NAME

vmstat − report virtual memory statistics

SYNOPSIS

vmstat [ −dfsSz ] [ interval [ count ] ]

DESCRIPTION

Vmstat normally reports certain statistics kept about process, virtual memory, trap and cpu activity.  If given a −d argument, it also reports disk transfer information in the form of transfers per second.  If given a −f argument, it instead reports on the number of forks and vforks since system startup and the number of pages of virtual memory involved in each kind of fork.  If given a −s argument, it instead prints the contents of the sum structure, giving the total number of several kinds of paging related events that have occurred since boot.  Giving a −S argument causes vmstat to execute normally with the exception that the number of processes swapped in and out are displayed instead of page reclaims and address translation faults.  The −z option requires super-user capabilities.  It clears all accumulators in the sum structure. 

If none of these options are given, vmstat will report in the first line a summary of the virtual memory activity since the system has been booted.  If interval is specified, then successive lines are summaries over the last interval seconds.  The command 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.  If a count is given, the statistics are repeated count times.  The format fields are:

Procs: information about 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 are considered active if they belong to processes that are running or have run in the last 20 seconds. 

avm active virtual pages

free 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

at address translation faults

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

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

sy system time

id cpu idle

AUTHOR

Vmstat was developed by the University of California, Berkeley California, Computer Science Division, Department of Electrical Engineering and Computer Science. 

FILES

/dev/kmem

/hp-ux

Hewlett-Packard Company  —  HP-UX Release 7.0: Sept 1989