1perf-top(1)
2===========
3
4NAME
5----
6perf-top - System profiling tool.
7
8SYNOPSIS
9--------
10[verse]
11'perf top' [-e <EVENT> | --event=EVENT] [<options>]
12
13DESCRIPTION
14-----------
15This command generates and displays a performance counter profile in real time.
16
17
18OPTIONS
19-------
20-a::
21--all-cpus::
22        System-wide collection.  (default)
23
24-c <count>::
25--count=<count>::
26	Event period to sample.
27
28-C <cpu-list>::
29--cpu=<cpu>::
30Monitor only on the list of CPUs provided. Multiple CPUs can be provided as a
31comma-separated list with no space: 0,1. Ranges of CPUs are specified with -: 0-2.
32Default is to monitor all CPUS.
33
34-d <seconds>::
35--delay=<seconds>::
36	Number of seconds to delay between refreshes.
37
38-e <event>::
39--event=<event>::
40	Select the PMU event. Selection can be a symbolic event name
41	(use 'perf list' to list all events) or a raw PMU event in the form
42	of rN where N is a hexadecimal value that represents the raw register
43	encoding with the layout of the event control registers as described
44	by entries in /sys/bus/event_source/devices/cpu/format/*.
45
46-E <entries>::
47--entries=<entries>::
48	Display this many functions.
49
50-f <count>::
51--count-filter=<count>::
52	Only display functions with more events than this.
53
54--group-sort-idx::
55	Sort the output by the event at the index n in group. If n is invalid,
56	sort by the first event. It can support multiple groups with different
57	amount of events. WARNING: This should be used on grouped events.
58
59-F <freq>::
60--freq=<freq>::
61	Profile at this frequency. Use 'max' to use the currently maximum
62	allowed frequency, i.e. the value in the kernel.perf_event_max_sample_rate
63	sysctl.
64
65-i::
66--inherit::
67	Child tasks do not inherit counters.
68
69-k <path>::
70--vmlinux=<path>::
71	Path to vmlinux.  Required for annotation functionality.
72
73--ignore-vmlinux::
74	Ignore vmlinux files.
75
76--kallsyms=<file>::
77	kallsyms pathname
78
79-m <pages>::
80--mmap-pages=<pages>::
81	Number of mmap data pages (must be a power of two) or size
82	specification with appended unit character - B/K/M/G. The
83	size is rounded up to have nearest pages power of two value.
84
85-p <pid>::
86--pid=<pid>::
87	Profile events on existing Process ID (comma separated list).
88
89-t <tid>::
90--tid=<tid>::
91        Profile events on existing thread ID (comma separated list).
92
93-u::
94--uid=::
95        Record events in threads owned by uid. Name or number.
96
97-r <priority>::
98--realtime=<priority>::
99	Collect data with this RT SCHED_FIFO priority.
100
101--sym-annotate=<symbol>::
102        Annotate this symbol.
103
104-K::
105--hide_kernel_symbols::
106        Hide kernel symbols.
107
108-U::
109--hide_user_symbols::
110        Hide user symbols.
111
112--demangle-kernel::
113        Demangle kernel symbols.
114
115-D::
116--dump-symtab::
117        Dump the symbol table used for profiling.
118
119-v::
120--verbose::
121	Be more verbose (show counter open errors, etc).
122
123-z::
124--zero::
125	Zero history across display updates.
126
127-s::
128--sort::
129	Sort by key(s): pid, comm, dso, symbol, parent, srcline, weight,
130	local_weight, abort, in_tx, transaction, overhead, sample, period.
131	Please see description of --sort in the perf-report man page.
132
133--fields=::
134	Specify output field - multiple keys can be specified in CSV format.
135	Following fields are available:
136	overhead, overhead_sys, overhead_us, overhead_children, sample and period.
137	Also it can contain any sort key(s).
138
139	By default, every sort keys not specified in --field will be appended
140	automatically.
141
142-n::
143--show-nr-samples::
144	Show a column with the number of samples.
145
146--show-total-period::
147	Show a column with the sum of periods.
148
149--dsos::
150	Only consider symbols in these dsos.  This option will affect the
151	percentage of the overhead column.  See --percentage for more info.
152
153--comms::
154	Only consider symbols in these comms.  This option will affect the
155	percentage of the overhead column.  See --percentage for more info.
156
157--symbols::
158	Only consider these symbols.  This option will affect the
159	percentage of the overhead column.  See --percentage for more info.
160
161-M::
162--disassembler-style=:: Set disassembler style for objdump.
163
164--addr2line=<path>::
165        Path to addr2line binary.
166
167--objdump=<path>::
168        Path to objdump binary.
169
170--prefix=PREFIX::
171--prefix-strip=N::
172        Remove first N entries from source file path names in executables
173        and add PREFIX. This allows to display source code compiled on systems
174        with different file system layout.
175
176--source::
177	Interleave source code with assembly code. Enabled by default,
178	disable with --no-source.
179
180--asm-raw::
181	Show raw instruction encoding of assembly instructions.
182
183-g::
184	Enables call-graph (stack chain/backtrace) recording.
185
186--call-graph [mode,type,min[,limit],order[,key][,branch]]::
187	Setup and enable call-graph (stack chain/backtrace) recording,
188	implies -g.  See `--call-graph` section in perf-record and
189	perf-report man pages for details.
190
191--children::
192	Accumulate callchain of children to parent entry so that then can
193	show up in the output.  The output will have a new "Children" column
194	and will be sorted on the data.  It requires -g/--call-graph option
195	enabled.  See the `overhead calculation' section for more details.
196	Enabled by default, disable with --no-children.
197
198--max-stack::
199	Set the stack depth limit when parsing the callchain, anything
200	beyond the specified depth will be ignored. This is a trade-off
201	between information loss and faster processing especially for
202	workloads that can have a very long callchain stack.
203
204	Default: /proc/sys/kernel/perf_event_max_stack when present, 127 otherwise.
205
206--ignore-callees=<regex>::
207        Ignore callees of the function(s) matching the given regex.
208        This has the effect of collecting the callers of each such
209        function into one place in the call-graph tree.
210
211--percent-limit::
212	Do not show entries which have an overhead under that percent.
213	(Default: 0).
214
215--percentage::
216	Determine how to display the overhead percentage of filtered entries.
217	Filters can be applied by --comms, --dsos and/or --symbols options and
218	Zoom operations on the TUI (thread, dso, etc).
219
220	"relative" means it's relative to filtered entries only so that the
221	sum of shown entries will be always 100%. "absolute" means it retains
222	the original value before and after the filter is applied.
223
224-w::
225--column-widths=<width[,width...]>::
226	Force each column width to the provided list, for large terminal
227	readability.  0 means no limit (default behavior).
228
229--proc-map-timeout::
230	When processing pre-existing threads /proc/XXX/mmap, it may take
231	a long time, because the file may be huge. A time out is needed
232	in such cases.
233	This option sets the time out limit. The default value is 500 ms.
234
235
236-b::
237--branch-any::
238	Enable taken branch stack sampling. Any type of taken branch may be sampled.
239	This is a shortcut for --branch-filter any. See --branch-filter for more infos.
240
241-j::
242--branch-filter::
243	Enable taken branch stack sampling. Each sample captures a series of consecutive
244	taken branches. The number of branches captured with each sample depends on the
245	underlying hardware, the type of branches of interest, and the executed code.
246	It is possible to select the types of branches captured by enabling filters.
247	For a full list of modifiers please see the perf record manpage.
248
249	The option requires at least one branch type among any, any_call, any_ret, ind_call, cond.
250	The privilege levels may be omitted, in which case, the privilege levels of the associated
251	event are applied to the branch filter. Both kernel (k) and hypervisor (hv) privilege
252	levels are subject to permissions.  When sampling on multiple events, branch stack sampling
253	is enabled for all the sampling events. The sampled branch type is the same for all events.
254	The various filters must be specified as a comma separated list: --branch-filter any_ret,u,k
255	Note that this feature may not be available on all processors.
256
257--branch-history::
258	Add the addresses of sampled taken branches to the callstack.
259	This allows to examine the path the program took to each sample.
260
261--raw-trace::
262	When displaying traceevent output, do not use print fmt or plugins.
263
264--hierarchy::
265	Enable hierarchy output.
266
267--overwrite::
268	Enable this to use just the most recent records, which helps in high core count
269	machines such as Knights Landing/Mill, but right now is disabled by default as
270	the pausing used in this technique is leading to loss of metadata events such
271	as PERF_RECORD_MMAP which makes 'perf top' unable to resolve samples, leading
272	to lots of unknown samples appearing on the UI. Enable this if you are in such
273	machines and profiling a workload that doesn't creates short lived threads and/or
274	doesn't uses many executable mmap operations. Work is being planed to solve
275	this situation, till then, this will remain disabled by default.
276
277--force::
278	Don't do ownership validation.
279
280--num-thread-synthesize::
281	The number of threads to run when synthesizing events for existing processes.
282	By default, the number of threads equals to the number of online CPUs.
283
284--namespaces::
285	Record events of type PERF_RECORD_NAMESPACES and display it with the
286	'cgroup_id' sort key.
287
288-G name::
289--cgroup name::
290monitor only in the container (cgroup) called "name". This option is available only
291in per-cpu mode. The cgroup filesystem must be mounted. All threads belonging to
292container "name" are monitored when they run on the monitored CPUs. Multiple cgroups
293can be provided. Each cgroup is applied to the corresponding event, i.e., first cgroup
294to first event, second cgroup to second event and so on. It is possible to provide
295an empty cgroup (monitor all the time) using, e.g., -G foo,,bar. Cgroups must have
296corresponding events, i.e., they always refer to events defined earlier on the command
297line. If the user wants to track multiple events for a specific cgroup, the user can
298use '-e e1 -e e2 -G foo,foo' or just use '-e e1 -e e2 -G foo'.
299
300--all-cgroups::
301	Record events of type PERF_RECORD_CGROUP and display it with the
302	'cgroup' sort key.
303
304--switch-on EVENT_NAME::
305	Only consider events after this event is found.
306
307	E.g.:
308
309           Find out where broadcast packets are handled
310
311		perf probe -L icmp_rcv
312
313	   Insert a probe there:
314
315		perf probe icmp_rcv:59
316
317	   Start perf top and ask it to only consider the cycles events when a
318           broadcast packet arrives This will show a menu with two entries and
319           will start counting when a broadcast packet arrives:
320
321		perf top -e cycles,probe:icmp_rcv --switch-on=probe:icmp_rcv
322
323	   Alternatively one can ask for a group and then two overhead columns
324           will appear, the first for cycles and the second for the switch-on event.
325
326		perf top -e '{cycles,probe:icmp_rcv}' --switch-on=probe:icmp_rcv
327
328	This may be interesting to measure a workload only after some initialization
329	phase is over, i.e. insert a perf probe at that point and use the above
330	examples replacing probe:icmp_rcv with the just-after-init probe.
331
332--switch-off EVENT_NAME::
333	Stop considering events after this event is found.
334
335--show-on-off-events::
336	Show the --switch-on/off events too. This has no effect in 'perf top' now
337	but probably we'll make the default not to show the switch-on/off events
338        on the --group mode and if there is only one event besides the off/on ones,
339	go straight to the histogram browser, just like 'perf top' with no events
340	explicitly specified does.
341
342--stitch-lbr::
343	Show callgraph with stitched LBRs, which may have more complete
344	callgraph. The option must be used with --call-graph lbr recording.
345	Disabled by default. In common cases with call stack overflows,
346	it can recreate better call stacks than the default lbr call stack
347	output. But this approach is not foolproof. There can be cases
348	where it creates incorrect call stacks from incorrect matches.
349	The known limitations include exception handing such as
350	setjmp/longjmp will have calls/returns not match.
351
352ifdef::HAVE_LIBPFM[]
353--pfm-events events::
354Select a PMU event using libpfm4 syntax (see http://perfmon2.sf.net)
355including support for event filters. For example '--pfm-events
356inst_retired:any_p:u:c=1:i'. More than one event can be passed to the
357option using the comma separator. Hardware events and generic hardware
358events cannot be mixed together. The latter must be used with the -e
359option. The -e option and this one can be mixed and matched.  Events
360can be grouped using the {} notation.
361endif::HAVE_LIBPFM[]
362
363INTERACTIVE PROMPTING KEYS
364--------------------------
365
366[d]::
367	Display refresh delay.
368
369[e]::
370	Number of entries to display.
371
372[E]::
373	Event to display when multiple counters are active.
374
375[f]::
376	Profile display filter (>= hit count).
377
378[F]::
379	Annotation display filter (>= % of total).
380
381[s]::
382	Annotate symbol.
383
384[S]::
385	Stop annotation, return to full profile display.
386
387[K]::
388	Hide kernel symbols.
389
390[U]::
391	Hide user symbols.
392
393[z]::
394	Toggle event count zeroing across display updates.
395
396[qQ]::
397	Quit.
398
399Pressing any unmapped key displays a menu, and prompts for input.
400
401include::callchain-overhead-calculation.txt[]
402
403SEE ALSO
404--------
405linkperf:perf-stat[1], linkperf:perf-list[1], linkperf:perf-report[1]
406