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.\" @(#)vmstat.8 6.5 (Berkeley) %G%
vmstat \- report virtual memory statistics
delves into the system and normally reports certain statistics kept about
process, virtual memory, disk, trap and cpu activity.
argument, it instead reports on the number of
since system startup and the number of pages of virtual memory involved in each
argument, it instead prints the contents
structure, giving the total number of several kinds of paging related
events which have occurred since boot.
argument, it instead reports on the number of
taken by each device since system startup.
argument, it instead reports on the usage of
kernel dynamic memory listed first by
of allocation and then by
If none of these options are given,
will report in the first line a summary of the virtual memory activity
since the system has been booted.
is specified, then successive lines are summaries over the last
``vmstat 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, running the output for a while will make it apparent which
are recomputed every second.
is given, the statistics are repeated
Procs: information about numbers of processes in various states.
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 are considered active if they belong to processes which
are running or have run in the last 20 seconds.
A ``page'' here is 1024 bytes.
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)
fr pages freed per second
de anticipated short term memory shortfall
sr pages scanned by clock algorithm, per-second
up/hp/rk/ra: Disk operations per second (this field is system dependent).
Typically paging will be split across several of the available drives.
The number under each of these is the unit number.
Faults: trap/interrupt rate averages per second over last 5 seconds.
in (non clock) device interrupts per second
sy system calls per second
cs cpu context switch rate (switches/sec)
Cpu: breakdown of percentage usage of CPU time
us user time for normal and low priority processes
If more than 4 disk drives are configured in the system,
displays only the first 4 drives, with priority given
to Massbus disk drives (i.e. if both Unibus and Massbus
drives are present and the total number of drives exceeds
4, then some number of Unibus drives will not be displayed
in favor of the Massbus drives). To force
to display specific drives, their names may be supplied on
The sections starting with ``Interpreting system activity'' in
.IR "Installing and Operating 4.2bsd" .