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.\" @(#)vmstat.8 8.1 (Berkeley) 6/6/93
.TH VMSTAT 1 "June 6, 1993"
vmstat \- report virtual memory statistics
vmstat [ \-ims ] [ \-c count ] [ \-M core ] [ \-N system ]
reports certain kernel statistics kept about process, virtual memory,
disk, trap and cpu activity.
The options are as follows:
The first display is for the time since a reboot and each subsequent report
is for the time period since the last display.
interval is specified, the default is 1 second.
.\" system calls since system startup, and the number of pages of virtual memory
Report on the number of interrupts taken by each device since system
Extract values associated with the name list from the specified core
instead of the default ``/dev/kmem''.
Extract the name list from the specified system instead of the default
Report on the usage of kernel dynamic memory listed first by size of
allocation and then by type of usage.
Display the contents of the
structure, giving the total number of several kinds of paging related
events which have occurred since system startup.
.\" Report on the number of page in and page reclaims since system startup,
.\" and the amount of time required by each.
seconds between each display.
is specified, the default is infinity.
displays the following information:
Information about the numbers of processes in various states.
b blocked for resources (i/o, paging, etc.)
w runnable or short sleeper (< 20 secs) but swapped
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
fre size of the free list
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)
fr pages freed per second
de anticipated short term memory shortfall
sr pages scanned by clock algorithm, per-second
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
If more than four disk drives are configured in the system,
displays only the first four drives.
to display specific drives, their names may be supplied on the command line.
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)
Breakdown of percentage usage of CPU time.
us user time for normal and low priority processes
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.
/vmunix default kernel namelist
/dev/kmem default memory file
The sections starting with ``Interpreting system activity'' in
.IR "Installing and Operating 4.3BSD" .
The \-c and \-w options are only available with the default output.