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-F <freq>::
57--freq=<freq>::
58	Profile at this frequency. Use 'max' to use the currently maximum
59	allowed frequency, i.e. the value in the kernel.perf_event_max_sample_rate
60	sysctl.
61
62-i::
63--inherit::
64	Child tasks do not inherit counters.
65
66-k <path>::
67--vmlinux=<path>::
68	Path to vmlinux.  Required for annotation functionality.
69
70--ignore-vmlinux::
71	Ignore vmlinux files.
72
73--kallsyms=<file>::
74	kallsyms pathname
75
76-m <pages>::
77--mmap-pages=<pages>::
78	Number of mmap data pages (must be a power of two) or size
79	specification with appended unit character - B/K/M/G. The
80	size is rounded up to have nearest pages power of two value.
81
82-p <pid>::
83--pid=<pid>::
84	Profile events on existing Process ID (comma separated list).
85
86-t <tid>::
87--tid=<tid>::
88        Profile events on existing thread ID (comma separated list).
89
90-u::
91--uid=::
92        Record events in threads owned by uid. Name or number.
93
94-r <priority>::
95--realtime=<priority>::
96	Collect data with this RT SCHED_FIFO priority.
97
98--sym-annotate=<symbol>::
99        Annotate this symbol.
100
101-K::
102--hide_kernel_symbols::
103        Hide kernel symbols.
104
105-U::
106--hide_user_symbols::
107        Hide user symbols.
108
109--demangle-kernel::
110        Demangle kernel symbols.
111
112-D::
113--dump-symtab::
114        Dump the symbol table used for profiling.
115
116-v::
117--verbose::
118	Be more verbose (show counter open errors, etc).
119
120-z::
121--zero::
122	Zero history across display updates.
123
124-s::
125--sort::
126	Sort by key(s): pid, comm, dso, symbol, parent, srcline, weight,
127	local_weight, abort, in_tx, transaction, overhead, sample, period.
128	Please see description of --sort in the perf-report man page.
129
130--fields=::
131	Specify output field - multiple keys can be specified in CSV format.
132	Following fields are available:
133	overhead, overhead_sys, overhead_us, overhead_children, sample and period.
134	Also it can contain any sort key(s).
135
136	By default, every sort keys not specified in --field will be appended
137	automatically.
138
139-n::
140--show-nr-samples::
141	Show a column with the number of samples.
142
143--show-total-period::
144	Show a column with the sum of periods.
145
146--dsos::
147	Only consider symbols in these dsos.  This option will affect the
148	percentage of the overhead column.  See --percentage for more info.
149
150--comms::
151	Only consider symbols in these comms.  This option will affect the
152	percentage of the overhead column.  See --percentage for more info.
153
154--symbols::
155	Only consider these symbols.  This option will affect the
156	percentage of the overhead column.  See --percentage for more info.
157
158-M::
159--disassembler-style=:: Set disassembler style for objdump.
160
161--source::
162	Interleave source code with assembly code. Enabled by default,
163	disable with --no-source.
164
165--asm-raw::
166	Show raw instruction encoding of assembly instructions.
167
168-g::
169	Enables call-graph (stack chain/backtrace) recording.
170
171--call-graph [mode,type,min[,limit],order[,key][,branch]]::
172	Setup and enable call-graph (stack chain/backtrace) recording,
173	implies -g.  See `--call-graph` section in perf-record and
174	perf-report man pages for details.
175
176--children::
177	Accumulate callchain of children to parent entry so that then can
178	show up in the output.  The output will have a new "Children" column
179	and will be sorted on the data.  It requires -g/--call-graph option
180	enabled.  See the `overhead calculation' section for more details.
181	Enabled by default, disable with --no-children.
182
183--max-stack::
184	Set the stack depth limit when parsing the callchain, anything
185	beyond the specified depth will be ignored. This is a trade-off
186	between information loss and faster processing especially for
187	workloads that can have a very long callchain stack.
188
189	Default: /proc/sys/kernel/perf_event_max_stack when present, 127 otherwise.
190
191--ignore-callees=<regex>::
192        Ignore callees of the function(s) matching the given regex.
193        This has the effect of collecting the callers of each such
194        function into one place in the call-graph tree.
195
196--percent-limit::
197	Do not show entries which have an overhead under that percent.
198	(Default: 0).
199
200--percentage::
201	Determine how to display the overhead percentage of filtered entries.
202	Filters can be applied by --comms, --dsos and/or --symbols options and
203	Zoom operations on the TUI (thread, dso, etc).
204
205	"relative" means it's relative to filtered entries only so that the
206	sum of shown entries will be always 100%. "absolute" means it retains
207	the original value before and after the filter is applied.
208
209-w::
210--column-widths=<width[,width...]>::
211	Force each column width to the provided list, for large terminal
212	readability.  0 means no limit (default behavior).
213
214--proc-map-timeout::
215	When processing pre-existing threads /proc/XXX/mmap, it may take
216	a long time, because the file may be huge. A time out is needed
217	in such cases.
218	This option sets the time out limit. The default value is 500 ms.
219
220
221-b::
222--branch-any::
223	Enable taken branch stack sampling. Any type of taken branch may be sampled.
224	This is a shortcut for --branch-filter any. See --branch-filter for more infos.
225
226-j::
227--branch-filter::
228	Enable taken branch stack sampling. Each sample captures a series of consecutive
229	taken branches. The number of branches captured with each sample depends on the
230	underlying hardware, the type of branches of interest, and the executed code.
231	It is possible to select the types of branches captured by enabling filters.
232	For a full list of modifiers please see the perf record manpage.
233
234	The option requires at least one branch type among any, any_call, any_ret, ind_call, cond.
235	The privilege levels may be omitted, in which case, the privilege levels of the associated
236	event are applied to the branch filter. Both kernel (k) and hypervisor (hv) privilege
237	levels are subject to permissions.  When sampling on multiple events, branch stack sampling
238	is enabled for all the sampling events. The sampled branch type is the same for all events.
239	The various filters must be specified as a comma separated list: --branch-filter any_ret,u,k
240	Note that this feature may not be available on all processors.
241
242--raw-trace::
243	When displaying traceevent output, do not use print fmt or plugins.
244
245--hierarchy::
246	Enable hierarchy output.
247
248--overwrite::
249	Enable this to use just the most recent records, which helps in high core count
250	machines such as Knights Landing/Mill, but right now is disabled by default as
251	the pausing used in this technique is leading to loss of metadata events such
252	as PERF_RECORD_MMAP which makes 'perf top' unable to resolve samples, leading
253	to lots of unknown samples appearing on the UI. Enable this if you are in such
254	machines and profiling a workload that doesn't creates short lived threads and/or
255	doesn't uses many executable mmap operations. Work is being planed to solve
256	this situation, till then, this will remain disabled by default.
257
258--force::
259	Don't do ownership validation.
260
261--num-thread-synthesize::
262	The number of threads to run when synthesizing events for existing processes.
263	By default, the number of threads equals to the number of online CPUs.
264
265INTERACTIVE PROMPTING KEYS
266--------------------------
267
268[d]::
269	Display refresh delay.
270
271[e]::
272	Number of entries to display.
273
274[E]::
275	Event to display when multiple counters are active.
276
277[f]::
278	Profile display filter (>= hit count).
279
280[F]::
281	Annotation display filter (>= % of total).
282
283[s]::
284	Annotate symbol.
285
286[S]::
287	Stop annotation, return to full profile display.
288
289[K]::
290	Hide kernel symbols.
291
292[U]::
293	Hide user symbols.
294
295[z]::
296	Toggle event count zeroing across display updates.
297
298[qQ]::
299	Quit.
300
301Pressing any unmapped key displays a menu, and prompts for input.
302
303include::callchain-overhead-calculation.txt[]
304
305SEE ALSO
306--------
307linkperf:perf-stat[1], linkperf:perf-list[1], linkperf:perf-report[1]
308