VIUBK Back to Index page
 
Prolog 
Control Block Contents 
   VIUBK DSECT
Storage Layout 
Cross Reference (Contains links to field and bit definitions)
Programming Interface Information:
This information is NOT intended to be
used as Programming Interfaces of z/VM.


  VIUBK Prolog Top of page
 
 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 Control Block Content Top of page
 

 VIUBK DSECT Top of page
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 Storage Layout Top of page
 
          
*** 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
 
 
  VIUBK Cross Reference Top of page
 
 
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
 
This information is based on z/VM 6.3.0 Last updated on 22 May 2013 at 13:56:19 EDT.
Copyright IBM Corporation, 1990, 2013