--- name: "perf-lock" section: "1" platform: "linux" package: "perf" version: "7.3.1-1" release: "Arch Linux 2026-11-01" platforms: ["linux"] url: "https://new.carta.tech/perf-lock" --- # perf-lock(1) Analyze lock events ## 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 ' records lock events between start and end . 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=\ Input file name. (default: perf.data unless stdin is a fifo) - \--output=\ 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=\ vmlinux pathname - \--kallsyms=\ kallsyms pathname ## REPORT OPTIONS - \-k, --key=\ Sorting key. Possible values: acquired (default), contended, avg\_wait, wait\_total, wait\_max, wait\_min. - \-F, --field=\ 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=\ 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=\ Sorting key. Possible values: contended, wait\_total (default), wait\_max, wait\_min, avg\_wait. - \-F, --field=\ 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=\ 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=\ Record events on existing process ID (comma separated list). - \--tid=\ Record events on existing thread ID (comma separated list). - \-M, --map-nr-entries=\ Maximum number of BPF map entries (default: 16384). This will be aligned to a power of 2. - \--max-stack=\ Maximum stack depth when collecting lock contention (default: 8). - \--stack-skip=\ Number of stack depth to skip when finding a lock caller (default: 3). - \-E, --entries=\ 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=\ 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=\ Show lock contention only for given lock addresses or names (comma separated list). - \-S, --callstack-filter=\ 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=\ 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=\ 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)](/perf/1.md) ## NOTES - 1\. time@function mailto:time@function