PJ40715: REDUCE OVERHEAD IN THE CACHE UNLOCK POLICE ROUTINE

APAR status

• Closed as program error.

Error description

• See Problem Summary.
  

Local fix

• na
  

Problem summary

• APAR NUMBER:  PJ40715
  PRODUCT:  z/TPF
  FUNCTIONAL AREA:  POOLS
  SHIPPED IN PUT:  10
  
  ABSTRACT:
  Reduce overhead in DASD cached unlock police routine.
  
  PACKAGE CONTENTS:
  Source Segments:
  (C) base/cp/cjim.cpy
  
  Object Only Binaries:
  None.
  
  Configuration Independent Binaries:
  None.
  
  Support Files:
  None.
  
  OTHER BINARIES TO BUILD: YES
  (C) <sys>/obj/ccsons.o
  (C) <sys>/load/CPS0.so
  
  COMMENTS:
  In a loosely coupled system the DASD cached unlock police
  routine is called every 100 milliseconds. This DASD cached
  unlock police routine is at label CJIMSCUL in cjim.cpy in CP
  CSECT CCSONS. This cached unlock police routine will look for
  cached unlocks in every online entry in the module file status
  table (MFST). For each MFST entry, the logic will first lock
  the MFST entry and then determine if a cached unlock exists. If
  a cached unlock exists, the unlock request is driven and then
  the MFST lock for this entry is released. If no cached unlock
  exists, there is no work to do and the MFST lock for this entry
  is released. As a result, every 100 milliseconds every online
  MFST entry is locked and unlocked.
  
  In order to know for certain that a cached unlock exists in an
  MFST entry, the MFST entry must be locked. However, locking the
  MFST entry is not needed to know that a cached unlock does not
  exist in an MFST entry. Rather the logic can first look to
  determine if a cached unlock exists and only lock the MFST
  entry if the initial check found that a cached unlock exists.
  

Problem conclusion

• SOLUTION:
  Routine CJIMSCUL in cjim.cpy in CP CSECT CCSONS has been
  updated. Every MFST entry is still checked to determine whether
  a cached unlock exists. However, the logic will first check to
  determine if a cached unlock exists in an MFST entry. If no
  cached unlock exists, then there is no need to lock the MFST
  entry. Processing goes to the next MFST entry. If a cached
  unlock exists, then the MFST entry is locked and the same check
  to determine if a cached unlock exists is performed again. This
  change will reduce the amount of locking that is done in the
  cached unlock police routine.
  
  COREQS: NO
  None.
  
  MIGRATION CONSIDERATIONS: NO
  None.
  
  BUILD COMMANDS AND INSTRUCTIONS: YES
  #maketpf commands for linux
  maketpf -f CPS0 ccsons.o
  maketpf CPS0 link
  
  UPDATED INFORMATION UNITS: NO
  None.
  
  See your IBM representative if you need additional information.
  
  DOWNLOAD INSTRUCTIONS:
  http://www.ibm.com/software/htp/tpf/maint/maintztpf.html
  
  APAR URL:
  http://www.ibm.com/software/htp/tpf/ztpfmaint/put10/PJ40715.htm
  

Temporary fix

Comments

APAR Information

• APAR is sysrouted FROM one or more of the following:

• APAR is sysrouted TO one or more of the following:

Fix information

• Fixed component name

  Z/TPF

• Fixed component ID

  5748T1501

Applicable component levels

• R110 PSY

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