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