PJ40715: REDUCE OVERHEAD IN THE CACHE UNLOCK POLICE ROUTINE

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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 number

    PJ40715

  • Reported component name

    Z/TPF

  • Reported component ID

    5748T1501

  • Reported release

    110

  • Status

    CLOSED PER

  • PE

    NoPE

  • HIPER

    NoHIPER

  • Special Attention

    NoSpecatt

  • Submitted date

    2012-11-13

  • Closed date

    2012-11-16

  • Last modified date

    2012-11-16

  • 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

       UP



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Document information


More support for:

TPF
z/TPF

Software version:

110

Reference #:

PJ40715

Modified date:

2012-11-16

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