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

NAME
     vmstat -- report virtual memory statistics

SYNOPSIS
     vmstat [-afimsz] [-c count] [-M core [-N system]] [-w wait] [-n devs] [-p
            type,if,pass] [disks]

DESCRIPTION
     The vmstat utility reports certain kernel statistics kept about process,
     virtual memory, disk, trap and cpu activity.

     If the -M option is not specified, information is obtained from the cur-
     rently running kernel via the sysctl(3) interface.  Otherwise, informa-
     tion is read from the specified core file, using the name list from the
     specified kernel image (or from the default image).

     The options are as follows:

     -a      When used with -i, include statistics about interrupts that have
             never been generated.

     -c      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 repeat count is specified,
             and -w is specified, the default is infinity, otherwise the
             default is one.

     -f      Report on the number fork(2), vfork(2) and rfork(2) system calls
             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      Extract values associated with the name list from the specified
             core.

     -N      If -M is also specified, extract the name list from the specified
             system instead of the default, which is the kernel image the sys-
             tem has booted from.

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

     -n      Change the maximum number of disks to display from the default of
             2.

     -p      Specify which types of devices to display.  There are three dif-
             ferent categories of devices:

             device type:
                     da         Direct Access devices
                     sa         Sequential Access devices
                     printer    Printers
                     proc       Processor devices
                     worm       Write Once Read Multiple devices
                     cd         CD devices
                     scanner    Scanner devices
                     optical    Optical Memory devices
                     changer    Medium Changer devices
                     comm       Communication devices
                     array      Storage Array devices
                     enclosure  Enclosure Services devices
                     floppy     Floppy devices

             interface:
                     IDE        Integrated Drive Electronics devices
                     SCSI       Small Computer System Interface devices
                     other      Any other device interface

             passthrough:
                     pass       Passthrough devices

             The user must specify at least one device type, and may specify
             at most one device type from each category.  Multiple device
             types in a single device type statement must be separated by com-
             mas.

             Any number of -p arguments may be specified on the command line.
             All -p arguments are ORed together to form a matching expression
             against which all devices in the system are compared.  Any device
             that fully matches any -p argument will be included in the vmstat
             output, up to two devices, or the maximum number of devices spec-
             ified by the user.

     -s      Display the contents of the sum structure, giving the total num-
             ber of several kinds of paging related events which have occurred
             since system startup.

     -w      Pause wait seconds between each display.  If no repeat wait
             interval is specified, the default is 1 second.

     -z      Report on memory used by the kernel zone allocator, by zone.  The
             information shown is the same as that returned by the vm.zone
             sysctl variable.

     By default, vmstat displays the following information:

     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     total number of page faults
             re      page reclaims (simulating reference bits)
             pi      pages paged in
             po      pages paged out
             fr      pages freed per second
             sr      pages scanned by clock algorithm, per-second

     disks   Disk operations per second (this field is system dependent).
             Typically paging will be split across the available drives.  The
             header of the field is the first two characters 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, unless
             the user specifies the -n argument to increase the number of
             drives displayed.  This will probably cause the display to exceed
             80 columns, however.  To force vmstat to display specific drives,
             their names may be supplied on the command line.  The vmstat
             utility defaults to show disks first, and then various other ran-
             dom devices in the system to add up to two devices, if there are
             that many devices in the system.  If devices are specified on the
             command line, or if a device type matching pattern is specified
             (see above), vmstat will only display the given devices or the
             devices matching the pattern, and will not randomly select other
             devices in the system.

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

             in      device interrupts per interval (including clock inter-
                     rupts)
             sy      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
     /boot/kernel/kernel  default kernel namelist
     /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 statis-
     tics are sampled in the system.  Others vary every second and running the
     output for a while will make it apparent which are recomputed every sec-
     ond.

     The command:
           vmstat -p da -p cd -w 1
     will tell vmstat to select the first two direct access or CDROM devices
     and display statistics on those devices, as well as other systems statis-
     tics every second.

SEE ALSO
     fstat(1), netstat(1), nfsstat(1), ps(1), systat(1), gstat(8), iostat(8),
     pstat(8), sysctl(8)

     The sections starting with ``Interpreting system activity'' in Installing
     and Operating 4.3BSD.

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

FreeBSD 6.2                    February 11, 2005                   FreeBSD 6.2

NAME | SYNOPSIS | DESCRIPTION | FILES | EXAMPLES | SEE ALSO | BUGS

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