vmstat(1)vmstat(1)NAMEvmstat - report virtual memory statistics
SYNOPSIS
[interval [count]]
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DESCRIPTION
The command reports certain statistics kept about process, virtual mem‐
ory, trap, and CPU activity. It also can clear the accumulators in the
kernel structure.
Options
recognizes the following options:
Report disk transfer information as a separate section,
in the form of transfers per second.
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.
Report the number of processes swapped in and out
and instead of page reclaims and address translation
faults and
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 option is spec‐
ified, the column headers are repeated. If is omit‐
ted, the column headers are not repeated.
The command 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 termi‐
nal, these are commonly and respectively (see
stty(1)).
Report on the number of forks
and the number of pages of virtual memory involved
since boot-up.
Print the total number of several kinds of paging-related events
from the kernel structure that have occurred since
boot-up or since was last executed with the option.
Clear all accumulators in the kernel
structure. This option is restricted to the super
user.
If none of these options is given, displays a one-line summary of the
virtual memory activity since boot-up or since the option was last exe‐
cuted.
Column Descriptions
The column headings and the meaning of each column are:
Information about numbers of processes in various states.
In run queue
Blocked for resources (I/O, paging, etc.)
Runnable or short sleeper (< 20 secs) but
swapped
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.
Active virtual pages
Size of the free list
Information about page faults and paging activity.
These are averaged each five seconds, and given in
units per second.
Page reclaims (without
Address translation faults (without
Processes swapped in (with
Processes swapped out (with
Pages paged in
Pages paged out
Pages freed per second
Anticipated short term memory shortfall
Pages scanned by clock algorithm, per second
Trap/interrupt rate averages per second over last 5 seconds.
Device interrupts per second (nonclock)
System calls per second
CPU context switch rate (switches/sec)
Breakdown of percentage usage of CPU time for the active proces‐
sors
User time for normal and low priority processes
System time
CPU idle
EXAMPLES
The following examples show the output for various command options.
For formatting purposes, some leading blanks have been deleted.
1. Display the default output.
2. Add the disk tranfer information to the default output.
3. Display the default output in 80-column format.
4. Replace the page reclaims and address translation faults with
process swapping in the default output.
5. Display the default output twice at five-second intervals. Note
that the headers are repeated.
6. Display the default output twice in 80-column format at five-
second intervals. Note that the headers are repeated.
7. Display the default output and disk transfers twice in 80-column
format at five-second intervals. Note that the headers
repeated.
8. Display the number of forks and pages of virtual memory since
boot-up.
9. Display the counts of paging-related events.
WARNINGS
Users of 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
was developed by the University of California, Berkeley and HP.
SEE ALSOiostat(1).
vmstat(1)
