PJ40766: PROVIDE PDU THROTTLING MECHANISM

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APAR status

  • Closed as program error.

Error description

  • See Problem Summary.
    

Local fix

  • na
    

Problem summary

  • APAR NUMBER:  PJ40766
    PRODUCT:  z/TPF
    FUNCTIONAL AREA:  POOLS
    SHIPPED IN PUT:  10
    
    ABSTRACT:
    Enhancement to ZRPDU CREATE to limit the number of ECBs that it
    uses.
    
    PACKAGE CONTENTS:
    Source Segments:
    (C) base/include/tpf/c_bk0rp.h
    (N) base/include/tpf/c_bl0rf.h
    (C) base/include/tpf/i_pdu.h
    (C) base/macro/bk0rp.mac
    (C) base/rt/bof7.asm
    (C) base/rt/bofa.asm
    (C) base/rt/pdu_mr_processing.c
    
    Object Only Binaries:
    None.
    
    Configuration Independent Binaries:
    (C) base/lib/libBSSA.so
    (C) base/load/BSSA.so
    (C) base/obj/pdu_mr_processing.o
    
    Support Files:
    base/lst/BSSA.map
    base/lst/pdu_mr_processing.lst
    
    OTHER BINARIES TO BUILD: YES
    (C) <sys>/load/BOF7.so
    (C) <sys>/load/BOFA.so
    (C) <sys>/obj/bof7.o
    (C) <sys>/obj/bofa.o
    
    COMMENTS:
    The first step in a pool directory update (PDU) is to run
    command ZRPDU CREATE. ZRPDU CREATE takes release file
    information and populates pseudo directories. Multiple ECBs are
    used by ZRPDU CREATE to get the release file information from
    CA records that are referenced out of FC33 records (dsect
    I80I8) and update the appropriate pseudo directory.
    
    Currently, ZRPDU CREATE has controls to limit the number of
    ECBs that it uses. Macro LODIC CLASS=IBMBATCH is executed to
    determine whether ECBs are available before a new ECB is
    created. Typically, the shutdown level for LODIC CLASS=IBMBATCH
    is 48% of available ECBs. In a system where a larger number of
    ECBs are allocated, ZRPDU CREATE can use a large number of
    ECBs. For example, if 2000 ECBs are allocated, ZRPDU CREATE
    will stop creating new ECBs when 960 or fewer ECBs are
    available. This means that 1040 or more ECBs will be in use.
    Obviously, not all of these in use ECBs will be for ZRPDU
    CREATE, but it is possible that a large percentage of the in
    use ECBs will be for ZRPDU CREATE.
    
    ZRPDU CREATE is processor intensive. For every released file
    address it does the following. The IPART table is searched to
    determine the directory where the file address lives. A find is
    done on the pseudo directory. The appropriate bit in the
    directory is updated. Lastly, the psuedo directory is filed.
    The pseudo directories are intended to be delay file in VFA. As
    a result, when the find is done, the ECB does not give up
    control.
    
    Because ZRPDU CREATE is processor intensive and because it can
    use a large number of ECBs, it can drive processor utilization
    to 100% on all I-streams. When TPF is running in a dedicated
    LPAR, driving processor utilization to 100% is not a problem.
    PDU controls effectively give PDU a lower priority than
    transactional traffic. In this case it makes sense to use all
    available resources to complete PDU.
    
    However, when TPF is running in a shared LPAR, driving all TPF
    I-streams to 100% may affect other shared LPARs that are on the
    same machine. In this case there needs to be better controls
    for the number of ECBs that ZRPDU CREATE uses.
    

Problem conclusion

  • SOLUTION:
    An additional control is now available for ZRPDU CREATE.
    Command ZRPDU CNTL has been updated to allow users to set the
    maximum allowed number of ECBs that ZRPDU CREATE will use when
    populating the pseudo directories. The format for this new
    option is ZRPDU CNTL SET MAXECBS-value. In addition, ZRPDU CNTL
    has the ability to display the current setting for the maximum
    allowed number of ECBs. The format for this new option is ZRPDU
    CNTL DISPLAY MAXECBS.
    
    The use of LODIC CLASS=IBMBATCH still exists. LODIC
    CHECK,CLASS=IBMBATCH is executed by ZRPDU CREATE when a new ECB
    is created. This new control for the maximum allowed ECBs is in
    addition to the LODIC CLASS=IBMBATCH control.
    
    The initial value for the maximum allowed number of ECBs for
    ZRPDU CREATE is zero. This allows ZRPDU CREATE to operate the
    same way that it does prior to this enhancement. In this case
    LODIC CLASS=IBMBATCH is the only control.
    
    It is possible to change the maximum allowed ECBs value while
    ZRPDU CREATE is active.
    
    Lastly, the logic that ZRPDU CREATE uses to populate pseudo
    directories is also used by Recoup. The Recoup 'PRE' phase 1
    release pass and the Recoup 'DURING' phase 1 release pass uses
    this logic. Because the same logic is used, this new control
    for the maximum allowed number of ECBs is also used. Therefore,
    ZRPDU CNTL SET MAXECBS is used to limit ECBs when Recoup
    processes pre Recoup release files and when Recoup processes
    during Recoup release files.
    
    COREQS: NO
    None.
    
    MIGRATION CONSIDERATIONS: YES
    Functional, automation, and operation changes:
    Changed commands:
    ZRPDU CNTL
    
    New messages:
    RPDU0005I
    RPDU0006I
    RPDU0017E
    RPDU0018E
    RPDU0019E
    
    
    Installation validation:
    In order to determine a reasonable value for ZRPDU CNTL SET
    MAXECB, you should run one or more PDUs with the maximum
    allowed number of ECBs set to 0.  During ZRPDU CREATE, do
    display ZRPDU CNTL DISPLAY MAXECBS.  This will give you not
    only the maximum allowed number of ECBS, but also the number of
    ECBs that are currently in use.  By doing several ZRPDU CNTL
    DISPLAY MAXECBS commands, you will understand the number of
    ECBS that are being used by ZRPDU CREATE.
    
    Coexistence, migration, and fallback considerations:
    After installing PJ40766 and before the first PDU is run, you
    should display the maximum number of allowed ECBs for ZRPDU
    CREATE.  Do command ZRPDU CNTL DISPLAY MAXECBS.  The purpose is
    to validate that the default setting for maximum number of ECBs
    is zero.
    
    
    
    BUILD COMMANDS AND INSTRUCTIONS: YES
    #maketpf commands for linux
    maketpf -f BSSA pdu_mr_processing.o
    maketpf -f BOFA bofa.o
    maketpf -f BOF7 bof7.o
    maketpf BSSA link TPF_VERIFY_LINK_REFS=NO
    maketpf BOFA link
    maketpf BOF7 link
    maketpf BSSA link
    
    UPDATED INFORMATION UNITS: YES
    z/TPF and z/TPFDF Migration Guide: PUT 2 and Later
    z/TPF Messages (Online, SQLCODEs, and errno Values)
    z/TPF Operations
    
    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/PJ40766.htm
    

Temporary fix

Comments

APAR Information

  • APAR number

    PJ40766

  • Reported component name

    Z/TPF

  • Reported component ID

    5748T1501

  • Reported release

    110

  • Status

    CLOSED PER

  • PE

    NoPE

  • HIPER

    NoHIPER

  • Special Attention

    NoSpecatt

  • Submitted date

    2012-11-28

  • Closed date

    2012-12-19

  • Last modified date

    2012-12-19

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

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

Publications Referenced
SK2T8062        

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 #:

PJ40766

Modified date:

2012-12-19

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