vmstat - report statistics about kernel activities
vmstat [-fimstvz]
vmstat [-c count] [-M core] [-N system] [-w wait] [disks]
vmstat reports certain kernel statistics kept about process,
virtual memory,
disk, trap and CPU activity.
The options are as follows:
-c count
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
system startup.
-M core
Extract values associated with the name list from
the specified
core instead of the running kernel.
-N system
Extract the name list from the specified system instead of the
running kernel.
-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 number
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.
-w wait
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
an interrupt.
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. 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.
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 displays
only the first two drives. To force vmstat
to display
specific drives, their names may be supplied on
the command
line.
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 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.
fstat(1), netstat(1), nfsstat(1), procmap(1), ps(1), systat(1),
iostat(8), pstat(8)
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
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