vmstat



VMSTAT(8)               OpenBSD System Manager's Manual              VMSTAT(8)


NAME

     vmstat - report statistics about kernel activities


SYNOPSIS

     vmstat [-fimstvz]
     vmstat [-c count] [-M core] [-N system] [-w wait] [disk ...]


DESCRIPTION

     vmstat reports certain kernel statistics kept about process, virtual
     memory, disk, trap, and CPU activity.  The default behavior is to print a
     one-line summary of these statistics.  The -c and -w flags may be used to
     continually report summaries.

     The options are as follows:

     -c count
             Repeat the display count times.  The first display is for the
             time since a reboot and each subsequent report is for the time
             period since the last display.  If no wait interval is specified,
             the default is 1 second.

     -f      Report on the number of fork(2), __tfork(2), and vfork(2) system
             calls as well as kernel thread creations since system startup,
             and the number of pages of virtual memory involved in each.

     -i      Report on the number of interrupts taken by each device since
             system startup.

     -M core
             Extract values associated with the name list from the specified
             core instead of the running kernel.

     -m      Report on the usage of kernel dynamic memory listed first by size
             of allocation and then by type of usage.

     -N system
             Extract the name list from the specified system instead of the
             running kernel.

     -s      Display the contents of the uvmexp structure (see uvm(9)), giving
             the total number of several kinds of paging related events which
             have occurred since system startup.

     -t      Report on the number of page in and page reclaims since system
             startup, and the amount of time required by each.

     -v      Print more verbose information.

     -w wait
             Pause wait seconds between each display.  If no repeat count is
             specified, the default is infinity.

     -z      When used with -i, also list devices which have not yet generated
             an interrupt.

     By default, vmstat displays the following information just once:

     procs   Information about the 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 (reported in units of 1024 bytes) are considered active if
             they belong to processes which are running or have run in the
             last 20 seconds.

             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.

             flt   page faults
             re    page reclaims (simulating reference bits)
             at    pages attached (found in free list)
             pi    pages paged in
             po    pages paged out
             fr    pages freed
             sr    pages scanned by clock algorithm

     disks   Disk transfers per second.  Typically paging will be split across
             the available drives.  The header of the field is the first
             character of the disk name and the unit number.  If more than two
             disk drives are configured in the system, vmstat displays only
             the first two drives.  To force vmstat to display specific
             drives, their names may be supplied on the command line.

     traps   Trap/interrupt rate averages per second over last 5 seconds.

             int   device interrupts per interval (including clock interrupts)
             sys   system calls per interval
             cs    CPU context switch rate (switches/interval)

     cpu     Breakdown of percentage usage of CPU time.

             us    user time for normal and low priority processes
             sy    system time
             id    CPU idle


FILES

     /bsd                              default kernel image
     /dev/kmem                         default memory file


EXAMPLES

     The command vmstat -w 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 and running the output for a while will make it apparent
     which are recomputed every second.


SEE ALSO

     fstat(1), netstat(1), nfsstat(1), procmap(1), ps(1), systat(1), top(1),
     iostat(8), pstat(8), uvm(9)


BUGS

     The -c and -w options are only available with the default output.

     This manual page lacks an incredible amount of detail.

OpenBSD 5.4                     April 12, 2012                     OpenBSD 5.4

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