PERF-LOCK(1)

📦
version 7.3.1 · 41 versions
, in arch rolling

💅 PERF-LOCK — okay bestie, let's talk about perf-lock(1) 🎀

So this is the perf lock page from the perf manual — like, the whole command family for snooping on your kernel's lock behaviour. Grab a snack, we're analyzing lock events fr fr. 🦋

✨ NAME ✨

perf-lock — Analyze lock events 👑

🌸 SYNOPSIS 🌸

perf lock {record|report|script|info|contention}

🫶 DESCRIPTION 🫶

Okay so, with this perf lock command you can analyze, like, various lock behaviours and statistics. It's giving observability main character energy. 💅

  • 'perf lock record <command>' records lock events between start and end of <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 ⭐

These ones are the shared besties, they work across the subcommands:

  • -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). Tell me everything bestie.
  • -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. 💀 (literally the vibe)
  • --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. 💀😭 Like, for real, be careful with this one.

🌈 SEE ALSO 🌈

perf(1) — go read that one next, iykyk 💜

🎀 NOTES 🎀

  1. time@function mailto:time@function

And that's the whole page, bestie — you ate that. 💅✨

Little sign-off from the manual itself: this page is perf, dated 10/31/2026, and it's PERF-LOCK(1) — go forth and lock-analyze responsibly 🫶🌸

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