VMSTAT(8)						    BSD System Manager's Manual 						 VMSTAT(8)

NAME

     vmstat -- report virtual memory statistics

SYNOPSIS

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

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 currently running kernel via the sysctl(3) interface.	Otherwise, infor-
     mation 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.

     -h      Changes memory columns into more easily human readable form.  The default if standard output is a terminal device.

     -H      Changes memory columns into straight numbers.  The default if standard output is not a terminal device (such as a script).

     -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 system
	     has booted from.

     -m      Report on the usage of kernel dynamic memory allocated using malloc(9) by type.

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

     -P      Report per-cpu system/user/idle cpu statistics.

     -p      Specify which types of devices to display.  There are three different 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
		     scanner	Scanner devices
		     optical	Optical Memory devices
		     changer	Medium Changer devices
		     comm	Communication devices
		     array	Storage Array devices
		     enclosure	Enclosure Services devices
		     floppy	Floppy 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 commas.

	     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 two devices, or the maximum number of devices specified by the user.

     -s      Display the contents of the sum structure, giving the total number 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.  The vmstat command will
	     accept and honor a non-integer number of seconds.

     -z      Report on memory used by the kernel zone allocator, uma(9), by zone.

     The wait and count arguments may be given after their respective flags at any point on the command line before the disks argument(s), or
     without their flags, as the final argument(s).  The latter form is accepted for backwards compatibility, but it is preferred to use the forms
     with -w and -c to avoid ambiguity.

     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).  Typically paging will be split across the available drives.	The header
	     of the field is the first two characters of the disk name and the unit number.  If more than two disk drives are configured in the
	     system, vmstat displays only the first two drives, unless the user specifies the -n argument to increase the number of drives dis-
	     played.  This will probably cause the display to exceed 80 columns, however.  To force vmstat to display specific drives, their names
	     may be supplied on the command line.  The vmstat utility defaults to show disks first, and then various other random devices in the
	     system to add up to two devices, if there are that many devices in the system.  If devices are specified 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 pat-
	     tern, 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 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

FILES

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

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

SEE ALSO

     fstat(1), netstat(1), nfsstat(1), ps(1), systat(1), libmemstat(3), gstat(8), iostat(8), pstat(8), sysctl(8), malloc(9), uma(9)

     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.

BSD
								  August 8, 2014							       BSD