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--tool_stats:: 154 Show tool stats such as number of times fd->pathname was discovered thru 155 hooking the open syscall return + vfs_getname or via reading /proc/pid/fd, etc. 156 157-f:: 158--force:: 159 Don't complain, do it. 160 161-F=[all|min|maj]:: 162--pf=[all|min|maj]:: 163 Trace pagefaults. Optionally, you can specify whether you want minor, 164 major or all pagefaults. Default value is maj. 165 166--syscalls:: 167 Trace system calls. This options is enabled by default, disable with 168 --no-syscalls. 169 170--call-graph [mode,type,min[,limit],order[,key][,branch]]:: 171 Setup and enable call-graph (stack chain/backtrace) recording. 172 See `--call-graph` section in perf-record and perf-report 173 man pages for details. The ones that are most useful in 'perf trace' 174 are 'dwarf' and 'lbr', where available, try: 'perf trace --call-graph dwarf'. 175 176 Using this will, for the root user, bump the value of --mmap-pages to 4 177 times the maximum for non-root users, based on the kernel.perf_event_mlock_kb 178 sysctl. This is done only if the user doesn't specify a --mmap-pages value. 179 180--kernel-syscall-graph:: 181 Show the kernel callchains on the syscall exit path. 182 183--max-events=N:: 184 Stop after processing N events. Note that strace-like events are considered 185 only at exit time or when a syscall is interrupted, i.e. in those cases this 186 option is equivalent to the number of lines printed. 187 188--switch-on EVENT_NAME:: 189 Only consider events after this event is found. 190 191--switch-off EVENT_NAME:: 192 Stop considering events after this event is found. 193 194--show-on-off-events:: 195 Show the --switch-on/off events too. 196 197--max-stack:: 198 Set the stack depth limit when parsing the callchain, anything 199 beyond the specified depth will be ignored. Note that at this point 200 this is just about the presentation part, i.e. the kernel is still 201 not limiting, the overhead of callchains needs to be set via the 202 knobs in --call-graph dwarf. 203 204 Implies '--call-graph dwarf' when --call-graph not present on the 205 command line, on systems where DWARF unwinding was built in. 206 207 Default: /proc/sys/kernel/perf_event_max_stack when present for 208 live sessions (without --input/-i), 127 otherwise. 209 210--min-stack:: 211 Set the stack depth limit when parsing the callchain, anything 212 below the specified depth will be ignored. Disabled by default. 213 214 Implies '--call-graph dwarf' when --call-graph not present on the 215 command line, on systems where DWARF unwinding was built in. 216 217--print-sample:: 218 Print the PERF_RECORD_SAMPLE PERF_SAMPLE_ info for the 219 raw_syscalls:sys_{enter,exit} tracepoints, for debugging. 220 221--proc-map-timeout:: 222 When processing pre-existing threads /proc/XXX/mmap, it may take a long time, 223 because the file may be huge. A time out is needed in such cases. 224 This option sets the time out limit. The default value is 500 ms. 225 226--sort-events:: 227 Do sorting on batches of events, use when noticing out of order events that 228 may happen, for instance, when a thread gets migrated to a different CPU 229 while processing a syscall. 230 231--libtraceevent_print:: 232 Use libtraceevent to print tracepoint arguments. By default 'perf trace' uses 233 the same beautifiers used in the strace-like enter+exit lines to augment the 234 tracepoint arguments. 235 236--map-dump:: 237 Dump BPF maps setup by events passed via -e, for instance the augmented_raw_syscalls 238 living in tools/perf/examples/bpf/augmented_raw_syscalls.c. For now this 239 dumps just boolean map values and integer keys, in time this will print in hex 240 by default and use BTF when available, as well as use functions to do pretty 241 printing using the existing 'perf trace' syscall arg beautifiers to map integer 242 arguments to strings (pid to comm, syscall id to syscall name, etc). 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 250PAGEFAULTS 251---------- 252 253When tracing pagefaults, the format of the trace is as follows: 254 255<min|maj>fault [<ip.symbol>+<ip.offset>] => <[email protected]> (<map type><addr level>). 256 257- min/maj indicates whether fault event is minor or major; 258- ip.symbol shows symbol for instruction pointer (the code that generated the 259 fault); if no debug symbols available, perf trace will print raw IP; 260- addr.dso shows DSO for the faulted address; 261- map type is either 'd' for non-executable maps or 'x' for executable maps; 262- addr level is either 'k' for kernel dso or '.' for user dso. 263 264For symbols resolution you may need to install debugging symbols. 265 266Please be aware that duration is currently always 0 and doesn't reflect actual 267time it took for fault to be handled! 268 269When --verbose specified, perf trace tries to print all available information 270for both IP and fault address in the form of dso@symbol+offset. 271 272EXAMPLES 273-------- 274 275Trace only major pagefaults: 276 277 $ perf trace --no-syscalls -F 278 279Trace syscalls, major and minor pagefaults: 280 281 $ perf trace -F all 282 283 1416.547 ( 0.000 ms): python/20235 majfault [CRYPTO_push_info_+0x0] => /lib/x86_64-linux-gnu/libcrypto.so.1.0.0@0x61be0 (x.) 284 285 As you can see, there was major pagefault in python process, from 286 CRYPTO_push_info_ routine which faulted somewhere in libcrypto.so. 287 288Trace the first 4 open, openat or open_by_handle_at syscalls (in the future more syscalls may match here): 289 290 $ perf trace -e open* --max-events 4 291 [root@jouet perf]# trace -e open* --max-events 4 292 2272.992 ( 0.037 ms): gnome-shell/1370 openat(dfd: CWD, filename: /proc/self/stat) = 31 293 2277.481 ( 0.139 ms): gnome-shell/3039 openat(dfd: CWD, filename: /proc/self/stat) = 65 294 3026.398 ( 0.076 ms): gnome-shell/3039 openat(dfd: CWD, filename: /proc/self/stat) = 65 295 4294.665 ( 0.015 ms): sed/15879 openat(dfd: CWD, filename: /etc/ld.so.cache, flags: CLOEXEC) = 3 296 $ 297 298Trace the first minor page fault when running a workload: 299 300 # perf trace -F min --max-stack=7 --max-events 1 sleep 1 301 0.000 ( 0.000 ms): sleep/18006 minfault [__clear_user+0x1a] => 0x5626efa56080 (?k) 302 __clear_user ([kernel.kallsyms]) 303 load_elf_binary ([kernel.kallsyms]) 304 search_binary_handler ([kernel.kallsyms]) 305 __do_execve_file.isra.33 ([kernel.kallsyms]) 306 __x64_sys_execve ([kernel.kallsyms]) 307 do_syscall_64 ([kernel.kallsyms]) 308 entry_SYSCALL_64 ([kernel.kallsyms]) 309 # 310 311Trace the next min page page fault to take place on the first CPU: 312 313 # perf trace -F min --call-graph=dwarf --max-events 1 --cpu 0 314 0.000 ( 0.000 ms): Web Content/17136 minfault [js::gc::Chunk::fetchNextDecommittedArena+0x4b] => 0x7fbe6181b000 (?.) 315 js::gc::FreeSpan::initAsEmpty (inlined) 316 js::gc::Arena::setAsNotAllocated (inlined) 317 js::gc::Chunk::fetchNextDecommittedArena (/usr/lib64/firefox/libxul.so) 318 js::gc::Chunk::allocateArena (/usr/lib64/firefox/libxul.so) 319 js::gc::GCRuntime::allocateArena (/usr/lib64/firefox/libxul.so) 320 js::gc::ArenaLists::allocateFromArena (/usr/lib64/firefox/libxul.so) 321 js::gc::GCRuntime::tryNewTenuredThing<JSString, (js::AllowGC)1> (inlined) 322 js::AllocateString<JSString, (js::AllowGC)1> (/usr/lib64/firefox/libxul.so) 323 js::Allocate<JSThinInlineString, (js::AllowGC)1> (inlined) 324 JSThinInlineString::new_<(js::AllowGC)1> (inlined) 325 AllocateInlineString<(js::AllowGC)1, unsigned char> (inlined) 326 js::ConcatStrings<(js::AllowGC)1> (/usr/lib64/firefox/libxul.so) 327 [0x18b26e6bc2bd] (/tmp/perf-17136.map) 328 # 329 330Trace the next two sched:sched_switch events, four block:*_plug events, the 331next block:*_unplug and the next three net:*dev_queue events, this last one 332with a backtrace of at most 16 entries, system wide: 333 334 # perf trace -e sched:*switch/nr=2/,block:*_plug/nr=4/,block:*_unplug/nr=1/,net:*dev_queue/nr=3,max-stack=16/ 335 0.000 :0/0 sched:sched_switch:swapper/2:0 [120] S ==> rcu_sched:10 [120] 336 0.015 rcu_sched/10 sched:sched_switch:rcu_sched:10 [120] R ==> swapper/2:0 [120] 337 254.198 irq/50-iwlwifi/680 net:net_dev_queue:dev=wlp3s0 skbaddr=0xffff93498051f600 len=66 338 __dev_queue_xmit ([kernel.kallsyms]) 339 273.977 :0/0 net:net_dev_queue:dev=wlp3s0 skbaddr=0xffff93498051f600 len=78 340 __dev_queue_xmit ([kernel.kallsyms]) 341 274.007 :0/0 net:net_dev_queue:dev=wlp3s0 skbaddr=0xffff93498051ff00 len=78 342 __dev_queue_xmit ([kernel.kallsyms]) 343 2930.140 kworker/u16:58/2722 block:block_plug:[kworker/u16:58] 344 2930.162 kworker/u16:58/2722 block:block_unplug:[kworker/u16:58] 1 345 4466.094 jbd2/dm-2-8/748 block:block_plug:[jbd2/dm-2-8] 346 8050.123 kworker/u16:30/2694 block:block_plug:[kworker/u16:30] 347 8050.271 kworker/u16:30/2694 block:block_plug:[kworker/u16:30] 348 # 349 350SEE ALSO 351-------- 352linkperf:perf-record[1], linkperf:perf-script[1] 353