Provided by: linux-xilinx-zynqmp-tools-common_5.15.0-1031.35_all bug


       perf-trace - strace inspired tool


       perf trace
       perf trace record


       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 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.


       -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.

           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 out events for these pids and for trace itself (comma separated list).

       -v, --verbose
           Increase the verbosity level.

           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

       -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.

           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.

       -i, --input
           Process events from a given perf data file.

       -T, --time
           Print full timestamp rather time relative to first sample.

           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.

           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.

       -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.

           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

               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.

       --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 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

           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).


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

       <min|maj>fault [<ip.symbol>+<ip.offset>] ⇒ <addr.dso@addr.offset[1]> (<map type><addr

       •   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[2]+offset.


       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/ (x.)

           As you can see, there was major pagefault in python process, from
           CRYPTO_push_info_ routine which faulted somewhere in

       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/, 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/
                                                js::gc::Chunk::allocateArena (/usr/lib64/firefox/
                                                js::gc::GCRuntime::allocateArena (/usr/lib64/firefox/
                                                js::gc::ArenaLists::allocateFromArena (/usr/lib64/firefox/
                                                js::gc::GCRuntime::tryNewTenuredThing<JSString, (js::AllowGC)1> (inlined)
                                                js::AllocateString<JSString, (js::AllowGC)1> (/usr/lib64/firefox/
                                                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/
                                                [0x18b26e6bc2bd] (/tmp/

       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]


       perf-record(1), perf-script(1)


        1. addr.dso@addr.offset

        2. dso@symbol