PM83695: ZUDFM CAN CTL-10 DUE TO LODIC
Closed as program error.
See Problem Summary.
APAR NUMBER: PM83695 PRODUCT: z/TPFDF FUNCTIONAL AREA: TPFDF ZUDFM ROUTINES SHIPPED IN PUT: 10 ABSTRACT: ZUDFM INIT id NOHOLD processing, introduced by APAR PM26537, can drive up CPU utilization to 100 percent, potentially preventing deferred ECBs from being serviced. PACKAGE CONTENTS: Source Segments: (C) tpfdf/rt/ufd1.asm (C) tpfdf/macro/dfdfrc.mac Object Only Binaries: None. Configuration Independent Binaries: None. Support Files: None. OTHER BINARIES TO BUILD: YES (C) <sys>/obj/ufd1.o (C) <sys>/load/UFD1.so COMMENTS: ZUDFM INIT id NOHOLD issues a DLAYC after initializing 20 ordinals to prevent CTL-10s from occurring. The DLAYC macro places the ECB on the input list, potentially preventing the DEFER list from being processed. This can drive up the CPU utilization to 100 percent and prevent other lower priority lists on the CPU loop from dispatching ECBs. Additionally, ZUDFM INIT id NOHOLD defers when a LODIC check fails. The LODIC checks just IOBs and uses a high priority resource class (IBMHI) when additional system resoruces should be checked and a lower priority class should be used for a utility function. Futhermore, system resources are not being checked after returning from issuing the DLAYC.
SOLUTION: A new assembler system services macro has been introduced - DFDFRC (dfdfrc.mac). This macro will defer an entry control block (ECB) when the ECB is within 100 milliseconds of an application timeout (CTL-10 system error). The ZUDFM INIT id NOHOLD processing in ufd1.asm has changed as follows: - Instead of issuing a DLAYC every 20 ordinals, a DFDFRC macro will be issued. The ECB will now be put on the deferred list instead of the input list while still preventing the CTL-10. - The LODIC now checks more system resources (IOB,FRM,SWB) and uses a lower priorty class (IBMBATCH) before deferring. Additionally, system resources are checked after the ECB is deferred. COREQS: NO None. MIGRATION CONSIDERATIONS: YES Application programming interface (API) changes: New assembler system services API - DFDFRC BUILD COMMANDS AND INSTRUCTIONS: YES #maketpf commands for linux maketpf -f UFD1 ufd1.o maketpf UFD1 link UPDATED INFORMATION UNITS: YES z/TPFDF Programming Concepts and Reference 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/PM83695.htm
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