PJ40715: REDUCE OVERHEAD IN THE CACHE UNLOCK POLICE ROUTINE
Closed as program error.
See 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.
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
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NoSpecatt / Xsystem
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