VMSTAT(1) 1991 VMSTAT(1)
NAME
vmstat - report virtual memory statistics
SYNOPSIS
vmstat [ -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 specified, 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 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 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.
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VMSTAT(1) 1991 VMSTAT(1)
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 supplied 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
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VMSTAT(1) 1991 VMSTAT(1)
apparent which are recomputed every second.
FILES
/vmunix default kernel namelist
/dev/kmem default memory file
SEE ALSO
fstat(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.
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