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