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vmstat(8)

NAME

     vmstat -- report virtual memory statistics

SYNOPSIS

     vmstat [-afimsz] [-c count] [-M core [-N system]] [-w wait] [-n devs] [-p
	    type,if,pass] [disks]

DESCRIPTION

     The vmstat utility reports certain kernel statistics kept about process,
     virtual memory, disk, trap and cpu activity.

     If the -M option is not specified, information is obtained from the cur-
     rently running kernel via the sysctl(3) interface.  Otherwise, informa-
     tion is read from the specified core file, using the name list from the
     specified kernel image (or from the default image).

     The options are as follows:

     -a      When used with -i, include statistics about interrupts that have
	     never been generated.

     -c      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 repeat count is specified,
	     and -w is specified, the default is infinity, otherwise the
	     default is one.

     -f      Report on the number fork(2), vfork(2) and rfork(2) system calls
	     since system startup, and the number of pages of virtual memory
	     involved in each.

     -i      Report on the number of interrupts taken by each device since
	     system startup.

     -M      Extract values associated with the name list from the specified
	     core.

     -N      If -M is also specified, extract the name list from the specified
	     system instead of the default, which is the kernel image the sys-
	     tem has booted from.

     -m      Report on the usage of kernel dynamic memory listed first by size
	     of allocation and then by type of usage.

     -n      Change the maximum number of disks to display from the default of
	     2.

     -p      Specify which types of devices to display.  There are three dif-
	     ferent categories of devices:

	     device type:
		     da 	Direct Access devices
		     sa 	Sequential Access devices
		     printer	Printers
		     proc	Processor devices
		     worm	Write Once Read Multiple devices
		     cd 	CD devices

	     interface:
		     IDE	Integrated Drive Electronics devices
		     SCSI	Small Computer System Interface devices
		     other	Any other device interface

	     passthrough:
		     pass	Passthrough devices

	     The user must specify at least one device type, and may specify
	     at most one device type from each category.  Multiple device
	     types in a single device type statement must be separated by com-
	     mas.

	     Any number of -p arguments may be specified on the command line.
	     All -p arguments are ORed together to form a matching expression
	     against which all devices in the system are compared.  Any device
	     that fully matches any -p argument will be included in the vmstat
	     output, up to three devices, or the maximum number of devices
	     specified by the user.

     -s      Display the contents of the sum structure, giving the total num-
	     ber of several kinds of paging related events which have occurred
	     since system startup.

     -w      Pause wait seconds between each display.  If no repeat wait
	     interval is specified, the default is 1 second.

     -z      Report on memory used by the kernel zone allocator, by zone.  The
	     information shown is the same as that returned by the vm.zone
	     sysctl variable.

     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.)
	     w	     runnable or short sleeper (< 20 secs) but swapped

     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 each five seconds, and given in units per second.

	     flt     total number of 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 operations per second (this field is system dependent).
	     vmstat utility defaults to show disks first, and then various
	     other random devices in the system to add up to three devices, if
	     there are that many devices in the system.  If devices are speci-
	     fied on the command line, or if a device type matching pattern is
	     specified (see above), vmstat will only display the given devices
	     or the devices matching the pattern, and will not randomly select
	     other devices in the system.

     faults  Trap/interrupt rate averages per second over last 5 seconds.

	     in      device interrupts per interval (including clock inter-
		     rupts)
	     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

EXAMPLES

     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 statis-
     tics are sampled in the system.  Others vary every second and running the
     output for a while will make it apparent which are recomputed every sec-
     ond.

     The command:
	   vmstat -p da -p cd -w 1
     will tell vmstat to select the first three direct access or CDROM devices
     and display statistics on those devices, as well as other systems statis-
     tics every second.

FILES

     /boot/kernel/kernel  default kernel namelist
     /dev/kmem		  default memory file

SEE ALSO

     fstat(1), netstat(1), nfsstat(1), ps(1), systat(1), iostat(8), pstat(8),
     sysctl(8)

     The sections starting with ``Interpreting system activity'' in Installing
     and Operating 4.3BSD.

BUGS

     The -c and -w options are only available with the default output.

FreeBSD 5.4		       December 10, 2003		   FreeBSD 5.4

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