VMSTAT(1)VMSTAT(1)NAMEvmstat - report virtual memory statistics
SYNOPSISvmstat [ -fimst ] [ -c count ] [ -M core ] [ -N system ]
[ -w wait ] [ disks ]
DESCRIPTION
Vmstat reports certain kernel statistics kept about process, virtual
memory, disk, trap and cpu activity.
The options are as follows:
-c 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 speci‐
fied, the default is 1 second.
-f Report on the number fork(2) and vfork(2) system calls 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 Extract values associated with the name list from the specified
core instead of the default ``/dev/kmem''.
-N Extract the name list from the specified system instead of the
default ``/vmunix''.
-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.
-w Pause wait seconds between each display. If no repeat count is
specified, the default is infinity.
By default, vmstat displays the following information:
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.
re page reclaims (simulating reference bits)
at pages attached (found in free list)
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
disks Disk operations per second (this field is system dependent).
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 four disk drives are configured
in the system, vmstat displays only the first four drives. To
force vmstat to display specific drives, their names may be sup‐
plied on the command line.
faults Trap/interrupt rate averages per second over last 5 seconds.
in device interrupts per interval (including clock interrupts)
sy 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
EXAMPLES
The command ``vmstat -i 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.
FILES
/vmunix default kernel namelist
/dev/kmem default memory file
SEE ALSOfstat(1), netstat(1), nfsstat(1), ps(1), systat(1), iostat(8), pstat(8)
The sections starting with ``Interpreting system activity'' in
Installing and Operating 4.3BSD.
BUGS
The -c and -w options are only available with the default output.
4th Berkeley Distribution June 6, 1993 VMSTAT(1)
