Programming Interface Information:
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VIUBK
Control Block Contents
VIUBK DSECT
Cross Reference (Contains links to field and bit definitions)
VIUBK Prolog
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
VIUBK DSECT
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
*** 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
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
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