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