NAME

vmstat − report virtual memory statistics

SYNOPSIS

vmstat [ −m ] [ interval [ count ] ]

DESCRIPTION

vmstat delves into the system and reports certain statistics kept about process, virtual memory, disk, trap and cpu activity. 

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.  “vmstat 5” will print what the system is doing every five seconds.  If a count is given, the statistics are repeated count times.  Count and interval must be integers greater than zero. 

If the −m option is specified, the bottom portion of the report will contain memory utilization for individual global and local memory pools. 

The format fields are:

free: information about the usage of virtual and real memory. 

phys kilobytes of unused (local and global) physical memory

swap kilobytes of unused swap space

vfault: information about page faults (page not valid).  A “page” here is 1024, 4096 or 8192 bytes depending on the architecture (See getpagesize(2)). 

dzer demand zero pages

cache pages reclaimed from the free list

file pages demand paged in from the file system

swap pages demand paged in from the swap devices

pfault: information about protection faults. 

cw pages copied on write. A duplicate copy of a page needed to be made so a process could write to it. 

steal protected pages stolen. The page in memory was used to write to since the current process constituted the only reference to the page. 

vhand: information about pages pushed from memory. 

fre pages placed on free list

usw unmodified pages which already exist on a swap device which were freed. 

ufl unmodified pages which already exist on a file system which were freed. 

Faults: trap/interrupt rate averages per second over last 5 seconds. 

int (non clock) device interrupts per second

sys 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

Procs: information about numbers of processes in various states (suppressed by -m option). 

r number of processes in memory and runnable

s number of processes swapped out but ready to run

dsk: Disk Activity (suppressed by -m option). 

hd∗/vd∗ 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. 

free mem: information about usage of physical memory (-m option only).  (See memory(7) for more information.) 

global kilobytes of unused global physical memory

cpu∗ kilobytes of unused local physical memory for a particular logical cpu, or set of logical cpus. 

FILES

/dev/kmem, /unix

SEE ALSO

swap(1M), pagesize(1), iostat(1), pstat(1M), memory(7)

BUGS

There should be a screen oriented program which combines vmstat and ps(1) in real time as well as reporting on other system activity. 

CX/UX User’s Reference Manual