NAME       : HCPVIUBK
 DESCRIPTION: VDEV I/O Assist Utilization Block
 DSECT      : VIUBK
 FUNCTION   : To track a device's utilization of I/O Assist
 LOCATED BY : VDEVIUBK Field of VDEV - Virtual Device Control Block
 CREATED BY : VIUBK's are dynamically created by HCPIAXBL for I/O
              Assist eligible devices when we log on, attach a
              device, redefine a device (if VIUBK did not already
              exist).
 DELETED BY : VIUBK's are deleted by HCPIAXBL when a redefine makes
              a device ineligible, or by HCPVDBDL when it deletes the
              associated VDEV.
 SERIALIZED : The VDEVLOCK should be held when referencing VIUBK fields.
 RELOCATION CONSIDERATIONS : None
 NOTES      :
     - When the VIUBK is first built, VIUCNTOT is
       incremented.
     - A transition from IN to OUT is considered to pass
       through a LEAVING state, but to spend no time there.
     - (Therefore) The counters VIUCNTOT, VIUCNTIN and
       VIUCNTLV will all be within one of each other.  The
       state of the device could be determined from these
       counters - When CNTOT is one greater than the other
       two, the device should be in the OUT state.  When
       CNTLV is one less than the other two, the device
       should be in the IN state.  When they are all equal,
       the device should be in the LEAVING state.  If this
       is not true, this should be considered an error in
       the code maintaining the counters.

 VIUBK DSECT
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Hex   Dec Type/Val   Lng Label (dup)    Comments
---- ---- --------- ---- -------------- --------
0000    0 Structure      VIUBK          VDEV I/O Assist Utilization Block
0000    0 Dbl-Word     8 VIUSTAMP       Timestamp of last I/O Assist
                                        transition
0008    8 Bitstring    1 VIUSTATE       Describes the device state NOTES
                                        : This state field is for
                                        statistical purposes and NOTES :
                                        should not be used to determine
                                        the state of the NOTES : device
                                        by CP code.
          00000000       VIUISOUT       0 VIUISOUT Device is out of I/O
                                        Assist
          00000001       VIUISIN        1 VIUISIN Device is in I/O Assist
          00000002       VIULEAV        2 VIULEAV Device is LEAVING I/O
                                        Assist
0009    9 Bitstring    1 * (3)          RESERVED FOR FUTURE IBM USE
000C   12 Signed       4 VIUCNTIN       Count of transitions in I/O
                                        Assist
0010   16 Signed       4 VIUTIMIN       Total time spent in I/O Assist
                                        (in micro seconds)
0014   20 Signed       4 VIUCNTLV       Count of transitions leaving I/O
                                        I/O Assist
0018   24 Signed       4 VIUTIMLV       Total time spent leaving I/O
                                        Assist (in micro seconds)
001C   28 Signed       4 VIUCNTOT       Count of transitions out of I/O
                                        Assist
0020   32 Signed       4 VIUTIMOT       Total time spent out of I/O
                                        Assist (in micro seconds)
0024   36 Signed       4 *              RESERVED FOR FUTURE IBM USE
          00000005       VIUSIZE        (*-VIUBK+7)/8

 
*** VIUBK - VDEV I/O Assist Utilization Block
*
*     +-------------------------------------------------------+
*   0 |                       VIUSTAMP                        |
*     +------+--------------------+---------------------------+
*   8 |:STATE|////////////////////|         VIUCNTIN          |
*     +------+--------------------+---------------------------+
*  10 |         VIUTIMIN          |         VIUCNTLV          |
*     +---------------------------+---------------------------+
*  18 |         VIUTIMLV          |         VIUCNTOT          |
*     +---------------------------+---------------------------+
*  20 |         VIUTIMOT          |///////////////////////////|
*     +---------------------------+---------------------------+
*  28
*
*** VIUBK - VDEV I/O Assist Utilization Block

 
Symbol         Dspl Value
-------------- ---- -----
VIUCNTIN       000C
VIUCNTLV       0014
VIUCNTOT       001C
VIUISIN        0008 00000001
VIUISOUT       0008 00000000
VIULEAV        0008 00000002
VIUSIZE        0024 00000005
VIUSTAMP       0000
VIUSTATE       0008
VIUTIMIN       0010
VIUTIMLV       0018
VIUTIMOT       0020