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.\"	@(#)vmstat.8	8.1 (Berkeley) 6/6/93
.\"
.Dd December 5, 2018
.Dt VMSTAT 1
.Os
.Sh NAME
.Nm vmstat
.Nd report virtual memory statistics
.Sh SYNOPSIS
.Nm
.Op Fl CefHiLlmstUvW
.Op Fl c Ar count
.Op Fl h Ar hashname
.Op Fl M Ar core
.Op Fl N Ar system
.Op Fl u Ar histname
.Op Fl w Ar wait
.Op Ar disks
.Sh DESCRIPTION
.Nm
reports certain kernel statistics kept about process, virtual memory,
disk, trap, and CPU activity.
.Pp
The options are as follows:
.Bl -tag -width xxxhistname
.It Fl C
Report on kernel memory caches.
Combine with the
.Fl m
option to see information about memory pools that back the caches.
.It Fl c Ar count
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
.Ar wait
interval is specified, the default is 1 second.
.It Fl e
Report the values of system event counters.
.It Fl f
Report fork statistics.
.It Fl H
Report all hash table statistics.
.It Fl h Ar hashname
Report hash table statistics for
.Ar hashname .
.It Fl i
Report the values of system interrupt counters.
.It Fl L
List all the hashes supported for
.Fl h
and
.Fl H .
.It Fl l
List the UVM histories being maintained by the kernel.
.It Fl M Ar core
Extract values associated with the name list from the specified core
instead of the default
.Pa /dev/mem .
.It Fl m
Report on the usage of kernel dynamic memory listed first by size of
allocation and then by type of usage,
followed by a list of the kernel memory pools and their usage.
.It Fl N Ar system
Extract the name list from the specified system instead of the default
.Pa /netbsd .
.It Fl s
Display the contents of the
.Dv uvmexp
structure.
This contains various paging event and memory status counters.
.It Fl t
Display the contents of the
.Dv vmtotal
structure.
This includes information about processes and virtual memory.
.Pp
The process part shows the number of processes in the following states:
.Pp
.Bl -tag -width abc -compact
.It ru
on the run queue
.It dw
in disk I/O wait
.It pw
waiting for paging
.It sl
sleeping
.El
.Pp
The virtual memory section shows:
.Pp
.Bl -tag -width abcdefgh -compact
.It total-v
Total virtual memory
.It active-v
Active virtual memory in use
.It active-r
Active real memory in use
.It vm-sh
Shared virtual memory
.It avm-sh
Active shared virtual memory
.It rm-sh
Shared real memory
.It arm-sh
Active shared real memory
.It free
Free memory
.El
.Pp
All memory values are shown in number of pages.
.It Fl U
Dump all UVM histories.
.It Fl u Ar histname
Dump the specified UVM history.
.It Fl v
Print more verbose information.
When used with the
.Fl i ,
.Fl e ,
or
.Fl m
options prints out all counters, not just those with non-zero values.
.It Fl W
Print more verbose information about kernel memory pools.
.It Fl w Ar wait
Pause
.Ar wait
seconds between each display.
If no repeat
.Ar count
is specified, the default is infinity.
The
.Nm
command will accept and honor a negative number of
.Ar wait
seconds.
.El
.Pp
By default,
.Nm
displays the following information:
.Bl -tag -width memory
.It procs
Information about the numbers of processes in various states.
.Pp
.Bl -tag -width abcd -compact
.It r
in run queue
.It b
blocked for resources (i/o, paging, etc.)
.El
.It 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.
.Pp
.Bl -tag -width abcd -compact
.It avm
active virtual pages
.It fre
size of the free list
.El
.It page
Information about page faults and paging activity.
These are averaged every five seconds, and given in units per second.
.Pp
.Bl -tag -width abcd -compact
.It flt
total page faults
.It re
page reclaims (simulating reference bits)
.It pi
pages paged in
.It po
pages paged out
.It fr
pages freed per second
.It sr
pages scanned by clock algorithm, per-second
.El
.It disks
Disk transfers per second.
Typically paging will be split across the available drives.
The header of the field is the first character of the disk name and
the unit number.
If more than four disk drives are configured in the system,
.Nm
displays only the first four drives.
To force
.Nm
to display specific drives, their names may be supplied on the command line.
.It faults
Trap/interrupt rate averages per second over last 5 seconds.
.Pp
.Bl -tag -width abcd -compact
.It in
device interrupts per interval (including clock interrupts)
.It sy
system calls per interval
.It cs
CPU context switch rate (switches/interval)
.El
.It cpu
Breakdown of percentage usage of CPU time.
.Pp
.Bl -tag -width abcd -compact
.It us
user time for normal and low priority processes
.It sy
system time
.It id
CPU idle
.El
.El
.Sh FILES
.Bl -tag -width eeenymeeny -compact
.It Pa /netbsd
default kernel namelist
.It Pa /dev/mem
default memory file
.El
.Sh EXAMPLES
The command
.Dq Li 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.
.Sh SEE ALSO
.Xr fstat 1 ,
.Xr netstat 1 ,
.Xr nfsstat 1 ,
.Xr ps 1 ,
.Xr systat 1 ,
.Xr iostat 8 ,
.Xr pstat 8 ,
.Xr kernhist 9
.Pp
The sections starting with
.Dq Interpreting system activity
in
.%T Installing and Operating 4.3BSD .
.Sh BUGS
The
.Fl c
and
.Fl w
options are only available with the default output.
.Pp
The
.Fl l ,
.Fl U ,
and
.Fl u
options are useful only if the system was compiled with support for UVM
history.