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