Manual: perf-trace

PERF-TRACE(1)						 perf Manual					       PERF-TRACE(1)

NAME
       perf-trace - strace inspired tool

SYNOPSIS
       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=
	   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
	   Increase the 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 in bytes with appended unit character -
	   B/K/M/G. The size is rounded up to the nearest power-of-two page 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.

       --summary-mode=mode
	   To be used with -s or -S, to select how to show summary. By default it’ll show the syscall summary by thread.
	   Possible values are: thread, total, cgroup.

       --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.

       --force-btf
	   Use btf_dump to pretty print syscall argument data, instead of using hand-crafted pretty printers. This option is
	   intended for testing BTF integration in perf trace. btf_dump-based pretty-printing serves as a fallback to
	   hand-crafted pretty printers, as the latter can better pretty-print integer flags and struct pointers.

       --bpf-summary
	   Collect system call statistics in BPF. This is only for live mode and works well with -s/--summary option where
	   no argument information is required.

       --max-summary=N
	   Maximum number of lines in the summary mode. Note that this applies to each entry (thread or cgroup).

PAGEFAULTS
       When tracing pagefaults, the format of the trace is as follows:

       fault [+] ⇒  (