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

     vmstat -- report virtual memory statistics

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

     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 de-
	     fault 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.  De-
	     fault if standard output is a terminal device.

     -H	     Changes memory columns into straight numbers.  Default if stan-
	     dard 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

     -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 allocated using
	     malloc(9) by type.

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

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

     -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
		     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

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

		     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-

	     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 spec-
	     ified 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 in-
	     terval is specified, the default is 1 second.

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

     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 av-
	     eraged 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 displayed.	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 ran-
	     dom 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 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-
	     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

     /boot/kernel/kernel  default kernel namelist
     /dev/kmem		  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 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-

     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 statis-
     tics every	second.

     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.

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

BSD			       October 21, 2006				   BSD


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