perf-trace(1)
|
=============
|
|
NAME
|
----
|
perf-trace - strace inspired tool
|
|
SYNOPSIS
|
--------
|
[verse]
|
'perf trace'
|
'perf trace record'
|
|
DESCRIPTION
|
-----------
|
This command will show the events associated with the target, initially
|
syscalls, but other system events like pagefaults, task lifetime events,
|
scheduling events, etc.
|
|
This is a live mode tool in addition to working with perf.data files like
|
the other perf tools. Files can be generated using the 'perf record' command
|
but the session needs to include the raw_syscalls events (-e 'raw_syscalls:*').
|
Alternatively, 'perf trace record' can be used as a shortcut to
|
automatically include the raw_syscalls events when writing events to a file.
|
|
The following options apply to perf trace; options to perf trace record are
|
found in the perf record man page.
|
|
OPTIONS
|
-------
|
|
-a::
|
--all-cpus::
|
System-wide collection from all CPUs.
|
|
-e::
|
--expr::
|
--event::
|
List of syscalls and other perf events (tracepoints, HW cache events,
|
etc) to show. Globbing is supported, e.g.: "epoll_*", "*msg*", etc.
|
See 'perf list' for a complete list of events.
|
Prefixing with ! shows all syscalls but the ones specified. You may
|
need to escape it.
|
|
--filter=<filter>::
|
Event filter. This option should follow an event selector (-e) which
|
selects tracepoint event(s).
|
|
|
-D msecs::
|
--delay msecs::
|
After starting the program, wait msecs before measuring. This is useful to
|
filter out the startup phase of the program, which is often very different.
|
|
-o::
|
--output=::
|
Output file name.
|
|
-p::
|
--pid=::
|
Record events on existing process ID (comma separated list).
|
|
-t::
|
--tid=::
|
Record events on existing thread ID (comma separated list).
|
|
-u::
|
--uid=::
|
Record events in threads owned by uid. Name or number.
|
|
-G::
|
--cgroup::
|
Record events in threads in a cgroup.
|
|
Look for cgroups to set at the /sys/fs/cgroup/perf_event directory, then
|
remove the /sys/fs/cgroup/perf_event/ part and try:
|
|
perf trace -G A -e sched:*switch
|
|
Will set all raw_syscalls:sys_{enter,exit}, pgfault, vfs_getname, etc
|
_and_ sched:sched_switch to the 'A' cgroup, while:
|
|
perf trace -e sched:*switch -G A
|
|
will only set the sched:sched_switch event to the 'A' cgroup, all the
|
other events (raw_syscalls:sys_{enter,exit}, etc are left "without"
|
a cgroup (on the root cgroup, sys wide, etc).
|
|
Multiple cgroups:
|
|
perf trace -G A -e sched:*switch -G B
|
|
the syscall ones go to the 'A' cgroup, the sched:sched_switch goes
|
to the 'B' cgroup.
|
|
--filter-pids=::
|
Filter out events for these pids and for 'trace' itself (comma separated list).
|
|
-v::
|
--verbose=::
|
Verbosity level.
|
|
--no-inherit::
|
Child tasks do not inherit counters.
|
|
-m::
|
--mmap-pages=::
|
Number of mmap data pages (must be a power of two) or size
|
specification with appended unit character - B/K/M/G. The
|
size is rounded up to have nearest pages power of two value.
|
|
-C::
|
--cpu::
|
Collect samples only on the list of CPUs provided. Multiple CPUs can be provided as a
|
comma-separated list with no space: 0,1. Ranges of CPUs are specified with -: 0-2.
|
In per-thread mode with inheritance mode on (default), Events are captured only when
|
the thread executes on the designated CPUs. Default is to monitor all CPUs.
|
|
--duration::
|
Show only events that had a duration greater than N.M ms.
|
|
--sched::
|
Accrue thread runtime and provide a summary at the end of the session.
|
|
--failure::
|
Show only syscalls that failed, i.e. that returned < 0.
|
|
-i::
|
--input::
|
Process events from a given perf data file.
|
|
-T::
|
--time::
|
Print full timestamp rather time relative to first sample.
|
|
--comm::
|
Show process COMM right beside its ID, on by default, disable with --no-comm.
|
|
-s::
|
--summary::
|
Show only a summary of syscalls by thread with min, max, and average times
|
(in msec) and relative stddev.
|
|
-S::
|
--with-summary::
|
Show all syscalls followed by a summary by thread with min, max, and
|
average times (in msec) and relative stddev.
|
|
--errno-summary::
|
To be used with -s or -S, to show stats for the errnos experienced by
|
syscalls, using only this option will trigger --summary.
|
|
--tool_stats::
|
Show tool stats such as number of times fd->pathname was discovered thru
|
hooking the open syscall return + vfs_getname or via reading /proc/pid/fd, etc.
|
|
-f::
|
--force::
|
Don't complain, do it.
|
|
-F=[all|min|maj]::
|
--pf=[all|min|maj]::
|
Trace pagefaults. Optionally, you can specify whether you want minor,
|
major or all pagefaults. Default value is maj.
|
|
--syscalls::
|
Trace system calls. This options is enabled by default, disable with
|
--no-syscalls.
|
|
--call-graph [mode,type,min[,limit],order[,key][,branch]]::
|
Setup and enable call-graph (stack chain/backtrace) recording.
|
See `--call-graph` section in perf-record and perf-report
|
man pages for details. The ones that are most useful in 'perf trace'
|
are 'dwarf' and 'lbr', where available, try: 'perf trace --call-graph dwarf'.
|
|
Using this will, for the root user, bump the value of --mmap-pages to 4
|
times the maximum for non-root users, based on the kernel.perf_event_mlock_kb
|
sysctl. This is done only if the user doesn't specify a --mmap-pages value.
|
|
--kernel-syscall-graph::
|
Show the kernel callchains on the syscall exit path.
|
|
--max-events=N::
|
Stop after processing N events. Note that strace-like events are considered
|
only at exit time or when a syscall is interrupted, i.e. in those cases this
|
option is equivalent to the number of lines printed.
|
|
--switch-on EVENT_NAME::
|
Only consider events after this event is found.
|
|
--switch-off EVENT_NAME::
|
Stop considering events after this event is found.
|
|
--show-on-off-events::
|
Show the --switch-on/off events too.
|
|
--max-stack::
|
Set the stack depth limit when parsing the callchain, anything
|
beyond the specified depth will be ignored. Note that at this point
|
this is just about the presentation part, i.e. the kernel is still
|
not limiting, the overhead of callchains needs to be set via the
|
knobs in --call-graph dwarf.
|
|
Implies '--call-graph dwarf' when --call-graph not present on the
|
command line, on systems where DWARF unwinding was built in.
|
|
Default: /proc/sys/kernel/perf_event_max_stack when present for
|
live sessions (without --input/-i), 127 otherwise.
|
|
--min-stack::
|
Set the stack depth limit when parsing the callchain, anything
|
below the specified depth will be ignored. Disabled by default.
|
|
Implies '--call-graph dwarf' when --call-graph not present on the
|
command line, on systems where DWARF unwinding was built in.
|
|
--print-sample::
|
Print the PERF_RECORD_SAMPLE PERF_SAMPLE_ info for the
|
raw_syscalls:sys_{enter,exit} tracepoints, for debugging.
|
|
--proc-map-timeout::
|
When processing pre-existing threads /proc/XXX/mmap, it may take a long time,
|
because the file may be huge. A time out is needed in such cases.
|
This option sets the time out limit. The default value is 500 ms.
|
|
--sort-events::
|
Do sorting on batches of events, use when noticing out of order events that
|
may happen, for instance, when a thread gets migrated to a different CPU
|
while processing a syscall.
|
|
--libtraceevent_print::
|
Use libtraceevent to print tracepoint arguments. By default 'perf trace' uses
|
the same beautifiers used in the strace-like enter+exit lines to augment the
|
tracepoint arguments.
|
|
--map-dump::
|
Dump BPF maps setup by events passed via -e, for instance the augmented_raw_syscalls
|
living in tools/perf/examples/bpf/augmented_raw_syscalls.c. For now this
|
dumps just boolean map values and integer keys, in time this will print in hex
|
by default and use BTF when available, as well as use functions to do pretty
|
printing using the existing 'perf trace' syscall arg beautifiers to map integer
|
arguments to strings (pid to comm, syscall id to syscall name, etc).
|
|
|
PAGEFAULTS
|
----------
|
|
When tracing pagefaults, the format of the trace is as follows:
|
|
<min|maj>fault [<ip.symbol>+<ip.offset>] => <addr.dso@addr.offset> (<map type><addr level>).
|
|
- min/maj indicates whether fault event is minor or major;
|
- ip.symbol shows symbol for instruction pointer (the code that generated the
|
fault); if no debug symbols available, perf trace will print raw IP;
|
- addr.dso shows DSO for the faulted address;
|
- map type is either 'd' for non-executable maps or 'x' for executable maps;
|
- addr level is either 'k' for kernel dso or '.' for user dso.
|
|
For symbols resolution you may need to install debugging symbols.
|
|
Please be aware that duration is currently always 0 and doesn't reflect actual
|
time it took for fault to be handled!
|
|
When --verbose specified, perf trace tries to print all available information
|
for both IP and fault address in the form of dso@symbol+offset.
|
|
EXAMPLES
|
--------
|
|
Trace only major pagefaults:
|
|
$ perf trace --no-syscalls -F
|
|
Trace syscalls, major and minor pagefaults:
|
|
$ perf trace -F all
|
|
1416.547 ( 0.000 ms): python/20235 majfault [CRYPTO_push_info_+0x0] => /lib/x86_64-linux-gnu/libcrypto.so.1.0.0@0x61be0 (x.)
|
|
As you can see, there was major pagefault in python process, from
|
CRYPTO_push_info_ routine which faulted somewhere in libcrypto.so.
|
|
Trace the first 4 open, openat or open_by_handle_at syscalls (in the future more syscalls may match here):
|
|
$ perf trace -e open* --max-events 4
|
[root@jouet perf]# trace -e open* --max-events 4
|
2272.992 ( 0.037 ms): gnome-shell/1370 openat(dfd: CWD, filename: /proc/self/stat) = 31
|
2277.481 ( 0.139 ms): gnome-shell/3039 openat(dfd: CWD, filename: /proc/self/stat) = 65
|
3026.398 ( 0.076 ms): gnome-shell/3039 openat(dfd: CWD, filename: /proc/self/stat) = 65
|
4294.665 ( 0.015 ms): sed/15879 openat(dfd: CWD, filename: /etc/ld.so.cache, flags: CLOEXEC) = 3
|
$
|
|
Trace the first minor page fault when running a workload:
|
|
# perf trace -F min --max-stack=7 --max-events 1 sleep 1
|
0.000 ( 0.000 ms): sleep/18006 minfault [__clear_user+0x1a] => 0x5626efa56080 (?k)
|
__clear_user ([kernel.kallsyms])
|
load_elf_binary ([kernel.kallsyms])
|
search_binary_handler ([kernel.kallsyms])
|
__do_execve_file.isra.33 ([kernel.kallsyms])
|
__x64_sys_execve ([kernel.kallsyms])
|
do_syscall_64 ([kernel.kallsyms])
|
entry_SYSCALL_64 ([kernel.kallsyms])
|
#
|
|
Trace the next min page page fault to take place on the first CPU:
|
|
# perf trace -F min --call-graph=dwarf --max-events 1 --cpu 0
|
0.000 ( 0.000 ms): Web Content/17136 minfault [js::gc::Chunk::fetchNextDecommittedArena+0x4b] => 0x7fbe6181b000 (?.)
|
js::gc::FreeSpan::initAsEmpty (inlined)
|
js::gc::Arena::setAsNotAllocated (inlined)
|
js::gc::Chunk::fetchNextDecommittedArena (/usr/lib64/firefox/libxul.so)
|
js::gc::Chunk::allocateArena (/usr/lib64/firefox/libxul.so)
|
js::gc::GCRuntime::allocateArena (/usr/lib64/firefox/libxul.so)
|
js::gc::ArenaLists::allocateFromArena (/usr/lib64/firefox/libxul.so)
|
js::gc::GCRuntime::tryNewTenuredThing<JSString, (js::AllowGC)1> (inlined)
|
js::AllocateString<JSString, (js::AllowGC)1> (/usr/lib64/firefox/libxul.so)
|
js::Allocate<JSThinInlineString, (js::AllowGC)1> (inlined)
|
JSThinInlineString::new_<(js::AllowGC)1> (inlined)
|
AllocateInlineString<(js::AllowGC)1, unsigned char> (inlined)
|
js::ConcatStrings<(js::AllowGC)1> (/usr/lib64/firefox/libxul.so)
|
[0x18b26e6bc2bd] (/tmp/perf-17136.map)
|
#
|
|
Trace the next two sched:sched_switch events, four block:*_plug events, the
|
next block:*_unplug and the next three net:*dev_queue events, this last one
|
with a backtrace of at most 16 entries, system wide:
|
|
# perf trace -e sched:*switch/nr=2/,block:*_plug/nr=4/,block:*_unplug/nr=1/,net:*dev_queue/nr=3,max-stack=16/
|
0.000 :0/0 sched:sched_switch:swapper/2:0 [120] S ==> rcu_sched:10 [120]
|
0.015 rcu_sched/10 sched:sched_switch:rcu_sched:10 [120] R ==> swapper/2:0 [120]
|
254.198 irq/50-iwlwifi/680 net:net_dev_queue:dev=wlp3s0 skbaddr=0xffff93498051f600 len=66
|
__dev_queue_xmit ([kernel.kallsyms])
|
273.977 :0/0 net:net_dev_queue:dev=wlp3s0 skbaddr=0xffff93498051f600 len=78
|
__dev_queue_xmit ([kernel.kallsyms])
|
274.007 :0/0 net:net_dev_queue:dev=wlp3s0 skbaddr=0xffff93498051ff00 len=78
|
__dev_queue_xmit ([kernel.kallsyms])
|
2930.140 kworker/u16:58/2722 block:block_plug:[kworker/u16:58]
|
2930.162 kworker/u16:58/2722 block:block_unplug:[kworker/u16:58] 1
|
4466.094 jbd2/dm-2-8/748 block:block_plug:[jbd2/dm-2-8]
|
8050.123 kworker/u16:30/2694 block:block_plug:[kworker/u16:30]
|
8050.271 kworker/u16:30/2694 block:block_plug:[kworker/u16:30]
|
#
|
|
SEE ALSO
|
--------
|
linkperf:perf-record[1], linkperf:perf-script[1]
|
