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--prefix=PREFIX:: 162--prefix-strip=N:: 163 Remove first N entries from source file path names in executables 164 and add PREFIX. This allows to display source code compiled on systems 165 with different file system layout. 166 167--source:: 168 Interleave source code with assembly code. Enabled by default, 169 disable with --no-source. 170 171--asm-raw:: 172 Show raw instruction encoding of assembly instructions. 173 174-g:: 175 Enables call-graph (stack chain/backtrace) recording. 176 177--call-graph [mode,type,min[,limit],order[,key][,branch]]:: 178 Setup and enable call-graph (stack chain/backtrace) recording, 179 implies -g. See `--call-graph` section in perf-record and 180 perf-report man pages for details. 181 182--children:: 183 Accumulate callchain of children to parent entry so that then can 184 show up in the output. The output will have a new "Children" column 185 and will be sorted on the data. It requires -g/--call-graph option 186 enabled. See the `overhead calculation' section for more details. 187 Enabled by default, disable with --no-children. 188 189--max-stack:: 190 Set the stack depth limit when parsing the callchain, anything 191 beyond the specified depth will be ignored. This is a trade-off 192 between information loss and faster processing especially for 193 workloads that can have a very long callchain stack. 194 195 Default: /proc/sys/kernel/perf_event_max_stack when present, 127 otherwise. 196 197--ignore-callees=<regex>:: 198 Ignore callees of the function(s) matching the given regex. 199 This has the effect of collecting the callers of each such 200 function into one place in the call-graph tree. 201 202--percent-limit:: 203 Do not show entries which have an overhead under that percent. 204 (Default: 0). 205 206--percentage:: 207 Determine how to display the overhead percentage of filtered entries. 208 Filters can be applied by --comms, --dsos and/or --symbols options and 209 Zoom operations on the TUI (thread, dso, etc). 210 211 "relative" means it's relative to filtered entries only so that the 212 sum of shown entries will be always 100%. "absolute" means it retains 213 the original value before and after the filter is applied. 214 215-w:: 216--column-widths=<width[,width...]>:: 217 Force each column width to the provided list, for large terminal 218 readability. 0 means no limit (default behavior). 219 220--proc-map-timeout:: 221 When processing pre-existing threads /proc/XXX/mmap, it may take 222 a long time, because the file may be huge. A time out is needed 223 in such cases. 224 This option sets the time out limit. The default value is 500 ms. 225 226 227-b:: 228--branch-any:: 229 Enable taken branch stack sampling. Any type of taken branch may be sampled. 230 This is a shortcut for --branch-filter any. See --branch-filter for more infos. 231 232-j:: 233--branch-filter:: 234 Enable taken branch stack sampling. Each sample captures a series of consecutive 235 taken branches. The number of branches captured with each sample depends on the 236 underlying hardware, the type of branches of interest, and the executed code. 237 It is possible to select the types of branches captured by enabling filters. 238 For a full list of modifiers please see the perf record manpage. 239 240 The option requires at least one branch type among any, any_call, any_ret, ind_call, cond. 241 The privilege levels may be omitted, in which case, the privilege levels of the associated 242 event are applied to the branch filter. Both kernel (k) and hypervisor (hv) privilege 243 levels are subject to permissions. When sampling on multiple events, branch stack sampling 244 is enabled for all the sampling events. The sampled branch type is the same for all events. 245 The various filters must be specified as a comma separated list: --branch-filter any_ret,u,k 246 Note that this feature may not be available on all processors. 247 248--raw-trace:: 249 When displaying traceevent output, do not use print fmt or plugins. 250 251--hierarchy:: 252 Enable hierarchy output. 253 254--overwrite:: 255 Enable this to use just the most recent records, which helps in high core count 256 machines such as Knights Landing/Mill, but right now is disabled by default as 257 the pausing used in this technique is leading to loss of metadata events such 258 as PERF_RECORD_MMAP which makes 'perf top' unable to resolve samples, leading 259 to lots of unknown samples appearing on the UI. Enable this if you are in such 260 machines and profiling a workload that doesn't creates short lived threads and/or 261 doesn't uses many executable mmap operations. Work is being planed to solve 262 this situation, till then, this will remain disabled by default. 263 264--force:: 265 Don't do ownership validation. 266 267--num-thread-synthesize:: 268 The number of threads to run when synthesizing events for existing processes. 269 By default, the number of threads equals to the number of online CPUs. 270 271--namespaces:: 272 Record events of type PERF_RECORD_NAMESPACES and display it with the 273 'cgroup_id' sort key. 274 275--switch-on EVENT_NAME:: 276 Only consider events after this event is found. 277 278 E.g.: 279 280 Find out where broadcast packets are handled 281 282 perf probe -L icmp_rcv 283 284 Insert a probe there: 285 286 perf probe icmp_rcv:59 287 288 Start perf top and ask it to only consider the cycles events when a 289 broadcast packet arrives This will show a menu with two entries and 290 will start counting when a broadcast packet arrives: 291 292 perf top -e cycles,probe:icmp_rcv --switch-on=probe:icmp_rcv 293 294 Alternatively one can ask for --group and then two overhead columns 295 will appear, the first for cycles and the second for the switch-on event. 296 297 perf top --group -e cycles,probe:icmp_rcv --switch-on=probe:icmp_rcv 298 299 This may be interesting to measure a workload only after some initialization 300 phase is over, i.e. insert a perf probe at that point and use the above 301 examples replacing probe:icmp_rcv with the just-after-init probe. 302 303--switch-off EVENT_NAME:: 304 Stop considering events after this event is found. 305 306--show-on-off-events:: 307 Show the --switch-on/off events too. This has no effect in 'perf top' now 308 but probably we'll make the default not to show the switch-on/off events 309 on the --group mode and if there is only one event besides the off/on ones, 310 go straight to the histogram browser, just like 'perf top' with no events 311 explicitely specified does. 312 313 314INTERACTIVE PROMPTING KEYS 315-------------------------- 316 317[d]:: 318 Display refresh delay. 319 320[e]:: 321 Number of entries to display. 322 323[E]:: 324 Event to display when multiple counters are active. 325 326[f]:: 327 Profile display filter (>= hit count). 328 329[F]:: 330 Annotation display filter (>= % of total). 331 332[s]:: 333 Annotate symbol. 334 335[S]:: 336 Stop annotation, return to full profile display. 337 338[K]:: 339 Hide kernel symbols. 340 341[U]:: 342 Hide user symbols. 343 344[z]:: 345 Toggle event count zeroing across display updates. 346 347[qQ]:: 348 Quit. 349 350Pressing any unmapped key displays a menu, and prompts for input. 351 352include::callchain-overhead-calculation.txt[] 353 354SEE ALSO 355-------- 356linkperf:perf-stat[1], linkperf:perf-list[1], linkperf:perf-report[1] 357