xref: /freebsd/usr.bin/vmstat/vmstat.8 (revision bdcbfde31e8e9b343f113a1956384bdf30d1ed62)

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.Dd June 21, 2021
.Dt VMSTAT 8
.Os
.Sh NAME
.Nm vmstat
.Nd report virtual memory statistics
.Sh SYNOPSIS
.Nm
.\" .Op Fl fimst
.Op Fl -libxo
.Op Fl afHhimoPsz
.Op Fl M Ar core Op Fl N Ar system
.Op Fl c Ar count
.Op Fl n Ar devs
.Oo
.Fl p
.Sm off
.Ar type , if , pass
.Sm on
.Oc
.Op Fl w Ar wait
.Op Ar disks ...
.Op wait Op count
.Sh DESCRIPTION
The
.Nm
utility reports certain kernel statistics kept about process, virtual memory,
disk, trap and cpu activity.
.Pp
If the
.Fl M
option is not specified, information is obtained from
the currently running kernel via the
.Xr sysctl 3
interface.
Otherwise, information is read from the specified core file,
using the name list from the specified kernel image (or from
the default image).
.Pp
The options are as follows:
.Bl -tag -width indent
.It Fl -libxo
Generate output via
.Xr libxo 3
in a selection of different human and machine readable formats.
See
.Xr xo_parse_args 3
for details on command line arguments.
.It Fl a
When used with
.Fl i ,
include statistics about interrupts that have never been generated.
.It Fl c
Repeat the display
.Ar 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
.Ar count
is specified, and
.Fl w
is specified, the default is infinity, otherwise the default is one.
.It Fl f
Report on the number
.Xr fork 2 ,
.Xr vfork 2
and
.Xr rfork 2
system calls since system startup, and the number of pages of virtual memory
involved in each.
.It Fl h
Changes memory columns into more easily human readable form.
The default if
standard output is a terminal device.
.It Fl H
Changes memory columns into straight numbers.
The default if standard output
is not a terminal device (such as a script).
.It Fl i
Report on the number of interrupts taken by each device since system
startup.
.It Fl M
Extract values associated with the name list from the specified
.Ar core .
.It Fl N
If
.Fl M
is also specified,
extract the name list from the specified
.Ar system
instead of the default,
which is the kernel image the system has booted from.
.It Fl m
Report on the usage of kernel dynamic memory allocated using
.Xr malloc 9
by type.
.It Fl n
Change the maximum number of disks to display from the default of 2.
.It Fl o
Display a list of virtual memory objects in the system and the resident
memory used by each object.
.It Fl P
Report per-cpu system/user/idle cpu statistics.
.It Fl p
Specify which types of devices to display.
There are three different
categories of devices:
.Pp
.Bl -tag -width indent -compact
.It device type:
.Bl -tag -width 9n -compact
.It da
Direct Access devices
.It sa
Sequential Access devices
.It printer
Printers
.It proc
Processor devices
.It worm
Write Once Read Multiple devices
.It cd
CD devices
.It scanner
Scanner devices
.It optical
Optical Memory devices
.It changer
Medium Changer devices
.It comm
Communication devices
.It array
Storage Array devices
.It enclosure
Enclosure Services devices
.It floppy
Floppy devices
.El
.Pp
.It interface:
.Bl -tag -width 9n -compact
.It IDE
Integrated Drive Electronics devices
.It SCSI
Small Computer System Interface devices
.It NVME
NVM Express Interface devices
.It other
Any other device interface
.El
.Pp
.It passthrough:
.Bl -tag -width 9n -compact
.It pass
Passthrough devices
.El
.El
.Pp
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.
.Pp
Any number of
.Fl p
arguments may be specified on the command line.
All
.Fl 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
.Fl p
argument will be included in the
.Nm
output, up to two devices, or the maximum number of devices specified
by the user.
.It Fl s
Display the contents of the
.Em sum
structure, giving the total number of several kinds of paging related
events which have occurred since system startup.
.It Fl w
Pause
.Ar wait
seconds between each display.
If no repeat
.Ar wait
interval is specified, the default is 1 second.
The
.Nm
command will accept and honor a non-integer number of seconds.
.It Fl z
Report on memory used by the kernel zone allocator,
.Xr uma 9 ,
by zone.
.El
.Pp
The
.Ar wait
and
.Ar count
arguments may be given after their respective flags at any point
on the command line before the
.Ar 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
.Fl w
and
.Fl c
to avoid ambiguity.
.Pp
By default,
.Nm
displays the following information:
.Bl -tag -width indent
.It procs
Information about the number of threads in various states:
.Pp
.Bl -tag -width indent -compact
.It r
running or in run queue
.It b
blocked for resources (i/o, paging, etc.)
.It w
swapped out
.El
.It memory
Information about the usage of virtual and real memory.
.Pp
Mapped virtual memory is a sum of all of the virtual pages belonging
to mapped virtual memory objects.
Note that the entire memory object's size is considered mapped even if
only a subset of the object's pages are currently mapped.
This statistic is not related to the active page queue which is used to track
real memory.
.Pp
.Bl -tag -width indent -compact
.It avm
mapped virtual memory
.Po previously called active in
.Nm
output
.Pc
.It fre
size of the free list
.El
.It page
Information about page faults and paging activity.
These are given in units per second.
.Pp
.Bl -tag -width indent -compact
.It flt
total number of page faults
.It re
pages reactivated (found in laundry or inactive queues)
.\" .It at
.\" pages attached (found in free list)
.It pi
pages paged in
.It po
pages paged out
.It fr
pages freed
.\" .It de
.\" anticipated short term memory shortfall
.It sr
pages scanned by page daemon
.El
.It 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,
.Nm
displays only the first two drives, unless the user specifies the
.Fl n
argument to increase the number of drives displayed.
This will probably
cause the display to exceed 80 columns, however.
To force
.Nm
to display specific drives, their names may be supplied on the command line.
The
.Nm
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),
.Nm
will only display the given devices or the devices matching the pattern,
and will not randomly select other devices in the system.
.It faults
Trap/interrupt rates per second.
.Pp
.Bl -tag -width indent -compact
.It in
device interrupts (including clock interrupts)
.It sy
system calls
.It cs
cpu context switches
.El
.It cpu
Breakdown of percentage usage of CPU time.
.Pp
.Bl -tag -width indent -compact
.It us
user time for normal and low priority processes
.It sy
system and interrupt time
.It id
cpu idle
.El
.El
.Sh FILES
.Bl -tag -width /boot/kernel/kernel -compact
.It Pa /boot/kernel/kernel
default kernel namelist
.It Pa /dev/kmem
default memory file
.El
.Sh EXAMPLES
The command:
.Dl vmstat -w 5
will print what the system is doing every five
seconds.
.Pp
The command:
.Dl 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.
.Sh SEE ALSO
.Xr fstat 1 ,
.Xr netstat 1 ,
.Xr nfsstat 1 ,
.Xr ps 1 ,
.Xr systat 1 ,
.Xr libmemstat 3 ,
.Xr libxo 3 ,
.Xr xo_parse_args 3 ,
.Xr gstat 8 ,
.Xr iostat 8 ,
.Xr pstat 8 ,
.Xr sysctl 8 ,
.Xr malloc 9 ,
.Xr uma 9
.Pp
The sections starting with ``Interpreting system activity'' in
.%T "Installing and Operating 4.3BSD" .
.Sh HISTORY
The
.Nm
utility first appeared in
.Bx 3 .
.Sh BUGS
The
.Fl c
and
.Fl w
options are only available with the default output.