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

vmstatreport virtual memory statistics

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

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

The options are as follows:

Formatted numbers use a brief format which some may find more readable with looped output.
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.
Report on the number of interrupts taken by each device since system startup.
Extract values associated with the name list from the specified core instead of the default /dev/kmem.
Extract the name list from the specified system instead of the default /boot/kernel.
Report on the usage of kernel dynamic memory listed first by size of allocation and then by type of usage.
Change the maximum number of disks to display from the default of 2.
Report the usage of kernel object cache. It only works on the running system.
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 three devices, or the maximum number of devices specified by the user.

Display the contents of the structure, giving the total number of several kinds of paging related events which have occurred since system startup.
Output unformatted numeric values, suitable for field extraction and numeric sorting. Columnar output will not be nicely aligned.
If specified together with -i, include IRQ numbers and IRQ target CPU numbers before device names.
Pause wait seconds between each display. If no repeat wait interval is specified, the default is 1 second.
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.

fre
Approximate free and easily-freeable memory.
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
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 three disk drives are configured in the system, vmstat displays only the first three 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. vmstat 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 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.

int
device interrupts per interval (including clock interrupts)
sys
system calls per interval
ctx
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
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 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 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 statistics every second.

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.

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

May 30, 2013 DragonFly-5.6.1