf report -F +period,sample.
A regex filter to identify parent. The parent is a caller of this function and searched through the callchain, thus it requires callchain information recorded. The pattern is in the extended regex format and defaults to "^sys_|^do_page_fault", see --sort parent.
Only display entries with parent-match.
Force each column width to the provided list,
for large terminal readability. 0 means no limit (default behavior).
Use a special separator character and
don’t pad with spaces, replacing all occurrences of this separator in
symbol names (and other output) with a . character, that thus
it’s the only non valid separator.
Dump raw trace in ASCII.
Disable raw trace ordering.
Display call chains using type, min percent threshold, print limit, call order, sort key, optional branch and value. Note that ordering is not fixed so any parameter can be given in an arbitrary order. One exception is the print_limit which should be preceded by threshold.
print_type can be either: - flat: single column, linear exposure of call chains. - graph: use a graph tree, displaying absolute overhead rates. (default) - fractal: like graph, but displays relative rates. Each branch of the tree is considered as a new profiled object. - folded: call chains are displayed in a line, separated by semicolons - none: disable call chain display.
threshold is a percentage value which specifies a minimum percent to be included in the output call graph. Default is 0.5 (%).
print_limit is only applied when stdio interface is used. It's to limit number of call graph entries in a single hist entry. Note that it needs to be given after threshold (but not necessarily consecutive). Default is 0 (unlimited).
order can be either: - callee: callee based call graph. - caller: inverted caller based call graph. Default is 'caller' when --children is used, otherwise 'callee'.
sort_key can be: - function: compare on functions (default) - address: compare on individual code addresses - srcline: compare on source filename and line number
branch can be: - branch: include last branch information in callgraph when available. Usually more convenient to use --branch-history for this.
value can be: - percent: display overhead percent (default) - period: display event period - count: display event count
Accumulate callchain of children to parent
entry so that then can show up in the output. The output will have a new
"Children" column and will be sorted on the data. It requires
callchains are recorded. See the ‘overhead calculation’ section
for more details. Enabled by default, disable with --no-children.
Set the stack depth limit when parsing the
callchain, anything beyond the specified depth will be ignored. This is a
trade-off between information loss and faster processing especially for
workloads that can have a very long callchain stack. Note that when using the
--itrace option the synthesized callchain size will override this value if the
synthesized callchain size is bigger.
Default: 127
alias for inverted caller based call
graph.
Ignore callees of the function(s) matching the
given regex. This has the effect of collecting the callers of each such
function into one place in the call-graph tree.
Pretty printing style. key: normal, raw
Use the stdio interface.
always, never or auto,
allowing configuring color output via the command line, in addition to via
"color.ui" .perfconfig. Use --stdio-color always to generate
color even when redirecting to a pipe or file. Using just --stdio-color
is equivalent to using always.
Use the TUI interface, that is integrated with
annotate and allows zooming into DSOs or threads, among other features. Use of
--tui requires a tty, if one is not present, as when piping to other commands,
the stdio interface is used.
Use the GTK2 interface.
vmlinux pathname
Ignore vmlinux files.
kallsyms pathname
Load module symbols. WARNING: This should only
be used with -k and a LIVE kernel.
Don’t do ownership validation.
Look for files with symbols relative to this
directory.
Only report samples for 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. Default is to report
samples on all CPUs.
Set disassembler style for objdump.
Interleave source code with assembly code.
Enabled by default, disable with --no-source.
Show raw instruction encoding of assembly
instructions.
Show a column with the sum of periods.
Display extended information about the
perf.data file. This adds information which may be very large and thus may
clutter the display. It currently includes: cpu and numa topology of the host
system.
Use the addresses of sampled taken branches
instead of the instruction address to build the histograms. To generate
meaningful output, the perf.data file must have been obtained using perf
record -b or perf record --branch-filter xxx where xxx is a branch filter
option. perf report is able to auto-detect whether a perf.data file contains
branch stacks and it will automatically switch to the branch view mode, unless
--no-branch-stack is used.
Add the addresses of sampled taken branches to
the callstack. This allows to examine the path the program took to each
sample. The data collection must have used -b (or -j) and -g.
Path to objdump binary.
Remove first N entries from source file path
names in executables and add PREFIX. This allows to display source code
compiled on systems with different file system layout.
Show event group information together. It
forces group output also if there are no groups defined in data file.
Sort the output by the event at the index n in
group. If n is invalid, sort by the first event. It can support multiple
groups with different amount of events. WARNING: This should be used on
grouped events.
Demangle symbol names to human readable form.
It’s enabled by default, disable with --no-demangle.
Demangle kernel symbol names to human readable
form (for C++ kernels).
Use the data addresses of samples in addition
to instruction addresses to build the histograms. To generate meaningful
output, the perf.data file must have been obtained using perf record -d -W and
using a special event -e cpu/mem-loads/p or -e cpu/mem-stores/p. See perf
mem for simpler access.
Do not show entries which have an overhead
under that percent. (Default: 0). Note that this option also sets the percent
limit (threshold) of callchains. However the default value of callchain
threshold is different than the default value of hist entries. Please see the
--call-graph option for details.
Determine how to display the overhead
percentage of filtered entries. Filters can be applied by --comms, --dsos
and/or --symbols options and Zoom operations on the TUI (thread, dso, etc).
"relative" means it's relative to filtered entries only so that the sum of shown entries will be always 100%. "absolute" means it retains the original value before and after the filter is applied.
Show header information in the perf.data file.
This includes various information like hostname, OS and perf version, cpu/mem
info, perf command line, event list and so on. Currently only --stdio output
supports this feature.
Show only perf.data header (forces
--stdio).
Only analyze samples within given time window:
<start>,<stop>. Times have the format seconds.nanoseconds. If
start is not given (i.e. time string is ,x.y) then analysis starts at
the beginning of the file. If stop time is not given (i.e. time string is
x.y,) then analysis goes to end of file. Multiple ranges can be
separated by spaces, which requires the argument to be quoted e.g. --time
"1234.567,1234.789 1235,"
Also support time percent with multiple time ranges. Time string is 'a%/n,b%/m,...' or 'a%-b%,c%-%d,...'.
For example: Select the second 10% time slice:
perf report --time 10%/2
Select from 0% to 10% time slice:
perf report --time 0%-10%
Select the first and second 10% time slices:
perf report --time 10%/1,10%/2
Select from 0% to 10% and 30% to 40% slices:
perf report --time 0%-10%,30%-40%
Only consider events after this event is
found.
This may be interesting to measure a workload only after some initialization phase is over, i.e. insert a perf probe at that point and then using this option with that probe.
Stop considering events after this event is
found.
Show the --switch-on/off events too. This has
no effect in perf report now but probably we’ll make the default
not to show the switch-on/off events on the --group mode and if there is only
one event besides the off/on ones, go straight to the histogram browser, just
like perf report with no events explicitly specified does.
Options for decoding instruction tracing data.
The options are:
i synthesize instructions events b synthesize branches events (branch misses for Arm SPE) c synthesize branches events (calls only) r synthesize branches events (returns only) x synthesize transactions events w synthesize ptwrite events p synthesize power events (incl. PSB events for Intel PT) o synthesize other events recorded due to the use of aux-output (refer to perf record) I synthesize interrupt or similar (asynchronous) events (e.g. Intel PT Event Trace) e synthesize error events d create a debug log f synthesize first level cache events m synthesize last level cache events M synthesize memory events t synthesize TLB events a synthesize remote access events g synthesize a call chain (use with i or x) G synthesize a call chain on existing event records l synthesize last branch entries (use with i or x) L synthesize last branch entries on existing event records s skip initial number of events q quicker (less detailed) decoding A approximate IPC Z prefer to ignore timestamps (so-called "timeless" decoding)
The default is all events i.e. the same as --itrace=ibxwpe, except for perf script where it is --itrace=ce
In addition, the period (default 100000, except for perf script where it is 1) for instructions events can be specified in units of:
i instructions t ticks ms milliseconds us microseconds ns nanoseconds (default)
Also the call chain size (default 16, max. 1024) for instructions or transactions events can be specified.
Also the number of last branch entries (default 64, max. 1024) for instructions or transactions events can be specified.
Similar to options g and l, size may also be specified for options G and L. On x86, note that G and L work poorly when data has been recorded with large PEBS. Refer linkperf:perf-intel-pt[1] man page for details.
It is also possible to skip events generated (instructions, branches, transactions, ptwrite, power) at the beginning. This is useful to ignore initialization code.
--itrace=i0nss1000000
skips the first million instructions.
The 'e' option may be followed by flags which affect what errors will or will not be reported. Each flag must be preceded by either '+' or '-'. The flags are: o overflow l trace data lost
If supported, the 'd' option may be followed by flags which affect what debug messages will or will not be logged. Each flag must be preceded by either '+' or '-'. The flags are: a all perf events e output only on errors (size configurable - see linkperf:perf-config[1]) o output to stdout
If supported, the 'q' option may be repeated to increase the effect.
To disable decoding entirely, use --no-itrace.
Show the full path for source files for
srcline output.
When multiple events are sampled, it may not
be needed to collect callgraphs for all of them. The sample sites are usually
nearby, and it’s enough to collect the callgraphs on a reference event.
So user can use "call-graph=no" event modifier to disable callgraph
for other events to reduce the overhead. However, perf report cannot show
callgraphs for the event which disable the callgraph. This option extends the
perf report to show reference callgraphs, which collected by reference event,
in no callgraph event.
Show callgraph with stitched LBRs, which may
have more complete callgraph. The perf.data file must have been obtained using
perf record --call-graph lbr. Disabled by default. In common cases with call
stack overflows, it can recreate better call stacks than the default lbr call
stack output. But this approach is not full proof. There can be cases where it
creates incorrect call stacks from incorrect matches. The known limitations
include exception handing such as setjmp/longjmp will have calls/returns not
match.
Only report the samples on the processor
socket that match with this filter
Save N individual samples for each histogram
entry to show context in perf report tui browser.
When displaying traceevent output, do not use
print fmt or plugins.
Enable hierarchical output.
If a callgraph address belongs to an inlined
function, the inline stack will be printed. Each entry is function name or
file/line. Enabled by default, disable with --no-inline.
Show --tasks output plus mmap information in a
format similar to /proc/<PID>/maps.
Please note that not all mmaps are stored, options affecting which ones are include 'perf record --data', for instance.
Show time stamps in nanoseconds.
Display overall events statistics without any
further processing. (like the one at the end of the perf report -D
command)
Display monitored tasks stored in perf data.
Displaying pid/tid/ppid plus the command string aligned to distinguish parent
and child tasks.
Set annotation percent type from following
choices: global-period, local-period, global-hits, local-hits
The local/global keywords set if the percentage is computed in the scope of the function (local) or the whole data (global). The period/hits keywords set the base the percentage is computed on - the samples period or the number of samples (hits).
Configure time quantum for time sort key.
Default 100ms. Accepts s, us, ms, ns units.
When --total-cycles is specified, it supports
sorting for all blocks by Sampled Cycles%. This is useful to
concentrate on the globally hottest blocks. In output, there are some new
columns:
'Sampled Cycles%' - block sampled cycles aggregation / total sampled cycles 'Sampled Cycles' - block sampled cycles aggregation 'Avg Cycles%' - block average sampled cycles / sum of total block average sampled cycles 'Avg Cycles' - block average sampled cycles
Do not print 0 results in the --stat
output.
OVERHEAD CALCULATION
The overhead can be shown in two columns as Children and Self when perf collects callchains. The self overhead is simply calculated by adding all period values of the entry - usually a function (symbol). This is the value that perf shows traditionally and sum of all the self overhead values should be 100%.void foo(void) { /* do something */ } void bar(void) { /* do something */ foo(); } int main(void) { bar() return 0; }
Overhead Symbol ........ ..................... 60.00% foo | --- foo bar main __libc_start_main 40.00% bar | --- bar main __libc_start_main
Children Self Symbol ........ ........ .................... 100.00% 0.00% __libc_start_main | --- __libc_start_main 100.00% 0.00% main | --- main __libc_start_main 100.00% 40.00% bar | --- bar main __libc_start_main 60.00% 60.00% foo | --- foo bar main __libc_start_main
SEE ALSO
perf-stat(1), perf-annotate(1), perf-record(1), perf-intel-pt(1)2024-06-21 | perf |