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linux
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 explicitely 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]