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Power 6/32 Unix version 1.21

.TH VMSTAT 1 "26 April 1981"
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.UC 4
.SH NAME
vmstat \- report virtual memory statistics
.SH SYNOPSIS
.B vmstat
[
.B \-01rfs
]
[ interval [ count ] ]
.SH DESCRIPTION
.I Vmstat
delves into the system and normally reports certain statistics kept about
process, virtual memory, disk, trap and cpu activity.
.PP
The POWER 6/32 can support up to 32 disk drives.  
.I Vmstat
can only display 16 drives at one time.
The 
.B \-0
argument will display the first 16 mounted disk drives, and the
.B \-1
argument will display the second 16 mounted disk drives. 
These options take effect only if the system has more
than 16 mounted drives.
The
.B \-0
argument is the default.  
Any time during the display, you can type in
a 0, 1 or r to change the display.
.PP
The
.B \-r
argument, switches between displaying the first and second
16 mounted disk drives, i.e., 
it switches back and forth between the 0 and 1 options.
This option takes effect only if the system has more
than 16 mounted drives.
The duration for each set of drives will be [interval]/2.
.PP
If given an
.B \-f
argument, 
.I vmstat
reports on the number of
.I forks
and
.I vforks
since system startup and the number 
of pages of virtual memory involved in each
kind of fork.
If given a
.B \-s
argument, it instead prints the contents
of the
.I sum
structure, giving the total number 
of several kinds of paging related
events which have occurred since boot.
.PP
If none of these options are given,
.I vmstat
will report in the first line a summary 
of the virtual memory activity 
since the system has been booted.
If
.I interval
is specified, then successive lines 
are summaries over the last
.I interval
seconds.
``vmstat 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.  Running the output for a while will make it
apparent which statistics are recomputed every second.
If a
.I count
is given, the statistics are repeated
.I count
times.
The format fields are:
.PP
Procs: information about numbers of processes in various states.
.s1
.t1
.nf
r	in run queue
b	blocked for resources (i/o, paging, etc.)
w	runnable or short sleeper (< 20 secs) but swapped
.fi
.s1
Memory: information about the usage of 
virtual and real memory.  Virtual pages 
are considered active if they belong to processes which
are running or have run in the last 20 seconds.
A ``page'' here is 1024 bytes.
.s1
.t1
.nf
avm	active virtual pages
fre	size of the free list
.fi
.s1
Page: information about page faults and paging activity.
These are averaged each five seconds, 
and given in units per second.
.s1
.t1
.nf
re	page reclaims less the free lists in the swap 
	devices and the file system
at	pages of free lists in the swap devices and the file system
pi	pages paged in
po	pages paged out
fr	pages freed per second
de	anticipated short term memory shortfall
sr	pages scanned by clock algorithm, per-second
.fi
.s1
x/f/s: Disk operations per second (this 
field is system dependent).
Typically paging will be split across 
several of the available drives.
The number under each of these is the unit number.
.s1
Faults: trap/interrupt rate averages per second over last 5 seconds.
.s1
.t1
.nf
in	(non clock) device interrupts per second
sy	system calls per second
cs	cpu context switch rate (switches/sec)
.fi
.s1
Cpu: breakdown of percentage usage of CPU time
.s1
.nf
us	user time for normal and low priority processes
sy	system time
id	cpu idle
.SH FILES
/dev/kmem, /vmunix
.SH SEE ALSO
The sections starting with ``Interpreting system activity'' in
.IR "Installing and Operating 4.2bsd" .
.SH AUTHORS
William Joy and Ozalp Babaoglu
.SH BUGS
There should be a screen oriented program which combines
.I vmstat
and
.IR ps (1)
in real time
as well as reporting on other system activity.

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