1perf-trace(1) 2============= 3 4NAME 5---- 6perf-trace - strace inspired tool 7 8SYNOPSIS 9-------- 10[verse] 11'perf trace' 12'perf trace record' 13 14DESCRIPTION 15----------- 16This command will show the events associated with the target, initially 17syscalls, but other system events like pagefaults, task lifetime events, 18scheduling events, etc. 19 20This is a live mode tool in addition to working with perf.data files like 21the other perf tools. Files can be generated using the 'perf record' command 22but the session needs to include the raw_syscalls events (-e 'raw_syscalls:*'). 23Alternatively, 'perf trace record' can be used as a shortcut to 24automatically include the raw_syscalls events when writing events to a file. 25 26The following options apply to perf trace; options to perf trace record are 27found in the perf record man page. 28 29OPTIONS 30------- 31 32-a:: 33--all-cpus:: 34 System-wide collection from all CPUs. 35 36-e:: 37--expr:: 38--event:: 39 List of syscalls and other perf events (tracepoints, HW cache events, 40 etc) to show. Globbing is supported, e.g.: "epoll_*", "*msg*", etc. 41 See 'perf list' for a complete list of events. 42 Prefixing with ! shows all syscalls but the ones specified. You may 43 need to escape it. 44 45--filter=<filter>:: 46 Event filter. This option should follow an event selector (-e) which 47 selects tracepoint event(s). 48 49 50-D msecs:: 51--delay msecs:: 52After starting the program, wait msecs before measuring. This is useful to 53filter out the startup phase of the program, which is often very different. 54 55-o:: 56--output=:: 57 Output file name. 58 59-p:: 60--pid=:: 61 Record events on existing process ID (comma separated list). 62 63-t:: 64--tid=:: 65 Record events on existing thread ID (comma separated list). 66 67-u:: 68--uid=:: 69 Record events in threads owned by uid. Name or number. 70 71-G:: 72--cgroup:: 73 Record events in threads in a cgroup. 74 75 Look for cgroups to set at the /sys/fs/cgroup/perf_event directory, then 76 remove the /sys/fs/cgroup/perf_event/ part and try: 77 78 perf trace -G A -e sched:*switch 79 80 Will set all raw_syscalls:sys_{enter,exit}, pgfault, vfs_getname, etc 81 _and_ sched:sched_switch to the 'A' cgroup, while: 82 83 perf trace -e sched:*switch -G A 84 85 will only set the sched:sched_switch event to the 'A' cgroup, all the 86 other events (raw_syscalls:sys_{enter,exit}, etc are left "without" 87 a cgroup (on the root cgroup, sys wide, etc). 88 89 Multiple cgroups: 90 91 perf trace -G A -e sched:*switch -G B 92 93 the syscall ones go to the 'A' cgroup, the sched:sched_switch goes 94 to the 'B' cgroup. 95 96--filter-pids=:: 97 Filter out events for these pids and for 'trace' itself (comma separated list). 98 99-v:: 100--verbose:: 101 Increase the verbosity level. 102 103--no-inherit:: 104 Child tasks do not inherit counters. 105 106-m:: 107--mmap-pages=:: 108 Number of mmap data pages (must be a power of two) or size 109 specification in bytes with appended unit character - B/K/M/G. 110 The size is rounded up to the nearest power-of-two page value. 111 112-C:: 113--cpu:: 114Collect samples only on the list of CPUs provided. Multiple CPUs can be provided as a 115comma-separated list with no space: 0,1. Ranges of CPUs are specified with -: 0-2. 116In per-thread mode with inheritance mode on (default), Events are captured only when 117the thread executes on the designated CPUs. Default is to monitor all CPUs. 118 119--duration:: 120 Show only events that had a duration greater than N.M ms. 121 122--sched:: 123 Accrue thread runtime and provide a summary at the end of the session. 124 125--failure:: 126 Show only syscalls that failed, i.e. that returned < 0. 127 128-i:: 129--input:: 130 Process events from a given perf data file. 131 132-T:: 133--time:: 134 Print full timestamp rather time relative to first sample. 135 136--comm:: 137 Show process COMM right beside its ID, on by default, disable with --no-comm. 138 139-s:: 140--summary:: 141 Show only a summary of syscalls by thread with min, max, and average times 142 (in msec) and relative stddev. 143 144-S:: 145--with-summary:: 146 Show all syscalls followed by a summary by thread with min, max, and 147 average times (in msec) and relative stddev. 148 149--errno-summary:: 150 To be used with -s or -S, to show stats for the errnos experienced by 151 syscalls, using only this option will trigger --summary. 152 153--summary-mode=mode:: 154 To be used with -s or -S, to select how to show summary. By default it'll 155 show the syscall summary by thread. Possible values are: thread, total, 156 cgroup. 157 158--tool_stats:: 159 Show tool stats such as number of times fd->pathname was discovered thru 160 hooking the open syscall return + vfs_getname or via reading /proc/pid/fd, etc. 161 162-f:: 163--force:: 164 Don't complain, do it. 165 166-F=[all|min|maj]:: 167--pf=[all|min|maj]:: 168 Trace pagefaults. Optionally, you can specify whether you want minor, 169 major or all pagefaults. Default value is maj. 170 171--syscalls:: 172 Trace system calls. This options is enabled by default, disable with 173 --no-syscalls. 174 175--call-graph [mode,type,min[,limit],order[,key][,branch]]:: 176 Setup and enable call-graph (stack chain/backtrace) recording. 177 See `--call-graph` section in perf-record and perf-report 178 man pages for details. The ones that are most useful in 'perf trace' 179 are 'dwarf' and 'lbr', where available, try: 'perf trace --call-graph dwarf'. 180 181 Using this will, for the root user, bump the value of --mmap-pages to 4 182 times the maximum for non-root users, based on the kernel.perf_event_mlock_kb 183 sysctl. This is done only if the user doesn't specify a --mmap-pages value. 184 185--kernel-syscall-graph:: 186 Show the kernel callchains on the syscall exit path. 187 188--max-events=N:: 189 Stop after processing N events. Note that strace-like events are considered 190 only at exit time or when a syscall is interrupted, i.e. in those cases this 191 option is equivalent to the number of lines printed. 192 193--switch-on EVENT_NAME:: 194 Only consider events after this event is found. 195 196--switch-off EVENT_NAME:: 197 Stop considering events after this event is found. 198 199--show-on-off-events:: 200 Show the --switch-on/off events too. 201 202--show-cpu:: 203 Show cpu id. 204 205--max-stack:: 206 Set the stack depth limit when parsing the callchain, anything 207 beyond the specified depth will be ignored. Note that at this point 208 this is just about the presentation part, i.e. the kernel is still 209 not limiting, the overhead of callchains needs to be set via the 210 knobs in --call-graph dwarf. 211 212 Implies '--call-graph dwarf' when --call-graph not present on the 213 command line, on systems where DWARF unwinding was built in. 214 215 Default: /proc/sys/kernel/perf_event_max_stack when present for 216 live sessions (without --input/-i), 127 otherwise. 217 218--min-stack:: 219 Set the stack depth limit when parsing the callchain, anything 220 below the specified depth will be ignored. Disabled by default. 221 222 Implies '--call-graph dwarf' when --call-graph not present on the 223 command line, on systems where DWARF unwinding was built in. 224 225--print-sample:: 226 Print the PERF_RECORD_SAMPLE PERF_SAMPLE_ info for the 227 raw_syscalls:sys_{enter,exit} tracepoints, for debugging. 228 229--proc-map-timeout:: 230 When processing pre-existing threads /proc/XXX/mmap, it may take a long time, 231 because the file may be huge. A time out is needed in such cases. 232 This option sets the time out limit. The default value is 500 ms. 233 234--sort-events:: 235 Do sorting on batches of events, use when noticing out of order events that 236 may happen, for instance, when a thread gets migrated to a different CPU 237 while processing a syscall. 238 239--libtraceevent_print:: 240 Use libtraceevent to print tracepoint arguments. By default 'perf trace' uses 241 the same beautifiers used in the strace-like enter+exit lines to augment the 242 tracepoint arguments. 243 244--force-btf:: 245 Use btf_dump to pretty print syscall argument data, instead of using hand-crafted pretty 246 printers. This option is intended for testing BTF integration in perf trace. btf_dump-based 247 pretty-printing serves as a fallback to hand-crafted pretty printers, as the latter can 248 better pretty-print integer flags and struct pointers. 249 250--bpf-summary:: 251 Collect system call statistics in BPF. This is only for live mode and 252 works well with -s/--summary option where no argument information is 253 required. 254 255--max-summary=N:: 256 Maximum number of lines in the summary mode. Note that this applies to 257 each entry (thread or cgroup). 258 259 260PAGEFAULTS 261---------- 262 263When tracing pagefaults, the format of the trace is as follows: 264 265<min|maj>fault [<ip.symbol>+<ip.offset>] => <addr.dso@addr.offset> (<map type><addr level>). 266 267- min/maj indicates whether fault event is minor or major; 268- ip.symbol shows symbol for instruction pointer (the code that generated the 269 fault); if no debug symbols available, perf trace will print raw IP; 270- addr.dso shows DSO for the faulted address; 271- map type is either 'd' for non-executable maps or 'x' for executable maps; 272- addr level is either 'k' for kernel dso or '.' for user dso. 273 274For symbols resolution you may need to install debugging symbols. 275 276Please be aware that duration is currently always 0 and doesn't reflect actual 277time it took for fault to be handled! 278 279When --verbose specified, perf trace tries to print all available information 280for both IP and fault address in the form of dso@symbol+offset. 281 282EXAMPLES 283-------- 284 285Trace only major pagefaults: 286 287 $ perf trace --no-syscalls -F 288 289Trace syscalls, major and minor pagefaults: 290 291 $ perf trace -F all 292 293 1416.547 ( 0.000 ms): python/20235 majfault [CRYPTO_push_info_+0x0] => /lib/x86_64-linux-gnu/libcrypto.so.1.0.0@0x61be0 (x.) 294 295 As you can see, there was major pagefault in python process, from 296 CRYPTO_push_info_ routine which faulted somewhere in libcrypto.so. 297 298Trace the first 4 open, openat or open_by_handle_at syscalls (in the future more syscalls may match here): 299 300 $ perf trace -e open* --max-events 4 301 [root@jouet perf]# trace -e open* --max-events 4 302 2272.992 ( 0.037 ms): gnome-shell/1370 openat(dfd: CWD, filename: /proc/self/stat) = 31 303 2277.481 ( 0.139 ms): gnome-shell/3039 openat(dfd: CWD, filename: /proc/self/stat) = 65 304 3026.398 ( 0.076 ms): gnome-shell/3039 openat(dfd: CWD, filename: /proc/self/stat) = 65 305 4294.665 ( 0.015 ms): sed/15879 openat(dfd: CWD, filename: /etc/ld.so.cache, flags: CLOEXEC) = 3 306 $ 307 308Trace the first minor page fault when running a workload: 309 310 # perf trace -F min --max-stack=7 --max-events 1 sleep 1 311 0.000 ( 0.000 ms): sleep/18006 minfault [__clear_user+0x1a] => 0x5626efa56080 (?k) 312 __clear_user ([kernel.kallsyms]) 313 load_elf_binary ([kernel.kallsyms]) 314 search_binary_handler ([kernel.kallsyms]) 315 __do_execve_file.isra.33 ([kernel.kallsyms]) 316 __x64_sys_execve ([kernel.kallsyms]) 317 do_syscall_64 ([kernel.kallsyms]) 318 entry_SYSCALL_64 ([kernel.kallsyms]) 319 # 320 321Trace the next min page page fault to take place on the first CPU: 322 323 # perf trace -F min --call-graph=dwarf --max-events 1 --cpu 0 324 0.000 ( 0.000 ms): Web Content/17136 minfault [js::gc::Chunk::fetchNextDecommittedArena+0x4b] => 0x7fbe6181b000 (?.) 325 js::gc::FreeSpan::initAsEmpty (inlined) 326 js::gc::Arena::setAsNotAllocated (inlined) 327 js::gc::Chunk::fetchNextDecommittedArena (/usr/lib64/firefox/libxul.so) 328 js::gc::Chunk::allocateArena (/usr/lib64/firefox/libxul.so) 329 js::gc::GCRuntime::allocateArena (/usr/lib64/firefox/libxul.so) 330 js::gc::ArenaLists::allocateFromArena (/usr/lib64/firefox/libxul.so) 331 js::gc::GCRuntime::tryNewTenuredThing<JSString, (js::AllowGC)1> (inlined) 332 js::AllocateString<JSString, (js::AllowGC)1> (/usr/lib64/firefox/libxul.so) 333 js::Allocate<JSThinInlineString, (js::AllowGC)1> (inlined) 334 JSThinInlineString::new_<(js::AllowGC)1> (inlined) 335 AllocateInlineString<(js::AllowGC)1, unsigned char> (inlined) 336 js::ConcatStrings<(js::AllowGC)1> (/usr/lib64/firefox/libxul.so) 337 [0x18b26e6bc2bd] (/tmp/perf-17136.map) 338 # 339 340Trace the next two sched:sched_switch events, four block:*_plug events, the 341next block:*_unplug and the next three net:*dev_queue events, this last one 342with a backtrace of at most 16 entries, system wide: 343 344 # perf trace -e sched:*switch/nr=2/,block:*_plug/nr=4/,block:*_unplug/nr=1/,net:*dev_queue/nr=3,max-stack=16/ 345 0.000 :0/0 sched:sched_switch:swapper/2:0 [120] S ==> rcu_sched:10 [120] 346 0.015 rcu_sched/10 sched:sched_switch:rcu_sched:10 [120] R ==> swapper/2:0 [120] 347 254.198 irq/50-iwlwifi/680 net:net_dev_queue:dev=wlp3s0 skbaddr=0xffff93498051f600 len=66 348 __dev_queue_xmit ([kernel.kallsyms]) 349 273.977 :0/0 net:net_dev_queue:dev=wlp3s0 skbaddr=0xffff93498051f600 len=78 350 __dev_queue_xmit ([kernel.kallsyms]) 351 274.007 :0/0 net:net_dev_queue:dev=wlp3s0 skbaddr=0xffff93498051ff00 len=78 352 __dev_queue_xmit ([kernel.kallsyms]) 353 2930.140 kworker/u16:58/2722 block:block_plug:[kworker/u16:58] 354 2930.162 kworker/u16:58/2722 block:block_unplug:[kworker/u16:58] 1 355 4466.094 jbd2/dm-2-8/748 block:block_plug:[jbd2/dm-2-8] 356 8050.123 kworker/u16:30/2694 block:block_plug:[kworker/u16:30] 357 8050.271 kworker/u16:30/2694 block:block_plug:[kworker/u16:30] 358 # 359 360SEE ALSO 361-------- 362linkperf:perf-record[1], linkperf:perf-script[1] 363