NAME

lockstat - display kernel locking statistics

SYNOPSIS

lockstat [-ceflMmpst] [-b nbuf] [-E event] [-F func] [-L lock] [-N nlist] [-o file] [-T type] command ...

DESCRIPTION

The lockstat command enables system wide tracing of kernel lock events, executes the specified command, and when finished reports statistics to the user.

Tracing may be ended early by sending SIGINT (Ctrl-C) to the process being executed by lockstat.

The lockstat pseudo-device driver must be present in the kernel, and the lockstat command may only be used by the root user.

The options are as follows:

-b nbuf
Adjust the number of trace buffers allocated by the kernel to nbuf.

-c
Report percentage of total events by count, and sort the output by number of events. The default is to key on event timings.

-E event
Limit tracing to one type of event. Use the -e option to list valid events.

-e
List valid event types for the -E option and exit.

-F func
Limit tracing to locking operations performed within the specified function. func must be the name of a valid function in the kernel.

-f
Trace only by calling functions; do not report on individual locks.

-L lock
Limit tracing to one lock. lock may either be the name of a lock object in the kernel, or a kernel virtual address.

-l
Trace only by lock; do not report on calling functions.

-M
Merge lock addresses within unique objects.

-m
Merge call sites within unique functions.

-N nlist
Extract symbol information from the nlist file.

-o file
Send output to the file named by file, instead of the standard output (the default).

-p
Show the average number of events and time spent per CPU. The default is to show the total values. May be used in conjunction with the -s option.

-s
Show the average number of events per second, and the average time spent per second. The default is to show the total values.

-T type
Limit tracing to one type of lock. Use the -t option to list valid lock types.

-t
List valid lock types for the -T option and exit.

FILES

/dev/lockstat
lockstat control device
/dev/ksyms
default namelist
/netbsd
namelist

EXAMPLES

# lockstat -T kernel_lock sleep 10
Elapsed time: 10.01 seconds.
        

-- Kernel lock spin

Total% Count Time/ms Lock Caller ------ ------- --------- ---------------------- ------------------------------ 100.00 74941 1545.54 kernel_lock <all> 43.54 28467 673.00 kernel_lock trap+71e 42.87 34466 662.51 kernel_lock syscall_plain+111 7.38 7565 114.14 kernel_lock uiomove+17a 1.92 1221 29.61 kernel_lock sleepq_block+20b 1.84 1759 28.40 kernel_lock trap+706 0.81 124 12.54 kernel_lock x86_softintlock+1a 0.64 587 9.87 kernel_lock pmap_load+2a6 0.52 214 8.10 kernel_lock intr_biglock_wrapper+1e 0.20 219 3.09 kernel_lock pmap_load+323 0.14 175 2.12 kernel_lock do_sys_wait+2d0 0.09 85 1.43 kernel_lock lwp_startup+66 0.04 49 0.64 kernel_lock sleepq_block+18c 0.01 10 0.12 kernel_lock lwp_userret+3c

DIAGNOSTICS

lockstat: incompatible lockstat interface version

The kernel device driver does not match the version of the lockstat command.

lockstat: overflowed available kernel trace buffers

Increase the number of buffers using the -b option.

lockstat: ioctl: Invalid argument

The number of trace buffers is outside the minimum and maximum bounds set by the kernel.

SEE ALSO

ps(1), systat(1), vmstat(1), iostat(8), pstat(8)

HISTORY

The lockstat command appeared in NetBSD4.0.