vmstat —
report virtual memory statistics
  
    | vmstat | [ -CefHiLlmstUvW] [-ccount] [-hhashname] [-Mcore] [-Nsystem] [-ndiskcount] [-uhistname] [-wwait] [disks] | 
vmstat reports certain kernel statistics kept about
  process, virtual memory, disk, trap, and CPU activity. If
  vmstat is invoked without any options, it displays the
  summary of statistics since boot and exits. This is also referred to as the
  first line of vmstat.
The options are as follows:
  - -C
- Report on kernel memory caches. Combine with the
      -moption to see information about memory pools
      that back the caches.
- -ccount
- Repeat the display count times. The first display is
      for the time since a reboot and each subsequent report is for the time
      period since the last display. If no wait interval
      is specified, the default is 1 second.
- -e
- Report the values of system event counters.
- -f
- Report fork statistics.
- -H
- Report all hash table statistics.
- -hhashname
- Report hash table statistics for hashname.
- -i
- Report the values of system interrupt counters.
- -L
- List all the hashes supported for -hand-H.
- -l
- List the UVM histories being maintained by the kernel.
- -Mcore
- Extract values associated with the name list from the specified core
      instead of the default /dev/mem.
- -m
- Report on the list of the kernel memory pools and their usage.
- -Nsystem
- Extract the name list from the specified system instead of the default
      /netbsd.
- -ndiskcount
- Display up to diskcount disks in the standard
      output, instead of the default 2.
- -s
- Display the contents of the uvmexpstructure. This
      contains various paging event and memory status counters.
- -t
- Display the contents of the vmtotalstructure.
      This includes information about processes and virtual memory.The process part shows the number of processes in the
        following states: 
      - ru
- on the run queue
- dw
- in disk I/O wait
- pw
- waiting for paging
- sl
- sleeping
 The virtual memory section shows: 
      - total-v
- Total virtual memory
- active-v
- Active virtual memory in use
- active-r
- Active real memory in use
- vm-sh
- Shared virtual memory
- avm-sh
- Active shared virtual memory
- rm-sh
- Shared real memory
- arm-sh
- Active shared real memory
- free
- Free memory
 All memory values are shown in number of pages. 
- -U
- Dump all UVM histories.
- -uhistname
- Dump the specified UVM history.
- -v
- Print more verbose information. When used with the
      -i,-e, or-moptions prints out all counters, not just those
      with non-zero values.
- -W
- Print more verbose information about kernel memory pools.
- -wwait
- Pause wait seconds between each display. If no
      repeat count is specified, the default is infinity.
      The vmstatcommand will accept and honor a
      negative number of wait seconds.
By default, vmstat displays the following
    information:
  - procs
- Information about the numbers of processes in various states.
    
    
      - r
- in run queue
- b
- blocked for resources (i/o, paging, etc.)
 
- memory
- Information about the usage of virtual and real memory. Virtual pages
      (reported in units of 1024 bytes) are considered active if they belong to
      processes which are running or have run in the last 20 seconds.
    
    
      - avm
- active virtual pages
- fre
- size of the free list
 
- page
- Information about page faults and paging activity. These are averaged
      every five seconds, and given in units per second.
    
    
      - flt
- total page faults
- re
- page reclaims (simulating reference bits)
- pi
- pages paged in
- po
- pages paged out
- fr
- pages freed per second
- sr
- pages scanned by clock algorithm, per-second
 
- disks
- Disk transfers per second. Typically paging will be split across the
      available drives. The header of the field is the first character of the
      disk name and the unit number. If more than four disk drives are
      configured in the system, vmstatdisplays only the
      first four drives. To forcevmstatto display
      specific drives, their names may be supplied on the command line.
- faults
- Trap/interrupt rate averages per second over last 5 seconds.
    
    
      - in
- device interrupts per interval (including clock interrupts)
- sy
- system calls per interval
- cs
- CPU context switch rate (switches/interval)
 
- cpu
- Breakdown of percentage usage of CPU time.
    
    
      - us
- user time for normal and low priority processes
- sy
- system time
- id
- CPU idle
 
  - /netbsd
- default kernel namelist
- /dev/mem
- default memory file
The command “vmstat -w 5” will print what
  the system is doing every five seconds; this is a good choice of printing
  interval since this is how often some of the statistics are sampled in the
  system. Others vary every second and running the output for a while will make
  it apparent which are recomputed every second.
The -c, -n, and
  -w options are only available with the default output.
The -l, -U, and
    -u options are useful only if the system was
    compiled with support for UVM history.