VMSTAT(1)                                                            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  sys‐
       tem  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 _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.   Vir‐
       tual  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  depen‐
       dent).   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  dis‐
       plays  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.



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