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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-G name::
281--cgroup name::
282monitor only in the container (cgroup) called "name". This option is available only
283in per-cpu mode. The cgroup filesystem must be mounted. All threads belonging to
284container "name" are monitored when they run on the monitored CPUs. Multiple cgroups
285can be provided. Each cgroup is applied to the corresponding event, i.e., first cgroup
286to first event, second cgroup to second event and so on. It is possible to provide
287an empty cgroup (monitor all the time) using, e.g., -G foo,,bar. Cgroups must have
288corresponding events, i.e., they always refer to events defined earlier on the command
289line. If the user wants to track multiple events for a specific cgroup, the user can
290use '-e e1 -e e2 -G foo,foo' or just use '-e e1 -e e2 -G foo'.
291
292--all-cgroups::
293 Record events of type PERF_RECORD_CGROUP and display it with the
294 'cgroup' sort key.
295
296--switch-on EVENT_NAME::
297 Only consider events after this event is found.
298
299 E.g.:
300
301 Find out where broadcast packets are handled
302
303 perf probe -L icmp_rcv
304
305 Insert a probe there:
306
307 perf probe icmp_rcv:59
308
309 Start perf top and ask it to only consider the cycles events when a
310 broadcast packet arrives This will show a menu with two entries and
311 will start counting when a broadcast packet arrives:
312
313 perf top -e cycles,probe:icmp_rcv --switch-on=probe:icmp_rcv
314
315 Alternatively one can ask for --group and then two overhead columns
316 will appear, the first for cycles and the second for the switch-on event.
317
318 perf top --group -e cycles,probe:icmp_rcv --switch-on=probe:icmp_rcv
319
320 This may be interesting to measure a workload only after some initialization
321 phase is over, i.e. insert a perf probe at that point and use the above
322 examples replacing probe:icmp_rcv with the just-after-init probe.
323
324--switch-off EVENT_NAME::
325 Stop considering events after this event is found.
326
327--show-on-off-events::
328 Show the --switch-on/off events too. This has no effect in 'perf top' now
329 but probably we'll make the default not to show the switch-on/off events
330 on the --group mode and if there is only one event besides the off/on ones,
331 go straight to the histogram browser, just like 'perf top' with no events
332 explicitly specified does.
333
334--stitch-lbr::
335 Show callgraph with stitched LBRs, which may have more complete
336 callgraph. The option must be used with --call-graph lbr recording.
337 Disabled by default. In common cases with call stack overflows,
338 it can recreate better call stacks than the default lbr call stack
339 output. But this approach is not full proof. There can be cases
340 where it creates incorrect call stacks from incorrect matches.
341 The known limitations include exception handing such as
342 setjmp/longjmp will have calls/returns not match.
343
344ifdef::HAVE_LIBPFM[]
345--pfm-events events::
346Select a PMU event using libpfm4 syntax (see http://perfmon2.sf.net)
347including support for event filters. For example '--pfm-events
348inst_retired:any_p:u:c=1:i'. More than one event can be passed to the
349option using the comma separator. Hardware events and generic hardware
350events cannot be mixed together. The latter must be used with the -e
351option. The -e option and this one can be mixed and matched. Events
352can be grouped using the {} notation.
353endif::HAVE_LIBPFM[]
354
355INTERACTIVE PROMPTING KEYS
356--------------------------
357
358[d]::
359 Display refresh delay.
360
361[e]::
362 Number of entries to display.
363
364[E]::
365 Event to display when multiple counters are active.
366
367[f]::
368 Profile display filter (>= hit count).
369
370[F]::
371 Annotation display filter (>= % of total).
372
373[s]::
374 Annotate symbol.
375
376[S]::
377 Stop annotation, return to full profile display.
378
379[K]::
380 Hide kernel symbols.
381
382[U]::
383 Hide user symbols.
384
385[z]::
386 Toggle event count zeroing across display updates.
387
388[qQ]::
389 Quit.
390
391Pressing any unmapped key displays a menu, and prompts for input.
392
393include::callchain-overhead-calculation.txt[]
394
395SEE ALSO
396--------
397linkperf:perf-stat[1], linkperf:perf-list[1], linkperf:perf-report[1]
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-H::
265--hierarchy::
266 Enable hierarchical output. In the hierarchy mode, each sort key groups
267 samples based on the criteria and then sub-divide it using the lower
268 level sort key.
269
270 For example, in normal output:
271
272 perf report -s dso,sym
273 #
274 # Overhead Shared Object Symbol
275 # ........ ................. ...........
276 50.00% [kernel.kallsyms] [k] kfunc1
277 20.00% perf [.] foo
278 15.00% [kernel.kallsyms] [k] kfunc2
279 10.00% perf [.] bar
280 5.00% libc.so [.] libcall
281
282 In hierarchy output:
283
284 perf report -s dso,sym --hierarchy
285 #
286 # Overhead Shared Object / Symbol
287 # .......... ......................
288 65.00% [kernel.kallsyms]
289 50.00% [k] kfunc1
290 15.00% [k] kfunc2
291 30.00% perf
292 20.00% [.] foo
293 10.00% [.] bar
294 5.00% libc.so
295 5.00% [.] libcall
296
297--overwrite::
298 Enable this to use just the most recent records, which helps in high core count
299 machines such as Knights Landing/Mill, but right now is disabled by default as
300 the pausing used in this technique is leading to loss of metadata events such
301 as PERF_RECORD_MMAP which makes 'perf top' unable to resolve samples, leading
302 to lots of unknown samples appearing on the UI. Enable this if you are in such
303 machines and profiling a workload that doesn't creates short lived threads and/or
304 doesn't uses many executable mmap operations. Work is being planed to solve
305 this situation, till then, this will remain disabled by default.
306
307--force::
308 Don't do ownership validation.
309
310--num-thread-synthesize::
311 The number of threads to run when synthesizing events for existing processes.
312 By default, the number of threads equals to the number of online CPUs.
313
314--namespaces::
315 Record events of type PERF_RECORD_NAMESPACES and display it with the
316 'cgroup_id' sort key.
317
318-G name::
319--cgroup name::
320monitor only in the container (cgroup) called "name". This option is available only
321in per-cpu mode. The cgroup filesystem must be mounted. All threads belonging to
322container "name" are monitored when they run on the monitored CPUs. Multiple cgroups
323can be provided. Each cgroup is applied to the corresponding event, i.e., first cgroup
324to first event, second cgroup to second event and so on. It is possible to provide
325an empty cgroup (monitor all the time) using, e.g., -G foo,,bar. Cgroups must have
326corresponding events, i.e., they always refer to events defined earlier on the command
327line. If the user wants to track multiple events for a specific cgroup, the user can
328use '-e e1 -e e2 -G foo,foo' or just use '-e e1 -e e2 -G foo'.
329
330--all-cgroups::
331 Record events of type PERF_RECORD_CGROUP and display it with the
332 'cgroup' sort key.
333
334--switch-on EVENT_NAME::
335 Only consider events after this event is found.
336
337 E.g.:
338
339 Find out where broadcast packets are handled
340
341 perf probe -L icmp_rcv
342
343 Insert a probe there:
344
345 perf probe icmp_rcv:59
346
347 Start perf top and ask it to only consider the cycles events when a
348 broadcast packet arrives This will show a menu with two entries and
349 will start counting when a broadcast packet arrives:
350
351 perf top -e cycles,probe:icmp_rcv --switch-on=probe:icmp_rcv
352
353 Alternatively one can ask for a group and then two overhead columns
354 will appear, the first for cycles and the second for the switch-on event.
355
356 perf top -e '{cycles,probe:icmp_rcv}' --switch-on=probe:icmp_rcv
357
358 This may be interesting to measure a workload only after some initialization
359 phase is over, i.e. insert a perf probe at that point and use the above
360 examples replacing probe:icmp_rcv with the just-after-init probe.
361
362--switch-off EVENT_NAME::
363 Stop considering events after this event is found.
364
365--show-on-off-events::
366 Show the --switch-on/off events too. This has no effect in 'perf top' now
367 but probably we'll make the default not to show the switch-on/off events
368 on the --group mode and if there is only one event besides the off/on ones,
369 go straight to the histogram browser, just like 'perf top' with no events
370 explicitly specified does.
371
372--stitch-lbr::
373 Show callgraph with stitched LBRs, which may have more complete
374 callgraph. The option must be used with --call-graph lbr recording.
375 Disabled by default. In common cases with call stack overflows,
376 it can recreate better call stacks than the default lbr call stack
377 output. But this approach is not foolproof. There can be cases
378 where it creates incorrect call stacks from incorrect matches.
379 The known limitations include exception handing such as
380 setjmp/longjmp will have calls/returns not match.
381
382ifdef::HAVE_LIBPFM[]
383--pfm-events events::
384Select a PMU event using libpfm4 syntax (see http://perfmon2.sf.net)
385including support for event filters. For example '--pfm-events
386inst_retired:any_p:u:c=1:i'. More than one event can be passed to the
387option using the comma separator. Hardware events and generic hardware
388events cannot be mixed together. The latter must be used with the -e
389option. The -e option and this one can be mixed and matched. Events
390can be grouped using the {} notation.
391endif::HAVE_LIBPFM[]
392
393INTERACTIVE PROMPTING KEYS
394--------------------------
395
396[d]::
397 Display refresh delay.
398
399[e]::
400 Number of entries to display.
401
402[E]::
403 Event to display when multiple counters are active.
404
405[f]::
406 Profile display filter (>= hit count).
407
408[F]::
409 Annotation display filter (>= % of total).
410
411[s]::
412 Annotate symbol.
413
414[S]::
415 Stop annotation, return to full profile display.
416
417[K]::
418 Hide kernel symbols.
419
420[U]::
421 Hide user symbols.
422
423[z]::
424 Toggle event count zeroing across display updates.
425
426[qQ]::
427 Quit.
428
429Pressing any unmapped key displays a menu, and prompts for input.
430
431include::callchain-overhead-calculation.txt[]
432
433SEE ALSO
434--------
435linkperf:perf-stat[1], linkperf:perf-list[1], linkperf:perf-report[1]