vmstat(1) vmstat(1)
NAME [Toc] [Back]
vmstat - report virtual memory statistics
SYNOPSIS [Toc] [Back]
vmstat [-dnS] [interval [count]]
vmstat -f | -s | -z
DESCRIPTION [Toc] [Back]
The vmstat command reports certain statistics kept about process,
virtual memory, trap, and CPU activity. It also can clear the
accumulators in the kernel sum structure.
Options [Toc] [Back]
vmstat recognizes the following options:
-d Report disk transfer information as a separate section,
in the form of transfers per second.
-n Provide an output format that is more easily viewed on
an 80-column display device. This format separates the
default output into two groups: virtual memory
information and CPU data. Each group is displayed as a
separate line of output. On multiprocessor systems,
this display format also provides CPU utilization on a
per CPU basis for the active processors.
-S Report the number of processes swapped in and out (si
and so) instead of page reclaims and address
translation faults (re and at).
interval Display successive lines which are summaries over the
last interval seconds. The first line reported is for
the time since a reboot and each subsequent line is for
the last interval only. If interval is zero, the
output is displayed once only. If the -d option is
specified, the column headers are repeated. If -d is
omitted, the column headers are not repeated.
The command vmstat 5 prints 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.
count Repeat the summary statistics count times. If count is
omitted or zero, the output is repeated until an
interrupt or quit signal is received. From the
terminal, these are commonly ^C and ^\, respectively
(see stty(1)).
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vmstat(1) vmstat(1)
-f Report on the number of forks and the number of pages
of virtual memory involved since boot-up.
-s Print the total number of several kinds of pagingrelated
events from the kernel sum structure that have
occurred since boot-up or since vmstat was last
executed with the -z option.
-z Clear all accumulators in the kernel sum structure.
This option is restricted to the super user.
If none of these options is given, vmstat displays a one-line summary
of the virtual memory activity since boot-up or since the -z option
was last executed.
Column Descriptions [Toc] [Back]
The column headings and the meaning of each column are:
procs Information about 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 are considered active if they
belong to processes that are running or have run in
the last 20 seconds.
avm Active virtual pages
free Size of the free list
page Information about page faults and paging activity.
These are averaged each five seconds, and given in
units per second.
re Page reclaims (without -S)
at Address translation faults (without -S)
si Processes swapped in (with -S)
so Processes swapped out (with -S)
pi Pages paged in
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vmstat(1) vmstat(1)
po Pages paged out
fr Pages freed per second
de Anticipated short term memory shortfall
sr Pages scanned by clock algorithm, per
second
faults Trap/interrupt rate averages per second over last 5
seconds.
in Device interrupts per second (nonclock)
sy System calls per second
cs CPU context switch rate (switches/sec)
cpu Breakdown of percentage usage of CPU time for the
active processors
us User time for normal and low priority
processes
sy System time
id CPU idle
EXAMPLES [Toc] [Back]
The following examples show the output for various command options.
For formatting purposes, some leading blanks have been deleted.
1. Display the default output.
vmstat
procs memory page
faults cpu
r b w avm free re at pi po fr de sr
in sy cs us sy id
0 0 0 1158 511 0 0 0 0 0 0 0
111 18 7 0 0 100
2. Add the disk tranfer information to the default output.
vmstat -d
procs memory page
faults cpu
r b w avm free re at pi po fr de sr
in sy cs us sy id
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vmstat(1) vmstat(1)
0 0 0 1158 511 0 0 0 0 0 0 0
111 18 7 0 0 100
Disk Transfers [Toc] [Back]
device xfer/sec
c0t6d0 0
c0t1d0 0
c0t3d0 0
c0t5d0 0
3. Display the default output in 80-column format.
vmstat -n
VM [Toc] [Back]
memory page faults
avm free re at pi po fr de sr in sy cs
1158 430 0 0 0 0 0 0 0 111 18 7
CPU
cpu procs
us sy id r b w
0 0 100 0 0 0
4. Replace the page reclaims and address translation faults with
process swapping in the default output.
vmstat -S
procs memory page
faults cpu
r b w avm free si so pi po fr de sr
in sy cs us sy id
0 0 0 1158 430 0 0 0 0 0 0 0
111 18 7 0 0 100
5. Display the default output twice at five-second intervals. Note
that the headers are not repeated.
vmstat 5 2
procs memory page
faults cpu
r b w avm free re at pi po fr de sr
in sy cs us sy id
0 0 0 1158 456 0 0 0 0 0 0 0
111 18 7 0 0 100
0 0 0 1221 436 5 0 5 0 0 0 0
108 65 18 0 1 99
6. Display the default output twice in 80-column format at fivesecond
intervals. Note that the headers are not repeated.
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vmstat(1) vmstat(1)
vmstat -n 5 2
VM [Toc] [Back]
memory page faults
avm free re at pi po fr de sr in sy cs
1221 436 0 0 0 0 0 0 0 111 18 7
CPU
cpu procs
us sy id r b w
0 0 100 0 0 0
1221 435 2 0 2 0 0 0 0 109 35 17
0 1 99 0 0 0
7. Display the default output and disk transfers twice in 80-column
format at five-second intervals. Note that the headers are
repeated.
vmstat -dn 5 2
VM [Toc] [Back]
memory page faults
avm free re at pi po fr de sr in sy cs
1221 435 0 0 0 0 0 0 0 111 18 7
CPU
cpu procs
us sy id r b w
0 0 100 0 0 0
Disk Transfers [Toc] [Back]
device xfer/sec
c0t6d0 0
c0t1d0 0
c0t3d0 0
c0t5d0 0
VM [Toc] [Back]
memory page faults
avm free re at pi po fr de sr in sy cs
1219 425 0 0 0 0 0 0 0 111 54 15
CPU
cpu procs
us sy id r b w
1 8 92 0 0 0
Disk Transfers [Toc] [Back]
device xfer/sec
c0t6d0 0
c0t1d0 0
c0t3d0 0
c0t5d0 0
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vmstat(1) vmstat(1)
8. Display the number of forks and pages of virtual memory since
boot-up.
vmstat -f
24558 forks, 1471595 pages, average= 59.92
9. Display the counts of paging-related events.
vmstat -s
0 swap ins
0 swap outs
0 pages swapped in
0 pages swapped out
1344563 total address trans. faults taken
542093 page ins
2185 page outs
602573 pages paged in
4346 pages paged out
482343 reclaims from free list
504621 total page reclaims
124 intransit blocking page faults
1460755 zero fill pages created
404137 zero fill page faults
366022 executable fill pages created
71578 executable fill page faults
0 swap text pages found in free list
162043 inode text pages found in free list
196 revolutions of the clock hand
45732 pages scanned for page out
4859 pages freed by the clock daemon
36680636 cpu context switches
1497746186 device interrupts
1835626 traps
87434493 system calls
WARNINGS [Toc] [Back]
Users of vmstat must not rely on the exact field widths and spacing of
its output, as these will vary depending on the system, the release of
HP-UX, and the data to be displayed.
AUTHOR [Toc] [Back]
vmstat was developed by the University of California, Berkeley and HP.
SEE ALSO [Toc] [Back]
iostat(1).
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