VMSTAT(8) OpenBSD System Manager's Manual VMSTAT(8)
vmstat - report statistics about kernel activities
vmstat [-c count] [-M core] [-N system] [-w wait] [disks]
vmstat reports certain kernel statistics kept about process, virtual mem-
ory, disk, trap and CPU activity.
The options are as follows:
Repeat the display 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 wait interval is specified,
the default is 1 second.
-f Report on the number of fork(2), rfork(2) and vfork(2) system
calls as well as kernel thread creations since system startup,
and the number of pages of virtual memory involved in each.
-i Report on the number of interrupts taken by each device since
Extract values associated with the name list from the specified
core instead of the running kernel.
Extract the name list from the specified system instead of the
-m Report on the usage of kernel dynamic memory listed first by size
of allocation and then by type of usage.
-s Display the contents of the sum structure, giving the total num-
ber of several kinds of paging related events which have occurred
since system startup.
-t Report on the number of page in and page reclaims since system
startup, and the amount of time required by each.
Pause wait seconds between each display. If no repeat count is
specified, the default is infinity.
-v Print more verbose information.
-z When used with -i, also list devices which have not yet generated
By default, vmstat displays the following information just once:
procs Information about the 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. Virtu-
al pages (reported in units of 1024 bytes) are considered ac-
tive if they belong to processes which are running or have run
in the last 20 seconds.
avm active virtual pages
fre 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.
flt page faults
re page reclaims (simulating reference bits)
at pages attached (found in free list)
pi pages paged in
po pages paged out
fr pages freed
sr pages scanned by clock algorithm
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 two disk drives are configured in the system, vmstat dis-
plays only the first two drives. To force vmstat to display
specific drives, their names may be supplied on the command
traps Trap/interrupt rate averages per second over last 5 seconds.
int device interrupts per interval (including clock interrupts)
sys system calls per interval
cs CPU context switch rate (switches/interval)
cpu Breakdown of percentage usage of CPU time.
us user time for normal and low priority processes
sy system time
id CPU idle
The command 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 of-
ten 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.
fstat(1), netstat(1), nfsstat(1), procmap(1), ps(1), systat(1),
The sections starting with ``Interpreting system activity'' in Installing
and Operating 4.3BSD.
The -c and -w options are only available with the default output.
This manual page lacks an incredible amount of detail.
OpenBSD 3.6 June 6, 1993 2