perf-report(1)
NAME
perf-report - Read perf.data (created by perf record) and display the profile
SYNOPSIS
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)
-v, --verbose
Be more verbose. (show symbol address, etc)
-n, --show-nr-samples
Show the number of samples for each symbol
--show-cpu-utilization
Show sample percentage for different cpu modes.
-T, --threads
Show per-thread event counters. The input data file should be
recorded with -s option.
-c, --comms=
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.
--pid=
Only show events for given process ID (comma separated list).
--tid=
Only show events for given thread ID (comma separated list).
-d, --dsos=
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.
-S, --symbols=
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.
--symbol-filter=
Only show symbols that match (partially) with this filter.
-U, --hide-unresolved
Only display entries resolved to a symbol.
-s, --sort=
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.
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
* symbol: name 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 same. 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.
* 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
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'.
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.
* 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
And the default sort keys are changed to local_weight, mem, sym, dso,
symbol_daddr, dso_daddr, snoop, tlb, locked, 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.
-F, --fields=
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.
-p, --parent=<regex>
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 exteneded
regex format and defaults to "^sys_|^do_page_fault", see --sort
parent.
-x, --exclude-other
Only display entries with parent-match.
-w, --column-widths=<width[,width...]>
Force each column width to the provided list, for large terminal
readability. 0 means no limit (default behavior).
-t, --field-separator=
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.
-D, --dump-raw-trace
Dump raw trace in ASCII.
-g,
--call-graph=<print_type,threshold[,print_limit],order,sort_key[,branch],value>
Display call chains using type, min percent threshold, print limit,
call order, sort key, optional branch and value. Note that ordering
of parameters is not fixed so any parement can be given in an
arbitraty 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
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: diplay overhead percent (default)
- period: display event period
- count: display event count
--children
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.
--max-stack
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
-G, --inverted
alias for inverted caller based call graph.
--ignore-callees=<regex>
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=<key>
Pretty printing style. key: normal, raw
--stdio
Use the stdio interface.
--stdio-color
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.
--tui
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.
--gtk
Use the GTK2 interface.
-k, --vmlinux=<file>
vmlinux pathname
--kallsyms=<file>
kallsyms pathname
-m, --modules
Load module symbols. WARNING: This should only be used with -k and
a LIVE kernel.
-f, --force
Don't do ownership validation.
--symfs=<directory>
Look for files with symbols relative to this directory.
-C, --cpu
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.
-M, --disassembler-style=
Set disassembler style for objdump.
--source
Interleave source code with assembly code. Enabled by default,
disable with --no-source.
--asm-raw
Show raw instruction encoding of assembly instructions.
--show-total-period
Show a column with the sum of periods.
-I, --show-info
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.
-b, --branch-stack
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.
--branch-history
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.
--objdump=<path>
Path to objdump binary.
--group
Show event group information together.
--demangle
Demangle symbol names to human readable form. It's enabled by
default, disable with --no-demangle.
--demangle-kernel
Demangle kernel symbol names to human readable form (for C++
kernels).
--mem-mode
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/ or -e cpu/mem-stores/.
See perf mem for simpler access.
--percent-limit
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.
--percentage
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.
--header
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.
--header-only
Show only perf.data header (forces --stdio).
--itrace
Options for decoding instruction tracing data. The options are:
i synthesize instructions events
b synthesize branches events
c synthesize branches events (calls only)
r synthesize branches events (returns only)
x synthesize transactions events
e synthesize error events
d create a debug log
g synthesize a call chain (use with i or x)
l synthesize last branch entries (use with i or x)
s skip initial number of events
The default is all events i.e. the same as --itrace=ibxe
In addition, the period (default 100000) 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.
It is also possible to skip events generated (instructions, branches, transactions)
at the beginning. This is useful to ignore initialization code.
--itrace=i0nss1000000
skips the first million instructions.
To disable decoding entirely, use --no-itrace.
--full-source-path
Show the full path for source files for srcline output.
--show-ref-call-graph
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.
--socket-filter
Only report the samples on the processor socket that match with
this filter
--raw-trace
When displaying traceevent output, do not use print fmt or plugins.
--hierarchy
Enable hierarchical 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%.
The children overhead is calculated by adding all period values of the
child functions so that it can show the total overhead of the higher
level functions even if they don't directly execute much. Children here
means functions that are called from another (parent) function.
It might be confusing that the sum of all the children overhead values
exceeds 100% since each of them is already an accumulation of self
overhead of its child functions. But with this enabled, users can find
which function has the most overhead even if samples are spread over
the children.
Consider the following example; there are three functions like below.
.ft C
void foo(void) {
/* do something */
}
void bar(void) {
/* do something */
foo();
}
int main(void) {
bar()
return 0;
}
.ft
In this case foo is a child of bar, and bar is an immediate child of
main so foo also is a child of main. In other words, main is a parent
of foo and bar, and bar is a parent of foo.
Suppose all samples are recorded in foo and bar only. When it's
recorded with callchains the output will show something like below in
the usual (self-overhead-only) output of perf report:
.ft C
Overhead Symbol
........ .....................
60.00% foo
|
--- foo
bar
main
__libc_start_main
40.00% bar
|
--- bar
main
__libc_start_main
.ft
When the --children option is enabled, the self overhead values of
child functions (i.e. foo and bar) are added to the parents to
calculate the children overhead. In this case the report could be
displayed as:
.ft C
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
.ft
In the above output, the self overhead of foo (60%) was add to the
children overhead of bar, main and __libc_start_main. Likewise, the
self overhead of bar (40%) was added to the children overhead of main
and \_\_libc_start_main.
So \_\_libc_start_main and main are shown first since they have same
(100%) children overhead (even though they have zero self overhead) and
they are the parents of foo and bar.
Since v3.16 the children overhead is shown by default and the output is
sorted by its values. The children overhead is disabled by specifying
--no-children option on the command line or by adding report.children =
false or top.children = false in the perf config file.
SEE ALSO
perf-stat(1), perf-annotate(1)
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