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\" @(#)vmstat.8 8.1 (Berkeley) 6/6/93
\"
Dd February 1, 2022
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 n Ar diskcount
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.
If
Nm
is invoked without any options, it displays the summary of statistics since
boot and exits.
This is also referred to as the first line of
Nm .
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 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 n Ar diskcount
Display up to
Ar diskcount
disks in the standard output, instead of the default 2.
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
Sh BUGS
The
Fl c ,
Fl n ,
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.