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--prefix=PREFIX::
165--prefix-strip=N::
166        Remove first N entries from source file path names in executables
167        and add PREFIX. This allows to display source code compiled on systems
168        with different file system layout.
169
170--source::
171	Interleave source code with assembly code. Enabled by default,
172	disable with --no-source.
173
174--asm-raw::
175	Show raw instruction encoding of assembly instructions.
176
177-g::
178	Enables call-graph (stack chain/backtrace) recording.
179
180--call-graph [mode,type,min[,limit],order[,key][,branch]]::
181	Setup and enable call-graph (stack chain/backtrace) recording,
182	implies -g.  See `--call-graph` section in perf-record and
183	perf-report man pages for details.
184
185--children::
186	Accumulate callchain of children to parent entry so that then can
187	show up in the output.  The output will have a new "Children" column
188	and will be sorted on the data.  It requires -g/--call-graph option
189	enabled.  See the `overhead calculation' section for more details.
190	Enabled by default, disable with --no-children.
191
192--max-stack::
193	Set the stack depth limit when parsing the callchain, anything
194	beyond the specified depth will be ignored. This is a trade-off
195	between information loss and faster processing especially for
196	workloads that can have a very long callchain stack.
197
198	Default: /proc/sys/kernel/perf_event_max_stack when present, 127 otherwise.
199
200--ignore-callees=<regex>::
201        Ignore callees of the function(s) matching the given regex.
202        This has the effect of collecting the callers of each such
203        function into one place in the call-graph tree.
204
205--percent-limit::
206	Do not show entries which have an overhead under that percent.
207	(Default: 0).
208
209--percentage::
210	Determine how to display the overhead percentage of filtered entries.
211	Filters can be applied by --comms, --dsos and/or --symbols options and
212	Zoom operations on the TUI (thread, dso, etc).
213
214	"relative" means it's relative to filtered entries only so that the
215	sum of shown entries will be always 100%. "absolute" means it retains
216	the original value before and after the filter is applied.
217
218-w::
219--column-widths=<width[,width...]>::
220	Force each column width to the provided list, for large terminal
221	readability.  0 means no limit (default behavior).
222
223--proc-map-timeout::
224	When processing pre-existing threads /proc/XXX/mmap, it may take
225	a long time, because the file may be huge. A time out is needed
226	in such cases.
227	This option sets the time out limit. The default value is 500 ms.
228
229
230-b::
231--branch-any::
232	Enable taken branch stack sampling. Any type of taken branch may be sampled.
233	This is a shortcut for --branch-filter any. See --branch-filter for more infos.
234
235-j::
236--branch-filter::
237	Enable taken branch stack sampling. Each sample captures a series of consecutive
238	taken branches. The number of branches captured with each sample depends on the
239	underlying hardware, the type of branches of interest, and the executed code.
240	It is possible to select the types of branches captured by enabling filters.
241	For a full list of modifiers please see the perf record manpage.
242
243	The option requires at least one branch type among any, any_call, any_ret, ind_call, cond.
244	The privilege levels may be omitted, in which case, the privilege levels of the associated
245	event are applied to the branch filter. Both kernel (k) and hypervisor (hv) privilege
246	levels are subject to permissions.  When sampling on multiple events, branch stack sampling
247	is enabled for all the sampling events. The sampled branch type is the same for all events.
248	The various filters must be specified as a comma separated list: --branch-filter any_ret,u,k
249	Note that this feature may not be available on all processors.
250
251--raw-trace::
252	When displaying traceevent output, do not use print fmt or plugins.
253
254--hierarchy::
255	Enable hierarchy output.
256
257--overwrite::
258	Enable this to use just the most recent records, which helps in high core count
259	machines such as Knights Landing/Mill, but right now is disabled by default as
260	the pausing used in this technique is leading to loss of metadata events such
261	as PERF_RECORD_MMAP which makes 'perf top' unable to resolve samples, leading
262	to lots of unknown samples appearing on the UI. Enable this if you are in such
263	machines and profiling a workload that doesn't creates short lived threads and/or
264	doesn't uses many executable mmap operations. Work is being planed to solve
265	this situation, till then, this will remain disabled by default.
266
267--force::
268	Don't do ownership validation.
269
270--num-thread-synthesize::
271	The number of threads to run when synthesizing events for existing processes.
272	By default, the number of threads equals to the number of online CPUs.
273
274--namespaces::
275	Record events of type PERF_RECORD_NAMESPACES and display it with the
276	'cgroup_id' sort key.
277
278-G name::
279--cgroup name::
280monitor only in the container (cgroup) called "name". This option is available only
281in per-cpu mode. The cgroup filesystem must be mounted. All threads belonging to
282container "name" are monitored when they run on the monitored CPUs. Multiple cgroups
283can be provided. Each cgroup is applied to the corresponding event, i.e., first cgroup
284to first event, second cgroup to second event and so on. It is possible to provide
285an empty cgroup (monitor all the time) using, e.g., -G foo,,bar. Cgroups must have
286corresponding events, i.e., they always refer to events defined earlier on the command
287line. If the user wants to track multiple events for a specific cgroup, the user can
288use '-e e1 -e e2 -G foo,foo' or just use '-e e1 -e e2 -G foo'.
289
290--all-cgroups::
291	Record events of type PERF_RECORD_CGROUP and display it with the
292	'cgroup' sort key.
293
294--switch-on EVENT_NAME::
295	Only consider events after this event is found.
296
297	E.g.:
298
299           Find out where broadcast packets are handled
300
301		perf probe -L icmp_rcv
302
303	   Insert a probe there:
304
305		perf probe icmp_rcv:59
306
307	   Start perf top and ask it to only consider the cycles events when a
308           broadcast packet arrives This will show a menu with two entries and
309           will start counting when a broadcast packet arrives:
310
311		perf top -e cycles,probe:icmp_rcv --switch-on=probe:icmp_rcv
312
313	   Alternatively one can ask for a group and then two overhead columns
314           will appear, the first for cycles and the second for the switch-on event.
315
316		perf top -e '{cycles,probe:icmp_rcv}' --switch-on=probe:icmp_rcv
317
318	This may be interesting to measure a workload only after some initialization
319	phase is over, i.e. insert a perf probe at that point and use the above
320	examples replacing probe:icmp_rcv with the just-after-init probe.
321
322--switch-off EVENT_NAME::
323	Stop considering events after this event is found.
324
325--show-on-off-events::
326	Show the --switch-on/off events too. This has no effect in 'perf top' now
327	but probably we'll make the default not to show the switch-on/off events
328        on the --group mode and if there is only one event besides the off/on ones,
329	go straight to the histogram browser, just like 'perf top' with no events
330	explicitly specified does.
331
332--stitch-lbr::
333	Show callgraph with stitched LBRs, which may have more complete
334	callgraph. The option must be used with --call-graph lbr recording.
335	Disabled by default. In common cases with call stack overflows,
336	it can recreate better call stacks than the default lbr call stack
337	output. But this approach is not full proof. There can be cases
338	where it creates incorrect call stacks from incorrect matches.
339	The known limitations include exception handing such as
340	setjmp/longjmp will have calls/returns not match.
341
342ifdef::HAVE_LIBPFM[]
343--pfm-events events::
344Select a PMU event using libpfm4 syntax (see http://perfmon2.sf.net)
345including support for event filters. For example '--pfm-events
346inst_retired:any_p:u:c=1:i'. More than one event can be passed to the
347option using the comma separator. Hardware events and generic hardware
348events cannot be mixed together. The latter must be used with the -e
349option. The -e option and this one can be mixed and matched.  Events
350can be grouped using the {} notation.
351endif::HAVE_LIBPFM[]
352
353INTERACTIVE PROMPTING KEYS
354--------------------------
355
356[d]::
357	Display refresh delay.
358
359[e]::
360	Number of entries to display.
361
362[E]::
363	Event to display when multiple counters are active.
364
365[f]::
366	Profile display filter (>= hit count).
367
368[F]::
369	Annotation display filter (>= % of total).
370
371[s]::
372	Annotate symbol.
373
374[S]::
375	Stop annotation, return to full profile display.
376
377[K]::
378	Hide kernel symbols.
379
380[U]::
381	Hide user symbols.
382
383[z]::
384	Toggle event count zeroing across display updates.
385
386[qQ]::
387	Quit.
388
389Pressing any unmapped key displays a menu, and prompts for input.
390
391include::callchain-overhead-calculation.txt[]
392
393SEE ALSO
394--------
395linkperf:perf-stat[1], linkperf:perf-list[1], linkperf:perf-report[1]
396