OA35428: NEW FUNCTION: CICS RESPONSE TIME MANAGEMENT ENHANCEMENT

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APAR status

  • Closed as new function.

Error description

  • NEW FUNCTION: CICS Response Time Management Enhancement
    

Local fix

Problem summary

  • ****************************************************************
    * USERS AFFECTED: All users of z/OS 1.11 (HBB7760) and         *
    *                 above who run nearly an exclusively          *
    *                 CICS workload.                               *
    ****************************************************************
    * PROBLEM DESCRIPTION: NEW FUNCTION: CICS Response Time        *
    *                      Management Enhancement                  *
    *                                                              *
    *                      WLM management of CICS workload         *
    *                      adhering to a work manager/consumer     *
    *                      model might have negative effects in    *
    *                      environments which run nearly           *
    *                      exclusively CICS and process solely     *
    *                      online transactions and no other work   *
    *                      exists on the system which can be       *
    *                      displaced during contention periods.    *
    *                      When internal CICS queue contention     *
    *                      increases on such systems and the CICS  *
    *                      TORs and AORs are being managed to the  *
    *                      goals of the transactions, WLM          *
    *                      currently has no way to give the work   *
    *                      managers, the CICS TORs, faster access  *
    *                      to resources than the work consumers,   *
    *                      the CICS AORs. At higher utilization    *
    *                      levels, typically above 85%, a          *
    *                      noticeable queue delay within the CICS  *
    *                      TORs might be recognized. This reduces  *
    *                      end-to-end response time of the CICS    *
    *                      transactions and throughput of the CICS *
    *                      work. These symptoms become faster      *
    *                      visible in a HIPERDISPATCH=YES          *
    *                      environment.                            *
    *                                                              *
    *                      Furthermore, this APAR fixes two        *
    *                      problems with service IWM4MCHS          *
    *                      (Monitoring Change State of Work Unit): *
    *                      (1) The code generated by the macro     *
    *                      might work with an invalid address to   *
    *                      the PB when operating in AMODE(64)      *
    *                      causing unpredictable results.          *
    *                      (2) The code generated does not check   *
    *                      whether the PB has the EWLM-enabled     *
    *                      flag set before the service routine     *
    *                      IWMXDISW is called.  The overhead of    *
    *                      the unnecessary calls to IWMXDISW may   *
    *                      cause performance impacts to the        *
    *                      caller.                                 *
    ****************************************************************
    * RECOMMENDATION:                                              *
    ****************************************************************
    WLM manages CICS regions solely based on the transaction service
    class mix they are executing. Depending on that mix, WLM is
    generally not able to distinguish CICS TORs from AORs. But CICS
    work often adheres to a work manager/consumer model. That is,
    CICS TORs typically function as work receiver and sender of
    processing results, and just distribute the work to the CICS
    AORs which execute application programs on behalf of the
    request. For that, CICS TORs require only short, but very fast
    access to resources in order to avoid being a bottleneck, while
    CICS AORs typically run more resource intensive programs which
    do not require the same fast access to resources.
    
    The inability of WLM to distinguish TORs from AORs becomes
    apparent in environments which run nearly exclusively CICS and
    process solely online transactions and no other work exists on
    the systems which can be displaced during contention periods.
    In such environments, when internal CICS queue contention
    increases and the CICS TORs and AORs are being managed to the
    goals of the transactions, WLM has no way to give CICS TORs
    faster access to resources than AORs. As a result, at higher
    utilization levels - typically above 85% - noticeable queue
    (QRMod) delays within the TORs can be recognized. This reduces
    the end-to-end response times of the CICS transactions, and the
    throughput of CICS work.
    
    These symptoms become faster visible in a HIPERDISPATCH=YES
    environment, because there, the number of logical processors in
    use is minimized in order to increase cache hits and thereby
    throughput of the work in the system.
    
    A circumvention of the problem exists by exempting CICS regions
    from being managed using the goals of the transaction service
    classes.  This means that CICS regions are managed towards the
    velocity goals of the started task or JES service classes for
    the regions. The drawback of this solution is that transaction
    statistics are no longer available for managing CICS work and
    only through report classes - if defined - for reporting
    purposes. This reduces the capabilities of WLM to
    reporting-only.
    
    This APAR introduces a new option BOTH for managing CICS
    regions. Regions managed using the goals of BOTH are managed
    towards the velocity goals of the started task or JES service
    class for the region, but all transaction completions are still
    tracked so that WLM can still manage the CICS service classes
    with response time goals.
    
    Option BOTH should only be used for CICS TORs that experience
    noticeable queue delays at higher utilization levels. All CICS
    AORs should remain at the default TRANSACTION. Furthermore, the
    started task or JES service class for the CICS TORs should be
    defined with a higher importance than the response time service
    classes for the CICS transactions. This enables WLM to give CICS
    TORs fast access to resources, especially CPU, while it can
    still manage the larger part of the CICS workload in the AORs
    towards response time goals.
    
    The problems with service IWM4MCHS are caused by the following:
    (1) The code generated by the macro uses the content of field
    MONTKN as an address to the PB (WLM performance block). Since it
    does not clear the high order bit, an invalid address results
    when the caller is operating in AMODE(64).
    (2) The macro does not check whether the PB has the EWLM-enabled
    flag set before calling the service routine IWMXDISW. If the
    work request does not participate in EWLM, the invocation of
    IWMXDISW is not necessary.
    

Problem conclusion

Temporary fix

Comments

  • This APAR introduces a new option BOTH for adjusting WLM
    management of CICS regions to a work manager/consumer model.
    
    The WLM Administrative Application is extended to support the
    new option. The classification rules panel for subsystem types
    STC and JES now allows besides TRANSACTION and REGION the new
    value BOTH for column 'Manage Region Using Goals Of'.
    
    Then, WLM management is adjusted for regions managed using the
    goals of BOTH. For that, the new option is stored in various
    control blocks and propagated back and forth between them so
    that it can be set and read by the WLM Administrative
    Application and z/OSMF, and services like REQASD, REQFASD,
    REQSVDAT and IWMRQRY:
    
       Macro    | Short Description of what has been changed
       ---------+----------------------------------------------
       IRAOUCBX | New flag OucbxTrxMgmtBothSpecified
       IRARASD  | New flag RasdTrxnMgmtBoth
       IRARQSRV | New flag RqsvTrxnMgmtBoth
       IRASASAS | New flag SAS_AS_REPT_TrxnMgmtBoth
       IRASMF99 | New flag SMF99_AS_MANAGED_TO_BOTH_GOALS
       IWMSRMTK | New flag SrmTkTrxnMgmtBoth
       IWMSVDCR | New flag SVDCRTRB
       IWMSVPCR | New flag SVPCRTRB
       IWMWRQAA | New flag RqaeTrxnMgmtBoth
    
    The actual implementation of the new option is in IRAPATOP,
    which determines the service class for server address spaces
    based on the external response time service class mix they
    serve. IRAPATOP is modified so that server address spaces with
    new option BOTH are managed towards the goals of their original
    started task or JES service class.  In contrast to server
    address spaces exempted from transaction management, report and
    notify processing in IRARMWL3 is unchanged for them, so that
    transaction completions and execution times are gathered for
    management and reporting.
    
    The IWM4SRSC service for obtaining server specific routing
    information is adjusted for server address spaces managed using
    the goals of BOTH. As these server address spaces act as work
    managers and just distribute the work to other regions, their
    weight must not be calculated based on their started task or JES
    service class by which they are managed. Instead, IWMW4SR1 is
    modified so that for these server address spaces the weight
    calculation is based on the external response time service class
    with the highest importance and transaction rate they serve.
    
    Usage Information:
    ==================
    
    1. The new option BOTH should be used for CICS TORs only. All
       CICS AORs should remain at the default TRANSACTION. In
       addition, the started task or JES service class for CICS TORs
       should be defined with a higher importance than the response
       time service classes for the CICS transactions. This enables
       WLM to give CICS TORs fast access to resources, especially
       CPU, while it can still manage the larger part of the CICS
       workloads running in the AORs towards response time goals.
    
    2. When a service definition containing new option BOTH is
       installed, the WLM Administrative Application displays a
       confirmation panel that asks whether the preconditions for
       using BOTH are met:
    
       - All systems running z/OS V1R11 or higher
       - APAR OA35428 installed on all systems
    
       If APAR OA35428 is not installed on a system in the sysplex,
       or a system is running z/OS V1R10 or lower, option BOTH is
       treated there like the default TRANSACTION in WLM management,
       reporting, and the Administrative Application.
    
    3. APAR OA35428 makes APAR OA34801 obsolete. Support for IEAOPT
       parameter REPORTCOMPLETIONS introduced with APAR OA34801 is
       therefore removed in z/OS V1R13 and higher. In z/OS V1R11 and
       z/OS V1R12 it is still supported, but not recommended to
       adjust WLM management of CICS regions to a work
       manager/consumer model.  Instead, the new option BOTH is the
       recommended solution.
    
    In addition to the new function being added the following minor
    updates were made:
    
    The code generated by macro IWM4MCHS is fixed as follows:
    (1) The high order bit of field MONTKN is cleared before the
    address to the PB is established.
    (2) The code checks whether the PB has the EWLM-enabled flag
    set before the service routine IWMXDISW is called.
    
    Macro IRARMCTZ has been updated with a less confusing
    comment for flag RMCTZ_ABN_OPT.
    
    
    For the documentation updates related to this APAR, please
    refer to:
     http://publibz.boulder.ibm.com/zoslib/pdf/OA35428.pdf
    

APAR Information

  • APAR number

    OA35428

  • Reported component name

    WORK LOAD MANAG

  • Reported component ID

    5752SCWLM

  • Reported release

    760

  • Status

    CLOSED UR1

  • PE

    NoPE

  • HIPER

    NoHIPER

  • Special Attention

    NoSpecatt

  • Submitted date

    2011-02-01

  • Closed date

    2011-07-28

  • Last modified date

    2011-09-02

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

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

    UA61417 UA61418 UA61459

Modules/Macros

  •    IEAVNP10 IRABASMF IRACLFSC IRAEVJJT IRAEVREQ
    IRAOLST  IRAOUCBX IRAPASSB IRAPASS1 IRAPASS2 IRAPASS3 IRAPASS4
    IRAPASS5 IRAPASS6 IRAPASS7 IRAPASS8 IRAPAS2D IRAPATOP IRARASD
    IRARMASD IRARMCTZ IRARMOPT IRARMSMF IRARMSOP IRARQSRV IRASAMSU
    IRASASAS IRASASRV IRASETNP IRASMF99 IWMAM70  IWMAPAB  IWMAPLGO
    IWMAPTTG IWMARDCF IWMARI2X IWMARX2I IWMAR01  IWMAR7D  IWMATQT
    IWMA2SD2 IWMC4SMF IWMHTB1  IWMH7CG  IWMH7DF  IWMH7DJ  IWMH7DO
    IWMP2ECR IWMP2PRQ IWMP2RE2 IWMP2VDR IWMP2VPR IWMSRMTK IWMSVDCR
    IWMSVPCR IWMWRCAA IWMWRQAA IWMW2BCL IWMW3MLD IWMW4SR1 IWMZ2VCR
    IWM4MCHP IWM4MCHS
    

Publications Referenced
SA22761919 SA22761920 SA22760218 SA22760219 SA22763021
SA22763022        

Fix information

  • Fixed component name

    WORK LOAD MANAG

  • Fixed component ID

    5752SCWLM

Applicable component levels

  • R760 PSY UA61417

       UP11/08/10 P F108

  • R770 PSY UA61418

       UP11/08/10 P F108

  • R780 PSY UA61459

       UP11/08/10 P F108

Fix is available

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Document information


More support for:

z/OS family

Software version:

760

Operating system(s):

MVS, z/OS

Reference #:

OA35428

Modified date:

2011-09-02

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