PERF-LOCK(1)

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 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[1]>
    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

perf(1)

NOTES

1.  time@function
    mailto:time@function