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 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 with appended unit character - B/K/M/G. The 110 size is rounded up to have nearest pages power of two 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--tool_stats:: 150 Show tool stats such as number of times fd->pathname was discovered thru 151 hooking the open syscall return + vfs_getname or via reading /proc/pid/fd, etc. 152 153-f:: 154--force:: 155 Don't complain, do it. 156 157-F=[all|min|maj]:: 158--pf=[all|min|maj]:: 159 Trace pagefaults. Optionally, you can specify whether you want minor, 160 major or all pagefaults. Default value is maj. 161 162--syscalls:: 163 Trace system calls. This options is enabled by default, disable with 164 --no-syscalls. 165 166--call-graph [mode,type,min[,limit],order[,key][,branch]]:: 167 Setup and enable call-graph (stack chain/backtrace) recording. 168 See `--call-graph` section in perf-record and perf-report 169 man pages for details. The ones that are most useful in 'perf trace' 170 are 'dwarf' and 'lbr', where available, try: 'perf trace --call-graph dwarf'. 171 172 Using this will, for the root user, bump the value of --mmap-pages to 4 173 times the maximum for non-root users, based on the kernel.perf_event_mlock_kb 174 sysctl. This is done only if the user doesn't specify a --mmap-pages value. 175 176--kernel-syscall-graph:: 177 Show the kernel callchains on the syscall exit path. 178 179--max-events=N:: 180 Stop after processing N events. Note that strace-like events are considered 181 only at exit time or when a syscall is interrupted, i.e. in those cases this 182 option is equivalent to the number of lines printed. 183 184--switch-on EVENT_NAME:: 185 Only consider events after this event is found. 186 187--switch-off EVENT_NAME:: 188 Stop considering events after this event is found. 189 190--show-on-off-events:: 191 Show the --switch-on/off events too. 192 193--max-stack:: 194 Set the stack depth limit when parsing the callchain, anything 195 beyond the specified depth will be ignored. Note that at this point 196 this is just about the presentation part, i.e. the kernel is still 197 not limiting, the overhead of callchains needs to be set via the 198 knobs in --call-graph dwarf. 199 200 Implies '--call-graph dwarf' when --call-graph not present on the 201 command line, on systems where DWARF unwinding was built in. 202 203 Default: /proc/sys/kernel/perf_event_max_stack when present for 204 live sessions (without --input/-i), 127 otherwise. 205 206--min-stack:: 207 Set the stack depth limit when parsing the callchain, anything 208 below the specified depth will be ignored. Disabled by default. 209 210 Implies '--call-graph dwarf' when --call-graph not present on the 211 command line, on systems where DWARF unwinding was built in. 212 213--print-sample:: 214 Print the PERF_RECORD_SAMPLE PERF_SAMPLE_ info for the 215 raw_syscalls:sys_{enter,exit} tracepoints, for debugging. 216 217--proc-map-timeout:: 218 When processing pre-existing threads /proc/XXX/mmap, it may take a long time, 219 because the file may be huge. A time out is needed in such cases. 220 This option sets the time out limit. The default value is 500 ms. 221 222--sort-events:: 223 Do sorting on batches of events, use when noticing out of order events that 224 may happen, for instance, when a thread gets migrated to a different CPU 225 while processing a syscall. 226 227--libtraceevent_print:: 228 Use libtraceevent to print tracepoint arguments. By default 'perf trace' uses 229 the same beautifiers used in the strace-like enter+exit lines to augment the 230 tracepoint arguments. 231 232--map-dump:: 233 Dump BPF maps setup by events passed via -e, for instance the augmented_raw_syscalls 234 living in tools/perf/examples/bpf/augmented_raw_syscalls.c. For now this 235 dumps just boolean map values and integer keys, in time this will print in hex 236 by default and use BTF when available, as well as use functions to do pretty 237 printing using the existing 'perf trace' syscall arg beautifiers to map integer 238 arguments to strings (pid to comm, syscall id to syscall name, etc). 239 240 241PAGEFAULTS 242---------- 243 244When tracing pagefaults, the format of the trace is as follows: 245 246<min|maj>fault [<ip.symbol>+<ip.offset>] => <addr.dso@addr.offset> (<map type><addr level>). 247 248- min/maj indicates whether fault event is minor or major; 249- ip.symbol shows symbol for instruction pointer (the code that generated the 250 fault); if no debug symbols available, perf trace will print raw IP; 251- addr.dso shows DSO for the faulted address; 252- map type is either 'd' for non-executable maps or 'x' for executable maps; 253- addr level is either 'k' for kernel dso or '.' for user dso. 254 255For symbols resolution you may need to install debugging symbols. 256 257Please be aware that duration is currently always 0 and doesn't reflect actual 258time it took for fault to be handled! 259 260When --verbose specified, perf trace tries to print all available information 261for both IP and fault address in the form of dso@symbol+offset. 262 263EXAMPLES 264-------- 265 266Trace only major pagefaults: 267 268 $ perf trace --no-syscalls -F 269 270Trace syscalls, major and minor pagefaults: 271 272 $ perf trace -F all 273 274 1416.547 ( 0.000 ms): python/20235 majfault [CRYPTO_push_info_+0x0] => /lib/x86_64-linux-gnu/libcrypto.so.1.0.0@0x61be0 (x.) 275 276 As you can see, there was major pagefault in python process, from 277 CRYPTO_push_info_ routine which faulted somewhere in libcrypto.so. 278 279Trace the first 4 open, openat or open_by_handle_at syscalls (in the future more syscalls may match here): 280 281 $ perf trace -e open* --max-events 4 282 [root@jouet perf]# trace -e open* --max-events 4 283 2272.992 ( 0.037 ms): gnome-shell/1370 openat(dfd: CWD, filename: /proc/self/stat) = 31 284 2277.481 ( 0.139 ms): gnome-shell/3039 openat(dfd: CWD, filename: /proc/self/stat) = 65 285 3026.398 ( 0.076 ms): gnome-shell/3039 openat(dfd: CWD, filename: /proc/self/stat) = 65 286 4294.665 ( 0.015 ms): sed/15879 openat(dfd: CWD, filename: /etc/ld.so.cache, flags: CLOEXEC) = 3 287 $ 288 289Trace the first minor page fault when running a workload: 290 291 # perf trace -F min --max-stack=7 --max-events 1 sleep 1 292 0.000 ( 0.000 ms): sleep/18006 minfault [__clear_user+0x1a] => 0x5626efa56080 (?k) 293 __clear_user ([kernel.kallsyms]) 294 load_elf_binary ([kernel.kallsyms]) 295 search_binary_handler ([kernel.kallsyms]) 296 __do_execve_file.isra.33 ([kernel.kallsyms]) 297 __x64_sys_execve ([kernel.kallsyms]) 298 do_syscall_64 ([kernel.kallsyms]) 299 entry_SYSCALL_64 ([kernel.kallsyms]) 300 # 301 302Trace the next min page page fault to take place on the first CPU: 303 304 # perf trace -F min --call-graph=dwarf --max-events 1 --cpu 0 305 0.000 ( 0.000 ms): Web Content/17136 minfault [js::gc::Chunk::fetchNextDecommittedArena+0x4b] => 0x7fbe6181b000 (?.) 306 js::gc::FreeSpan::initAsEmpty (inlined) 307 js::gc::Arena::setAsNotAllocated (inlined) 308 js::gc::Chunk::fetchNextDecommittedArena (/usr/lib64/firefox/libxul.so) 309 js::gc::Chunk::allocateArena (/usr/lib64/firefox/libxul.so) 310 js::gc::GCRuntime::allocateArena (/usr/lib64/firefox/libxul.so) 311 js::gc::ArenaLists::allocateFromArena (/usr/lib64/firefox/libxul.so) 312 js::gc::GCRuntime::tryNewTenuredThing<JSString, (js::AllowGC)1> (inlined) 313 js::AllocateString<JSString, (js::AllowGC)1> (/usr/lib64/firefox/libxul.so) 314 js::Allocate<JSThinInlineString, (js::AllowGC)1> (inlined) 315 JSThinInlineString::new_<(js::AllowGC)1> (inlined) 316 AllocateInlineString<(js::AllowGC)1, unsigned char> (inlined) 317 js::ConcatStrings<(js::AllowGC)1> (/usr/lib64/firefox/libxul.so) 318 [0x18b26e6bc2bd] (/tmp/perf-17136.map) 319 # 320 321Trace the next two sched:sched_switch events, four block:*_plug events, the 322next block:*_unplug and the next three net:*dev_queue events, this last one 323with a backtrace of at most 16 entries, system wide: 324 325 # perf trace -e sched:*switch/nr=2/,block:*_plug/nr=4/,block:*_unplug/nr=1/,net:*dev_queue/nr=3,max-stack=16/ 326 0.000 :0/0 sched:sched_switch:swapper/2:0 [120] S ==> rcu_sched:10 [120] 327 0.015 rcu_sched/10 sched:sched_switch:rcu_sched:10 [120] R ==> swapper/2:0 [120] 328 254.198 irq/50-iwlwifi/680 net:net_dev_queue:dev=wlp3s0 skbaddr=0xffff93498051f600 len=66 329 __dev_queue_xmit ([kernel.kallsyms]) 330 273.977 :0/0 net:net_dev_queue:dev=wlp3s0 skbaddr=0xffff93498051f600 len=78 331 __dev_queue_xmit ([kernel.kallsyms]) 332 274.007 :0/0 net:net_dev_queue:dev=wlp3s0 skbaddr=0xffff93498051ff00 len=78 333 __dev_queue_xmit ([kernel.kallsyms]) 334 2930.140 kworker/u16:58/2722 block:block_plug:[kworker/u16:58] 335 2930.162 kworker/u16:58/2722 block:block_unplug:[kworker/u16:58] 1 336 4466.094 jbd2/dm-2-8/748 block:block_plug:[jbd2/dm-2-8] 337 8050.123 kworker/u16:30/2694 block:block_plug:[kworker/u16:30] 338 8050.271 kworker/u16:30/2694 block:block_plug:[kworker/u16:30] 339 # 340 341SEE ALSO 342-------- 343linkperf:perf-record[1], linkperf:perf-script[1] 344