perf-record.txt (29982B)
1perf-record(1) 2============== 3 4NAME 5---- 6perf-record - Run a command and record its profile into perf.data 7 8SYNOPSIS 9-------- 10[verse] 11'perf record' [-e <EVENT> | --event=EVENT] [-a] <command> 12'perf record' [-e <EVENT> | --event=EVENT] [-a] \-- <command> [<options>] 13 14DESCRIPTION 15----------- 16This command runs a command and gathers a performance counter profile 17from it, into perf.data - without displaying anything. 18 19This file can then be inspected later on, using 'perf report'. 20 21 22OPTIONS 23------- 24<command>...:: 25 Any command you can specify in a shell. 26 27-e:: 28--event=:: 29 Select the PMU event. Selection can be: 30 31 - a symbolic event name (use 'perf list' to list all events) 32 33 - a raw PMU event in the form of rN where N is a hexadecimal value 34 that represents the raw register encoding with the layout of the 35 event control registers as described by entries in 36 /sys/bus/event_source/devices/cpu/format/*. 37 38 - a symbolic or raw PMU event followed by an optional colon 39 and a list of event modifiers, e.g., cpu-cycles:p. See the 40 linkperf:perf-list[1] man page for details on event modifiers. 41 42 - a symbolically formed PMU event like 'pmu/param1=0x3,param2/' where 43 'param1', 'param2', etc are defined as formats for the PMU in 44 /sys/bus/event_source/devices/<pmu>/format/*. 45 46 - a symbolically formed event like 'pmu/config=M,config1=N,config3=K/' 47 48 where M, N, K are numbers (in decimal, hex, octal format). Acceptable 49 values for each of 'config', 'config1' and 'config2' are defined by 50 corresponding entries in /sys/bus/event_source/devices/<pmu>/format/* 51 param1 and param2 are defined as formats for the PMU in: 52 /sys/bus/event_source/devices/<pmu>/format/* 53 54 There are also some parameters which are not defined in .../<pmu>/format/*. 55 These params can be used to overload default config values per event. 56 Here are some common parameters: 57 - 'period': Set event sampling period 58 - 'freq': Set event sampling frequency 59 - 'time': Disable/enable time stamping. Acceptable values are 1 for 60 enabling time stamping. 0 for disabling time stamping. 61 The default is 1. 62 - 'call-graph': Disable/enable callgraph. Acceptable str are "fp" for 63 FP mode, "dwarf" for DWARF mode, "lbr" for LBR mode and 64 "no" for disable callgraph. 65 - 'stack-size': user stack size for dwarf mode 66 - 'name' : User defined event name. Single quotes (') may be used to 67 escape symbols in the name from parsing by shell and tool 68 like this: name=\'CPU_CLK_UNHALTED.THREAD:cmask=0x1\'. 69 - 'aux-output': Generate AUX records instead of events. This requires 70 that an AUX area event is also provided. 71 - 'aux-sample-size': Set sample size for AUX area sampling. If the 72 '--aux-sample' option has been used, set aux-sample-size=0 to disable 73 AUX area sampling for the event. 74 75 See the linkperf:perf-list[1] man page for more parameters. 76 77 Note: If user explicitly sets options which conflict with the params, 78 the value set by the parameters will be overridden. 79 80 Also not defined in .../<pmu>/format/* are PMU driver specific 81 configuration parameters. Any configuration parameter preceded by 82 the letter '@' is not interpreted in user space and sent down directly 83 to the PMU driver. For example: 84 85 perf record -e some_event/@cfg1,@cfg2=config/ ... 86 87 will see 'cfg1' and 'cfg2=config' pushed to the PMU driver associated 88 with the event for further processing. There is no restriction on 89 what the configuration parameters are, as long as their semantic is 90 understood and supported by the PMU driver. 91 92 - a hardware breakpoint event in the form of '\mem:addr[/len][:access]' 93 where addr is the address in memory you want to break in. 94 Access is the memory access type (read, write, execute) it can 95 be passed as follows: '\mem:addr[:[r][w][x]]'. len is the range, 96 number of bytes from specified addr, which the breakpoint will cover. 97 If you want to profile read-write accesses in 0x1000, just set 98 'mem:0x1000:rw'. 99 If you want to profile write accesses in [0x1000~1008), just set 100 'mem:0x1000/8:w'. 101 102 - a BPF source file (ending in .c) or a precompiled object file (ending 103 in .o) selects one or more BPF events. 104 The BPF program can attach to various perf events based on the ELF section 105 names. 106 107 When processing a '.c' file, perf searches an installed LLVM to compile it 108 into an object file first. Optional clang options can be passed via the 109 '--clang-opt' command line option, e.g.: 110 111 perf record --clang-opt "-DLINUX_VERSION_CODE=0x50000" \ 112 -e tests/bpf-script-example.c 113 114 Note: '--clang-opt' must be placed before '--event/-e'. 115 116 - a group of events surrounded by a pair of brace ("{event1,event2,...}"). 117 Each event is separated by commas and the group should be quoted to 118 prevent the shell interpretation. You also need to use --group on 119 "perf report" to view group events together. 120 121--filter=<filter>:: 122 Event filter. This option should follow an event selector (-e) which 123 selects either tracepoint event(s) or a hardware trace PMU 124 (e.g. Intel PT or CoreSight). 125 126 - tracepoint filters 127 128 In the case of tracepoints, multiple '--filter' options are combined 129 using '&&'. 130 131 - address filters 132 133 A hardware trace PMU advertises its ability to accept a number of 134 address filters by specifying a non-zero value in 135 /sys/bus/event_source/devices/<pmu>/nr_addr_filters. 136 137 Address filters have the format: 138 139 filter|start|stop|tracestop <start> [/ <size>] [@<file name>] 140 141 Where: 142 - 'filter': defines a region that will be traced. 143 - 'start': defines an address at which tracing will begin. 144 - 'stop': defines an address at which tracing will stop. 145 - 'tracestop': defines a region in which tracing will stop. 146 147 <file name> is the name of the object file, <start> is the offset to the 148 code to trace in that file, and <size> is the size of the region to 149 trace. 'start' and 'stop' filters need not specify a <size>. 150 151 If no object file is specified then the kernel is assumed, in which case 152 the start address must be a current kernel memory address. 153 154 <start> can also be specified by providing the name of a symbol. If the 155 symbol name is not unique, it can be disambiguated by inserting #n where 156 'n' selects the n'th symbol in address order. Alternately #0, #g or #G 157 select only a global symbol. <size> can also be specified by providing 158 the name of a symbol, in which case the size is calculated to the end 159 of that symbol. For 'filter' and 'tracestop' filters, if <size> is 160 omitted and <start> is a symbol, then the size is calculated to the end 161 of that symbol. 162 163 If <size> is omitted and <start> is '*', then the start and size will 164 be calculated from the first and last symbols, i.e. to trace the whole 165 file. 166 167 If symbol names (or '*') are provided, they must be surrounded by white 168 space. 169 170 The filter passed to the kernel is not necessarily the same as entered. 171 To see the filter that is passed, use the -v option. 172 173 The kernel may not be able to configure a trace region if it is not 174 within a single mapping. MMAP events (or /proc/<pid>/maps) can be 175 examined to determine if that is a possibility. 176 177 Multiple filters can be separated with space or comma. 178 179--exclude-perf:: 180 Don't record events issued by perf itself. This option should follow 181 an event selector (-e) which selects tracepoint event(s). It adds a 182 filter expression 'common_pid != $PERFPID' to filters. If other 183 '--filter' exists, the new filter expression will be combined with 184 them by '&&'. 185 186-a:: 187--all-cpus:: 188 System-wide collection from all CPUs (default if no target is specified). 189 190-p:: 191--pid=:: 192 Record events on existing process ID (comma separated list). 193 194-t:: 195--tid=:: 196 Record events on existing thread ID (comma separated list). 197 This option also disables inheritance by default. Enable it by adding 198 --inherit. 199 200-u:: 201--uid=:: 202 Record events in threads owned by uid. Name or number. 203 204-r:: 205--realtime=:: 206 Collect data with this RT SCHED_FIFO priority. 207 208--no-buffering:: 209 Collect data without buffering. 210 211-c:: 212--count=:: 213 Event period to sample. 214 215-o:: 216--output=:: 217 Output file name. 218 219-i:: 220--no-inherit:: 221 Child tasks do not inherit counters. 222 223-F:: 224--freq=:: 225 Profile at this frequency. Use 'max' to use the currently maximum 226 allowed frequency, i.e. the value in the kernel.perf_event_max_sample_rate 227 sysctl. Will throttle down to the currently maximum allowed frequency. 228 See --strict-freq. 229 230--strict-freq:: 231 Fail if the specified frequency can't be used. 232 233-m:: 234--mmap-pages=:: 235 Number of mmap data pages (must be a power of two) or size 236 specification with appended unit character - B/K/M/G. The 237 size is rounded up to have nearest pages power of two value. 238 Also, by adding a comma, the number of mmap pages for AUX 239 area tracing can be specified. 240 241--group:: 242 Put all events in a single event group. This precedes the --event 243 option and remains only for backward compatibility. See --event. 244 245-g:: 246 Enables call-graph (stack chain/backtrace) recording for both 247 kernel space and user space. 248 249--call-graph:: 250 Setup and enable call-graph (stack chain/backtrace) recording, 251 implies -g. Default is "fp" (for user space). 252 253 The unwinding method used for kernel space is dependent on the 254 unwinder used by the active kernel configuration, i.e 255 CONFIG_UNWINDER_FRAME_POINTER (fp) or CONFIG_UNWINDER_ORC (orc) 256 257 Any option specified here controls the method used for user space. 258 259 Valid options are "fp" (frame pointer), "dwarf" (DWARF's CFI - 260 Call Frame Information) or "lbr" (Hardware Last Branch Record 261 facility). 262 263 In some systems, where binaries are build with gcc 264 --fomit-frame-pointer, using the "fp" method will produce bogus 265 call graphs, using "dwarf", if available (perf tools linked to 266 the libunwind or libdw library) should be used instead. 267 Using the "lbr" method doesn't require any compiler options. It 268 will produce call graphs from the hardware LBR registers. The 269 main limitation is that it is only available on new Intel 270 platforms, such as Haswell. It can only get user call chain. It 271 doesn't work with branch stack sampling at the same time. 272 273 When "dwarf" recording is used, perf also records (user) stack dump 274 when sampled. Default size of the stack dump is 8192 (bytes). 275 User can change the size by passing the size after comma like 276 "--call-graph dwarf,4096". 277 278-q:: 279--quiet:: 280 Don't print any message, useful for scripting. 281 282-v:: 283--verbose:: 284 Be more verbose (show counter open errors, etc). 285 286-s:: 287--stat:: 288 Record per-thread event counts. Use it with 'perf report -T' to see 289 the values. 290 291-d:: 292--data:: 293 Record the sample virtual addresses. 294 295--phys-data:: 296 Record the sample physical addresses. 297 298--data-page-size:: 299 Record the sampled data address data page size. 300 301--code-page-size:: 302 Record the sampled code address (ip) page size 303 304-T:: 305--timestamp:: 306 Record the sample timestamps. Use it with 'perf report -D' to see the 307 timestamps, for instance. 308 309-P:: 310--period:: 311 Record the sample period. 312 313--sample-cpu:: 314 Record the sample cpu. 315 316-n:: 317--no-samples:: 318 Don't sample. 319 320-R:: 321--raw-samples:: 322Collect raw sample records from all opened counters (default for tracepoint counters). 323 324-C:: 325--cpu:: 326Collect samples only on the list of CPUs provided. Multiple CPUs can be provided as a 327comma-separated list with no space: 0,1. Ranges of CPUs are specified with -: 0-2. 328In per-thread mode with inheritance mode on (default), samples are captured only when 329the thread executes on the designated CPUs. Default is to monitor all CPUs. 330 331-B:: 332--no-buildid:: 333Do not save the build ids of binaries in the perf.data files. This skips 334post processing after recording, which sometimes makes the final step in 335the recording process to take a long time, as it needs to process all 336events looking for mmap records. The downside is that it can misresolve 337symbols if the workload binaries used when recording get locally rebuilt 338or upgraded, because the only key available in this case is the 339pathname. You can also set the "record.build-id" config variable to 340'skip to have this behaviour permanently. 341 342-N:: 343--no-buildid-cache:: 344Do not update the buildid cache. This saves some overhead in situations 345where the information in the perf.data file (which includes buildids) 346is sufficient. You can also set the "record.build-id" config variable to 347'no-cache' to have the same effect. 348 349-G name,...:: 350--cgroup name,...:: 351monitor only in the container (cgroup) called "name". This option is available only 352in per-cpu mode. The cgroup filesystem must be mounted. All threads belonging to 353container "name" are monitored when they run on the monitored CPUs. Multiple cgroups 354can be provided. Each cgroup is applied to the corresponding event, i.e., first cgroup 355to first event, second cgroup to second event and so on. It is possible to provide 356an empty cgroup (monitor all the time) using, e.g., -G foo,,bar. Cgroups must have 357corresponding events, i.e., they always refer to events defined earlier on the command 358line. If the user wants to track multiple events for a specific cgroup, the user can 359use '-e e1 -e e2 -G foo,foo' or just use '-e e1 -e e2 -G foo'. 360 361If wanting to monitor, say, 'cycles' for a cgroup and also for system wide, this 362command line can be used: 'perf stat -e cycles -G cgroup_name -a -e cycles'. 363 364-b:: 365--branch-any:: 366Enable taken branch stack sampling. Any type of taken branch may be sampled. 367This is a shortcut for --branch-filter any. See --branch-filter for more infos. 368 369-j:: 370--branch-filter:: 371Enable taken branch stack sampling. Each sample captures a series of consecutive 372taken branches. The number of branches captured with each sample depends on the 373underlying hardware, the type of branches of interest, and the executed code. 374It is possible to select the types of branches captured by enabling filters. The 375following filters are defined: 376 377 - any: any type of branches 378 - any_call: any function call or system call 379 - any_ret: any function return or system call return 380 - ind_call: any indirect branch 381 - call: direct calls, including far (to/from kernel) calls 382 - u: only when the branch target is at the user level 383 - k: only when the branch target is in the kernel 384 - hv: only when the target is at the hypervisor level 385 - in_tx: only when the target is in a hardware transaction 386 - no_tx: only when the target is not in a hardware transaction 387 - abort_tx: only when the target is a hardware transaction abort 388 - cond: conditional branches 389 - save_type: save branch type during sampling in case binary is not available later 390 391+ 392The option requires at least one branch type among any, any_call, any_ret, ind_call, cond. 393The privilege levels may be omitted, in which case, the privilege levels of the associated 394event are applied to the branch filter. Both kernel (k) and hypervisor (hv) privilege 395levels are subject to permissions. When sampling on multiple events, branch stack sampling 396is enabled for all the sampling events. The sampled branch type is the same for all events. 397The various filters must be specified as a comma separated list: --branch-filter any_ret,u,k 398Note that this feature may not be available on all processors. 399 400--weight:: 401Enable weightened sampling. An additional weight is recorded per sample and can be 402displayed with the weight and local_weight sort keys. This currently works for TSX 403abort events and some memory events in precise mode on modern Intel CPUs. 404 405--namespaces:: 406Record events of type PERF_RECORD_NAMESPACES. This enables 'cgroup_id' sort key. 407 408--all-cgroups:: 409Record events of type PERF_RECORD_CGROUP. This enables 'cgroup' sort key. 410 411--transaction:: 412Record transaction flags for transaction related events. 413 414--per-thread:: 415Use per-thread mmaps. By default per-cpu mmaps are created. This option 416overrides that and uses per-thread mmaps. A side-effect of that is that 417inheritance is automatically disabled. --per-thread is ignored with a warning 418if combined with -a or -C options. 419 420-D:: 421--delay=:: 422After starting the program, wait msecs before measuring (-1: start with events 423disabled). This is useful to filter out the startup phase of the program, which 424is often very different. 425 426-I:: 427--intr-regs:: 428Capture machine state (registers) at interrupt, i.e., on counter overflows for 429each sample. List of captured registers depends on the architecture. This option 430is off by default. It is possible to select the registers to sample using their 431symbolic names, e.g. on x86, ax, si. To list the available registers use 432--intr-regs=\?. To name registers, pass a comma separated list such as 433--intr-regs=ax,bx. The list of register is architecture dependent. 434 435--user-regs:: 436Similar to -I, but capture user registers at sample time. To list the available 437user registers use --user-regs=\?. 438 439--running-time:: 440Record running and enabled time for read events (:S) 441 442-k:: 443--clockid:: 444Sets the clock id to use for the various time fields in the perf_event_type 445records. See clock_gettime(). In particular CLOCK_MONOTONIC and 446CLOCK_MONOTONIC_RAW are supported, some events might also allow 447CLOCK_BOOTTIME, CLOCK_REALTIME and CLOCK_TAI. 448 449-S:: 450--snapshot:: 451Select AUX area tracing Snapshot Mode. This option is valid only with an 452AUX area tracing event. Optionally, certain snapshot capturing parameters 453can be specified in a string that follows this option: 454 'e': take one last snapshot on exit; guarantees that there is at least one 455 snapshot in the output file; 456 <size>: if the PMU supports this, specify the desired snapshot size. 457 458In Snapshot Mode trace data is captured only when signal SIGUSR2 is received 459and on exit if the above 'e' option is given. 460 461--aux-sample[=OPTIONS]:: 462Select AUX area sampling. At least one of the events selected by the -e option 463must be an AUX area event. Samples on other events will be created containing 464data from the AUX area. Optionally sample size may be specified, otherwise it 465defaults to 4KiB. 466 467--proc-map-timeout:: 468When processing pre-existing threads /proc/XXX/mmap, it may take a long time, 469because the file may be huge. A time out is needed in such cases. 470This option sets the time out limit. The default value is 500 ms. 471 472--switch-events:: 473Record context switch events i.e. events of type PERF_RECORD_SWITCH or 474PERF_RECORD_SWITCH_CPU_WIDE. In some cases (e.g. Intel PT, CoreSight or Arm SPE) 475switch events will be enabled automatically, which can be suppressed by 476by the option --no-switch-events. 477 478--clang-path=PATH:: 479Path to clang binary to use for compiling BPF scriptlets. 480(enabled when BPF support is on) 481 482--clang-opt=OPTIONS:: 483Options passed to clang when compiling BPF scriptlets. 484(enabled when BPF support is on) 485 486--vmlinux=PATH:: 487Specify vmlinux path which has debuginfo. 488(enabled when BPF prologue is on) 489 490--buildid-all:: 491Record build-id of all DSOs regardless whether it's actually hit or not. 492 493--buildid-mmap:: 494Record build ids in mmap2 events, disables build id cache (implies --no-buildid). 495 496--aio[=n]:: 497Use <n> control blocks in asynchronous (Posix AIO) trace writing mode (default: 1, max: 4). 498Asynchronous mode is supported only when linking Perf tool with libc library 499providing implementation for Posix AIO API. 500 501--affinity=mode:: 502Set affinity mask of trace reading thread according to the policy defined by 'mode' value: 503 node - thread affinity mask is set to NUMA node cpu mask of the processed mmap buffer 504 cpu - thread affinity mask is set to cpu of the processed mmap buffer 505 506--mmap-flush=number:: 507 508Specify minimal number of bytes that is extracted from mmap data pages and 509processed for output. One can specify the number using B/K/M/G suffixes. 510 511The maximal allowed value is a quarter of the size of mmaped data pages. 512 513The default option value is 1 byte which means that every time that the output 514writing thread finds some new data in the mmaped buffer the data is extracted, 515possibly compressed (-z) and written to the output, perf.data or pipe. 516 517Larger data chunks are compressed more effectively in comparison to smaller 518chunks so extraction of larger chunks from the mmap data pages is preferable 519from the perspective of output size reduction. 520 521Also at some cases executing less output write syscalls with bigger data size 522can take less time than executing more output write syscalls with smaller data 523size thus lowering runtime profiling overhead. 524 525-z:: 526--compression-level[=n]:: 527Produce compressed trace using specified level n (default: 1 - fastest compression, 52822 - smallest trace) 529 530--all-kernel:: 531Configure all used events to run in kernel space. 532 533--all-user:: 534Configure all used events to run in user space. 535 536--kernel-callchains:: 537Collect callchains only from kernel space. I.e. this option sets 538perf_event_attr.exclude_callchain_user to 1. 539 540--user-callchains:: 541Collect callchains only from user space. I.e. this option sets 542perf_event_attr.exclude_callchain_kernel to 1. 543 544Don't use both --kernel-callchains and --user-callchains at the same time or no 545callchains will be collected. 546 547--timestamp-filename 548Append timestamp to output file name. 549 550--timestamp-boundary:: 551Record timestamp boundary (time of first/last samples). 552 553--switch-output[=mode]:: 554Generate multiple perf.data files, timestamp prefixed, switching to a new one 555based on 'mode' value: 556 "signal" - when receiving a SIGUSR2 (default value) or 557 <size> - when reaching the size threshold, size is expected to 558 be a number with appended unit character - B/K/M/G 559 <time> - when reaching the time threshold, size is expected to 560 be a number with appended unit character - s/m/h/d 561 562 Note: the precision of the size threshold hugely depends 563 on your configuration - the number and size of your ring 564 buffers (-m). It is generally more precise for higher sizes 565 (like >5M), for lower values expect different sizes. 566 567A possible use case is to, given an external event, slice the perf.data file 568that gets then processed, possibly via a perf script, to decide if that 569particular perf.data snapshot should be kept or not. 570 571Implies --timestamp-filename, --no-buildid and --no-buildid-cache. 572The reason for the latter two is to reduce the data file switching 573overhead. You can still switch them on with: 574 575 --switch-output --no-no-buildid --no-no-buildid-cache 576 577--switch-output-event:: 578Events that will cause the switch of the perf.data file, auto-selecting 579--switch-output=signal, the results are similar as internally the side band 580thread will also send a SIGUSR2 to the main one. 581 582Uses the same syntax as --event, it will just not be recorded, serving only to 583switch the perf.data file as soon as the --switch-output event is processed by 584a separate sideband thread. 585 586This sideband thread is also used to other purposes, like processing the 587PERF_RECORD_BPF_EVENT records as they happen, asking the kernel for extra BPF 588information, etc. 589 590--switch-max-files=N:: 591 592When rotating perf.data with --switch-output, only keep N files. 593 594--dry-run:: 595Parse options then exit. --dry-run can be used to detect errors in cmdline 596options. 597 598'perf record --dry-run -e' can act as a BPF script compiler if llvm.dump-obj 599in config file is set to true. 600 601--synth=TYPE:: 602Collect and synthesize given type of events (comma separated). Note that 603this option controls the synthesis from the /proc filesystem which represent 604task status for pre-existing threads. 605 606Kernel (and some other) events are recorded regardless of the 607choice in this option. For example, --synth=no would have MMAP events for 608kernel and modules. 609 610Available types are: 611 'task' - synthesize FORK and COMM events for each task 612 'mmap' - synthesize MMAP events for each process (implies 'task') 613 'cgroup' - synthesize CGROUP events for each cgroup 614 'all' - synthesize all events (default) 615 'no' - do not synthesize any of the above events 616 617--tail-synthesize:: 618Instead of collecting non-sample events (for example, fork, comm, mmap) at 619the beginning of record, collect them during finalizing an output file. 620The collected non-sample events reflects the status of the system when 621record is finished. 622 623--overwrite:: 624Makes all events use an overwritable ring buffer. An overwritable ring 625buffer works like a flight recorder: when it gets full, the kernel will 626overwrite the oldest records, that thus will never make it to the 627perf.data file. 628 629When '--overwrite' and '--switch-output' are used perf records and drops 630events until it receives a signal, meaning that something unusual was 631detected that warrants taking a snapshot of the most current events, 632those fitting in the ring buffer at that moment. 633 634'overwrite' attribute can also be set or canceled for an event using 635config terms. For example: 'cycles/overwrite/' and 'instructions/no-overwrite/'. 636 637Implies --tail-synthesize. 638 639--kcore:: 640Make a copy of /proc/kcore and place it into a directory with the perf data file. 641 642--max-size=<size>:: 643Limit the sample data max size, <size> is expected to be a number with 644appended unit character - B/K/M/G 645 646--num-thread-synthesize:: 647 The number of threads to run when synthesizing events for existing processes. 648 By default, the number of threads equals 1. 649 650ifdef::HAVE_LIBPFM[] 651--pfm-events events:: 652Select a PMU event using libpfm4 syntax (see http://perfmon2.sf.net) 653including support for event filters. For example '--pfm-events 654inst_retired:any_p:u:c=1:i'. More than one event can be passed to the 655option using the comma separator. Hardware events and generic hardware 656events cannot be mixed together. The latter must be used with the -e 657option. The -e option and this one can be mixed and matched. Events 658can be grouped using the {} notation. 659endif::HAVE_LIBPFM[] 660 661--control=fifo:ctl-fifo[,ack-fifo]:: 662--control=fd:ctl-fd[,ack-fd]:: 663ctl-fifo / ack-fifo are opened and used as ctl-fd / ack-fd as follows. 664Listen on ctl-fd descriptor for command to control measurement. 665 666Available commands: 667 'enable' : enable events 668 'disable' : disable events 669 'enable name' : enable event 'name' 670 'disable name' : disable event 'name' 671 'snapshot' : AUX area tracing snapshot). 672 'stop' : stop perf record 673 'ping' : ping 674 675 'evlist [-v|-g|-F] : display all events 676 -F Show just the sample frequency used for each event. 677 -v Show all fields. 678 -g Show event group information. 679 680Measurements can be started with events disabled using --delay=-1 option. Optionally 681send control command completion ('ack\n') to ack-fd descriptor to synchronize with the 682controlling process. Example of bash shell script to enable and disable events during 683measurements: 684 685 #!/bin/bash 686 687 ctl_dir=/tmp/ 688 689 ctl_fifo=${ctl_dir}perf_ctl.fifo 690 test -p ${ctl_fifo} && unlink ${ctl_fifo} 691 mkfifo ${ctl_fifo} 692 exec {ctl_fd}<>${ctl_fifo} 693 694 ctl_ack_fifo=${ctl_dir}perf_ctl_ack.fifo 695 test -p ${ctl_ack_fifo} && unlink ${ctl_ack_fifo} 696 mkfifo ${ctl_ack_fifo} 697 exec {ctl_fd_ack}<>${ctl_ack_fifo} 698 699 perf record -D -1 -e cpu-cycles -a \ 700 --control fd:${ctl_fd},${ctl_fd_ack} \ 701 -- sleep 30 & 702 perf_pid=$! 703 704 sleep 5 && echo 'enable' >&${ctl_fd} && read -u ${ctl_fd_ack} e1 && echo "enabled(${e1})" 705 sleep 10 && echo 'disable' >&${ctl_fd} && read -u ${ctl_fd_ack} d1 && echo "disabled(${d1})" 706 707 exec {ctl_fd_ack}>&- 708 unlink ${ctl_ack_fifo} 709 710 exec {ctl_fd}>&- 711 unlink ${ctl_fifo} 712 713 wait -n ${perf_pid} 714 exit $? 715 716--threads=<spec>:: 717Write collected trace data into several data files using parallel threads. 718<spec> value can be user defined list of masks. Masks separated by colon 719define CPUs to be monitored by a thread and affinity mask of that thread 720is separated by slash: 721 722 <cpus mask 1>/<affinity mask 1>:<cpus mask 2>/<affinity mask 2>:... 723 724CPUs or affinity masks must not overlap with other corresponding masks. 725Invalid CPUs are ignored, but masks containing only invalid CPUs are not 726allowed. 727 728For example user specification like the following: 729 730 0,2-4/2-4:1,5-7/5-7 731 732specifies parallel threads layout that consists of two threads, 733the first thread monitors CPUs 0 and 2-4 with the affinity mask 2-4, 734the second monitors CPUs 1 and 5-7 with the affinity mask 5-7. 735 736<spec> value can also be a string meaning predefined parallel threads 737layout: 738 739 cpu - create new data streaming thread for every monitored cpu 740 core - create new thread to monitor CPUs grouped by a core 741 package - create new thread to monitor CPUs grouped by a package 742 numa - create new threed to monitor CPUs grouped by a NUMA domain 743 744Predefined layouts can be used on systems with large number of CPUs in 745order not to spawn multiple per-cpu streaming threads but still avoid LOST 746events in data directory files. Option specified with no or empty value 747defaults to CPU layout. Masks defined or provided by the option value are 748filtered through the mask provided by -C option. 749 750include::intel-hybrid.txt[] 751 752--debuginfod[=URLs]:: 753 Specify debuginfod URL to be used when cacheing perf.data binaries, 754 it follows the same syntax as the DEBUGINFOD_URLS variable, like: 755 756 http://192.168.122.174:8002 757 758 If the URLs is not specified, the value of DEBUGINFOD_URLS 759 system environment variable is used. 760 761--off-cpu:: 762 Enable off-cpu profiling with BPF. The BPF program will collect 763 task scheduling information with (user) stacktrace and save them 764 as sample data of a software event named "offcpu-time". The 765 sample period will have the time the task slept in nanoseconds. 766 767 Note that BPF can collect stack traces using frame pointer ("fp") 768 only, as of now. So the applications built without the frame 769 pointer might see bogus addresses. 770 771SEE ALSO 772-------- 773linkperf:perf-stat[1], linkperf:perf-list[1], linkperf:perf-intel-pt[1]