Manpages

NAME

perf-lock - Analyze lock events

SYNOPSIS

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 thread list in perf.data

-m, --map

dump 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. Implies --threads and
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, 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).

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