vmstat

VMSTAT(1)						      General Commands Manual							 VMSTAT(1)

NAME

       vmstat - report virtual memory statistics

SYNOPSIS

       vmstat [ -fsi ] [ drives ] [ interval [ count ] ]

DESCRIPTION

       Vmstat  delves into the system and normally reports certain statistics kept about process, virtual memory, disk, trap and cpu activity.	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 which have occurred since boot.  If given a -i argument, it instead reports on the number of  inter-
       rupts taken by each device since system startup.

       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.  ``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.   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 which are
       running or have run in the last 20 seconds.  A ``page'' here is 1024 bytes.

       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

       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
       sy   system time
       id   cpu idle

       If  more  than  4  disk	drives	are configured in the system, vmstat 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 vmstat to display specific drives, their names may be supplied on the command
       line.

FILES

       /dev/kmem, /vmunix

SEE ALSO

       systat(1), iostat(1)

       The sections starting with ``Interpreting system activity'' in Installing and Operating 4.2bsd.

4th Berkeley Distribution					  March 15, 1986							 VMSTAT(1)