NAME
vmstat
—
report virtual memory
statistics
SYNOPSIS
vmstat |
[-imosuvz ] [-c
count] [-M
core] [-N
system] [-w
wait] [-n
devs] [-p
type,if,pass]
[disks] |
DESCRIPTION
Vmstat
reports certain kernel statistics kept about
process, virtual memory, disk, trap and cpu activity.
The options are as follows:
-b
- Formatted numbers use a brief format which some may find more readable with looped output.
-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. -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 instead of the default /dev/kmem.
-N
- Extract the name list from the specified system instead of the default /boot/kernel.
-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.
-o
- Report the usage of kernel object cache. It only works on the running system.
-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 thevmstat
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 number of several kinds of paging related events which have occurred since system startup.
-u
- Output unformatted numeric values, suitable for field extraction and numeric sorting. Columnar output will not be nicely aligned.
-v
- If specified together with
-i
, include IRQ numbers and IRQ target CPU numbers before device names. -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.
- 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 forcevmstat
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
FILES
- /boot/kernel
- default kernel namelist
- /dev/kmem
- default memory file
EXAMPLES
The command:
vmstat -w 5
The command:
vmstat -p da -p cd -w 1
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.