NAME
perf-trace - strace inspired toolSYNOPSIS
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.OPTIONS
-a, --all-cpusSystem-wide collection from all CPUs.
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.
Event filter. This option should follow an event selector (-e) which selects tracepoint event(s).
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.
Output file name.
Record events on existing process ID (comma
separated list).
Record events on existing thread ID (comma
separated list).
Record events in threads owned by uid. Name or
number.
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 out events for these pids and for
trace itself (comma separated list).
Increase the verbosity level.
Child tasks do not inherit counters.
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.
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.
Show only events that had a duration greater
than N.M ms.
Accrue thread runtime and provide a summary at
the end of the session.
Show only syscalls that failed, i.e. that
returned < 0.
Process events from a given perf data
file.
Print full timestamp rather time relative to
first sample.
Show process COMM right beside its ID, on by
default, disable with --no-comm.
Show only a summary of syscalls by thread with
min, max, and average times (in msec) and relative stddev.
Show all syscalls followed by a summary by
thread with min, max, and average times (in msec) and relative stddev.
To be used with -s or -S, to show stats for
the errnos experienced by syscalls, using only this option will trigger
--summary.
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.
Don’t complain, do it.
Trace pagefaults. Optionally, you can specify
whether you want minor, major or all pagefaults. Default value is maj.
Trace system calls. This options is enabled by
default, disable with --no-syscalls.
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.
Show the kernel callchains on the syscall exit
path.
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.
Only consider events after this event is
found.
Stop considering events after this event is
found.
Show the --switch-on/off events too.
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.
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 the PERF_RECORD_SAMPLE PERF_SAMPLE_ info
for the raw_syscalls:sys_{enter,exit} tracepoints, for debugging.
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.
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.
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.
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 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.
EXAMPLES
Trace only major pagefaults:$ perf trace --no-syscalls -F
$ 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.
$ 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 $
# 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]) #
# 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) #
# 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
perf-record(1), perf-script(1)2024-06-21 | perf |