perf-lock(1)
============

NAME
----
perf-lock - Analyze lock events

SYNOPSIS
--------
[verse]
'perf lock' {record|report|script|info|contention}

DESCRIPTION
-----------
You can analyze various lock behaviours
and statistics with this 'perf lock' command.

  'perf lock record <command>' records lock events
  between start and end <command>. And this command
  produces the file "perf.data" which contains tracing
  results of lock events.

  'perf lock report' reports statistical data.

  'perf lock script' shows raw lock events.

  'perf lock info' shows metadata like threads or addresses
  of lock instances.

  'perf lock contention' shows contention statistics.

COMMON OPTIONS
--------------

-i::
--input=<file>::
        Input file name. (default: perf.data unless stdin is a fifo)

--output=<file>::
        Output file name for perf lock contention and report.

-v::
--verbose::
        Be more verbose (show symbol address, etc).

-q::
--quiet::
	Do not show any warnings or messages. (Suppress -v)

-D::
--dump-raw-trace::
        Dump raw trace in ASCII.

-f::
--force::
	Don't complain, do it.

--vmlinux=<file>::
        vmlinux pathname

--kallsyms=<file>::
        kallsyms pathname


REPORT OPTIONS
--------------

-k::
--key=<value>::
        Sorting key. Possible values: acquired (default), contended,
	avg_wait, wait_total, wait_max, wait_min.

-F::
--field=<value>::
        Output fields. By default it shows all the fields but users can
	customize that using this.  Possible values: acquired, contended,
	avg_wait, wait_total, wait_max, wait_min.

-c::
--combine-locks::
	Merge lock instances in the same class (based on name).

-t::
--threads::
    The -t option is to show per-thread lock stat like below:

      $ perf lock report -t -F acquired,contended,avg_wait

                    Name   acquired  contended   avg wait (ns)

                    perf     240569          9            5784
                 swapper     106610         19             543
                  :15789      17370          2           14538
            ContainerMgr       8981          6             874
                   sleep       5275          1           11281
         ContainerThread       4416          4             944
         RootPressureThr       3215          5            1215
             rcu_preempt       2954          0               0
            ContainerMgr       2560          0               0
                 unnamed       1873          0               0
         EventManager_De       1845          1             636
         futex-default-S       1609          0               0

-E::
--entries=<value>::
	Display this many entries.


INFO OPTIONS
------------

-t::
--threads::
	dump only the thread list in perf.data

-m::
--map::
	dump only the map of lock instances (address:name table)


CONTENTION OPTIONS
------------------

-k::
--key=<value>::
	Sorting key. Possible values: contended, wait_total (default),
	wait_max, wait_min, avg_wait.

-F::
--field=<value>::
	Output fields. By default it shows all but the wait_min fields
	and users can customize that using this.  Possible values:
	contended, wait_total, wait_max, wait_min, avg_wait.

-t::
--threads::
	Show per-thread lock contention stat

-b::
--use-bpf::
	Use BPF program to collect lock contention stats instead of
	using the input data.

-a::
--all-cpus::
        System-wide collection from all CPUs.

-C::
--cpu=<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.  Default is to monitor all CPUs.

-p::
--pid=<value>::
	Record events on existing process ID (comma separated list).

--tid=<value>::
        Record events on existing thread ID (comma separated list).

-M::
--map-nr-entries=<value>::
	Maximum number of BPF map entries (default: 16384).
	This will be aligned to a power of 2.

--max-stack=<value>::
	Maximum stack depth when collecting lock contention (default: 8).

--stack-skip=<value>::
	Number of stack depth to skip when finding a lock caller (default: 3).

-E::
--entries=<value>::
	Display this many entries.

-l::
--lock-addr::
	Show lock contention stat by address

-o::
--lock-owner::
	Show lock contention stat by owners. This option can be combined with -t,
	which shows owner's per thread lock stats, or -v, which shows owner's
	stacktrace. Requires --use-bpf.

-Y::
--type-filter=<value>::
	Show lock contention only for given lock types (comma separated list).
	Available values are:
	  semaphore, spinlock, rwlock, rwlock:R, rwlock:W, rwsem, rwsem:R, rwsem:W,
	  rtmutex, rwlock-rt, rwlock-rt:R, rwlock-rt:W, percpu-rwmem, pcpu-sem,
	  pcpu-sem:R, pcpu-sem:W, mutex

	Note that RW-variant of locks have :R and :W suffix.  Names without the
	suffix are shortcuts for the both variants.  Ex) rwsem = rwsem:R + rwsem:W.

-L::
--lock-filter=<value>::
	Show lock contention only for given lock addresses or names (comma separated list).

-S::
--callstack-filter=<value>::
	Show lock contention only if the callstack contains the given string.
	Note that it matches the substring so 'rq' would match both 'raw_spin_rq_lock'
	and 'irq_enter_rcu'.

-x::
--field-separator=<SEP>::
	Show results using a CSV-style output to make it easy to import directly
	into spreadsheets. Columns are separated by the string specified in SEP.

--lock-cgroup::
	Show lock contention stat by cgroup.  Requires --use-bpf.

-G::
--cgroup-filter=<value>::
	Show lock contention only in the given cgroups (comma separated list).

-J::
--inject-delay=<time@function>::
	Add delays to the given lock.  It's added to the contention-end part so
	that the (new) owner of the lock will be delayed.  But by slowing down
	the owner, the waiters will also be delayed as well.  This is working
	only with -b/--use-bpf.

	The 'time' is specified in nsec but it can have a unit suffix.  Available
	units are "ms", "us" and "ns".  Currently it accepts up to 10ms of delays
	for safety reasons.

	Note that it will busy-wait after it gets the lock. Delaying locks can
	have significant consequences including potential kernel crashes.  Please
	use it at your own risk.


SEE ALSO
--------
linkperf:perf[1]
