


VMSTAT(1)	    UNIX Programmer's Manual		VMSTAT(1)



NAME
     vmstat - report virtual memory statistics

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

DESCRIPTION
     _V_m_s_t_a_t 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 _f_o_r_k_s and _v_f_o_r_k_s 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 _s_u_m 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 _i_n_t_e_r_r_u_p_t_s taken by each device
     since system startup.

     If none of these options are given, _v_m_s_t_a_t will report in
     the first line a summary of the virtual memory activity
     since the system has been booted.	If _i_n_t_e_r_v_a_l is specified,
     then successive lines are summaries over the last _i_n_t_e_r_v_a_l
     seconds.  ``vmstat 5'' will print what the system is doing
     every five seconds; this is a good choice of printing inter-
     val since this is how often some of the statistics are sam-
     pled in the system; others vary every second, running the
     output for a while will make it apparent which are recom-
     puted every second.  If a _c_o_u_n_t is given, the statistics are
     repeated _c_o_u_n_t 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)



Printed 11/26/99	 March 15, 1986                         1






VMSTAT(1)	    UNIX Programmer's Manual		VMSTAT(1)



     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 sys-
     tem 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,
     _v_m_s_t_a_t 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 _v_m_s_t_a_t to display
     specific drives, their names may be supplied on the command
     line.

FILES
     /dev/kmem, /vmunix

SEE ALSO
     _s_y_s_t_a_t(1), _i_o_s_t_a_t(1)

     The sections starting with ``Interpreting system activity''
     in _I_n_s_t_a_l_l_i_n_g _a_n_d _O_p_e_r_a_t_i_n_g _4._2_b_s_d.














Printed 11/26/99	 March 15, 1986                         2



