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]
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