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 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--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
245PAGEFAULTS
246----------
247
248When tracing pagefaults, the format of the trace is as follows:
249
250<min|maj>fault [<ip.symbol>+<ip.offset>] => <addr.dso@addr.offset> (<map type><addr level>).
251
252- min/maj indicates whether fault event is minor or major;
253- ip.symbol shows symbol for instruction pointer (the code that generated the
254  fault); if no debug symbols available, perf trace will print raw IP;
255- addr.dso shows DSO for the faulted address;
256- map type is either 'd' for non-executable maps or 'x' for executable maps;
257- addr level is either 'k' for kernel dso or '.' for user dso.
258
259For symbols resolution you may need to install debugging symbols.
260
261Please be aware that duration is currently always 0 and doesn't reflect actual
262time it took for fault to be handled!
263
264When --verbose specified, perf trace tries to print all available information
265for both IP and fault address in the form of dso@symbol+offset.
266
267EXAMPLES
268--------
269
270Trace only major pagefaults:
271
272 $ perf trace --no-syscalls -F
273
274Trace syscalls, major and minor pagefaults:
275
276 $ perf trace -F all
277
278  1416.547 ( 0.000 ms): python/20235 majfault [CRYPTO_push_info_+0x0] => /lib/x86_64-linux-gnu/libcrypto.so.1.0.0@0x61be0 (x.)
279
280  As you can see, there was major pagefault in python process, from
281  CRYPTO_push_info_ routine which faulted somewhere in libcrypto.so.
282
283Trace the first 4 open, openat or open_by_handle_at syscalls (in the future more syscalls may match here):
284
285  $ perf trace -e open* --max-events 4
286  [root@jouet perf]# trace -e open* --max-events 4
287  2272.992 ( 0.037 ms): gnome-shell/1370 openat(dfd: CWD, filename: /proc/self/stat) = 31
288  2277.481 ( 0.139 ms): gnome-shell/3039 openat(dfd: CWD, filename: /proc/self/stat) = 65
289  3026.398 ( 0.076 ms): gnome-shell/3039 openat(dfd: CWD, filename: /proc/self/stat) = 65
290  4294.665 ( 0.015 ms): sed/15879 openat(dfd: CWD, filename: /etc/ld.so.cache, flags: CLOEXEC) = 3
291  $
292
293Trace the first minor page fault when running a workload:
294
295  # perf trace -F min --max-stack=7 --max-events 1 sleep 1
296     0.000 ( 0.000 ms): sleep/18006 minfault [__clear_user+0x1a] => 0x5626efa56080 (?k)
297                                       __clear_user ([kernel.kallsyms])
298                                       load_elf_binary ([kernel.kallsyms])
299                                       search_binary_handler ([kernel.kallsyms])
300                                       __do_execve_file.isra.33 ([kernel.kallsyms])
301                                       __x64_sys_execve ([kernel.kallsyms])
302                                       do_syscall_64 ([kernel.kallsyms])
303                                       entry_SYSCALL_64 ([kernel.kallsyms])
304  #
305
306Trace the next min page page fault to take place on the first CPU:
307
308  # perf trace -F min --call-graph=dwarf --max-events 1 --cpu 0
309     0.000 ( 0.000 ms): Web Content/17136 minfault [js::gc::Chunk::fetchNextDecommittedArena+0x4b] => 0x7fbe6181b000 (?.)
310                                       js::gc::FreeSpan::initAsEmpty (inlined)
311                                       js::gc::Arena::setAsNotAllocated (inlined)
312                                       js::gc::Chunk::fetchNextDecommittedArena (/usr/lib64/firefox/libxul.so)
313                                       js::gc::Chunk::allocateArena (/usr/lib64/firefox/libxul.so)
314                                       js::gc::GCRuntime::allocateArena (/usr/lib64/firefox/libxul.so)
315                                       js::gc::ArenaLists::allocateFromArena (/usr/lib64/firefox/libxul.so)
316                                       js::gc::GCRuntime::tryNewTenuredThing<JSString, (js::AllowGC)1> (inlined)
317                                       js::AllocateString<JSString, (js::AllowGC)1> (/usr/lib64/firefox/libxul.so)
318                                       js::Allocate<JSThinInlineString, (js::AllowGC)1> (inlined)
319                                       JSThinInlineString::new_<(js::AllowGC)1> (inlined)
320                                       AllocateInlineString<(js::AllowGC)1, unsigned char> (inlined)
321                                       js::ConcatStrings<(js::AllowGC)1> (/usr/lib64/firefox/libxul.so)
322                                       [0x18b26e6bc2bd] (/tmp/perf-17136.map)
323  #
324
325Trace the next two sched:sched_switch events, four block:*_plug events, the
326next block:*_unplug and the next three net:*dev_queue events, this last one
327with a backtrace of at most 16 entries, system wide:
328
329  # perf trace -e sched:*switch/nr=2/,block:*_plug/nr=4/,block:*_unplug/nr=1/,net:*dev_queue/nr=3,max-stack=16/
330     0.000 :0/0 sched:sched_switch:swapper/2:0 [120] S ==> rcu_sched:10 [120]
331     0.015 rcu_sched/10 sched:sched_switch:rcu_sched:10 [120] R ==> swapper/2:0 [120]
332   254.198 irq/50-iwlwifi/680 net:net_dev_queue:dev=wlp3s0 skbaddr=0xffff93498051f600 len=66
333                                       __dev_queue_xmit ([kernel.kallsyms])
334   273.977 :0/0 net:net_dev_queue:dev=wlp3s0 skbaddr=0xffff93498051f600 len=78
335                                       __dev_queue_xmit ([kernel.kallsyms])
336   274.007 :0/0 net:net_dev_queue:dev=wlp3s0 skbaddr=0xffff93498051ff00 len=78
337                                       __dev_queue_xmit ([kernel.kallsyms])
338  2930.140 kworker/u16:58/2722 block:block_plug:[kworker/u16:58]
339  2930.162 kworker/u16:58/2722 block:block_unplug:[kworker/u16:58] 1
340  4466.094 jbd2/dm-2-8/748 block:block_plug:[jbd2/dm-2-8]
341  8050.123 kworker/u16:30/2694 block:block_plug:[kworker/u16:30]
342  8050.271 kworker/u16:30/2694 block:block_plug:[kworker/u16:30]
343  #
344
345SEE ALSO
346--------
347linkperf:perf-record[1], linkperf:perf-script[1]
348