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OA45297: SIGNIFICANT SYSTEM PERFORMANCE IMPACT AFTER ENABLING A SLIP PER TRAP WITH PVTMOD AND MODE=HOME BUT NO JOBNAME OR ASID.

A fix is available

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APAR status

  • Closed as program error.

Error description

  • A customer experienced significant performance impact after
    setting a SLIP similar to the following:
    
    SLIP SET,IF,PVTMOD=(XYZ,100),MODE=HOME,END
    
    Use of MODE=HOME with neither JOBNAME nor ASID specified can
    cause significant overhead, even if the SLIP is enabled but
    inactive (meaning the PVTMOD has not been loaded onto the system
    yet).  To monitor for MODE=HOME, SLIP processing activates cross
    memory/space switching hooks.  In the case of the above SLIP
    coded with MODE=HOME and with neither JOBNAME nor ASID
    specified, these hooks apply to every address space on the
    system rather than selectively to just one or two address
    spaces, resulting in the noted performance impact.  Note that
    the SLIP PRCNTLIM parameter offers protection only if PER
    interrupts are occurring.
    
    
    VERIFICATION STEPS:
    0) This assumes a system experiencing a performance problem.
    1) Use console command D SLIP to list SLIPs defined to system,
       and use D SLIP=xxxx to list specific SLIP traps.  Look for a
       PER trap that is ENABLED and has MODE=HOME specified,
       but has neither JOBNAME nor ASID specified.
    2) Verify that disabling the SLIP trap eliminates the
       performance problem: SLIP MOD,DISABLE,ID=xxxx
    

Local fix

  • Disable the PER trap using the following command:
    
    SLIP MOD,DISABLE,ID=xxxx
    

Problem summary

  • ****************************************************************
    * USERS AFFECTED: Users at HBB7790 using SLIP.                 *
    ****************************************************************
    * PROBLEM DESCRIPTION: Significant performance impact after    *
    *                      setting SLIP with MODE=HOME and without *
    *                      JOBNAME and ASID.                       *
    ****************************************************************
    * RECOMMENDATION:                                              *
    ****************************************************************
    Significant performance impact occurred after setting s SLIP
    with MODE=HOME specified without JOBNAME and ASID.
    

Problem conclusion

  • A new trap IeaSlipConfirm is created for DIAGxx. When
    IeaSlipConfirm is specified in DIAGxx, SLIP is to check if
    JOBNAME or ASID is specified when MODE=HOME is specified in
    the SLIP command. If both JOBNAME and ASID parameters were
    omitted, SLIP is to issue message IEE088D to prompt for reply
    to continue or cancel the command.
    
    Documentation for APAR OA45297
    
    The following publication will be updated as follows to add
    the new information in the indicated existing topic-
    
    SA23-1380-00 z/OS V2R1.0 MVS Initialization and Tuning Reference
    
    Topic: Chapter 31. DIAGxx (control common storage tracking and
           GFS trace)
    Subtopic: Statements/parameters for DIAGxx
              under section TRAPS NAME ( trapname1,{trapname2}... )
              add following new trap:
    
     IeaSlipConfirm
        SLIP is to check if JOBNAME or ASID is specified when
        MODE=HOME is specified in the SLIP command. If both JOBNAME
        and ASID parameters were omitted, SLIP is to issue message
        IEE088D to prompt for reply to continue or cancel the
        command. In the future it is possible that this trap would
        apply to additional SLIP operand checking confirmation.
    
    
    SA38-0674-00 z/OS V2R1.0 MVS System Messages, Vol 7 (IEB-IEE)
    
    Topic: Chapter 4. IEE messages
           add following new message:
    
    
     IEE088D      SLIP COMMAND SPECIFIES MODE=HOME WITHOUT
                  JOBNAME AND ASID. SPECIFY 'OK' OR 'CANCEL'
                              - or -
     IEE088D      SLIP ID=xxxx SPECIFIES MODE=HOME WITHOUT
                  JOBNAME AND ASID. SPECIFY 'OK' OR 'CANCEL'
    
     Explanation: A SLIP command was issued with MODE=HOME
     specified, but the JOBNAME and ASID parameters were omitted.
     The omission of these parameters may cause significant
     performance impact. Refer to the "Setting Effective SLIP PER
     Traps" section in the SLIP Command in the z/OS System Command
     book. The SLIP trap could have been set with the OK operand
     to avoid getting the message.
    
     In the message text:
    
     xxxx  The ID of the trap being set.
    
     System action: SLIP command processor waits for a response.
     If the response is 'OK', the trap will be set. If the
     response is 'CANCEL', the command will be cancelled.
    
     Operator response: One of the following:
     . If you want to set the trap as is, reply 'OK'.
     . If you want to avoid setting the trap, reply 'CANCEL'.
       You may then reissue the command with JOBNAME/ASID or
       without MODE=HOME.
    
     Source: SLIP
    
     Module: IEECB909
    
     Routing code: *
    
     Descriptor code: 5
    
    
    The following publication will be updated as follows to add
    the flagged information in the indicated existing topic-
    
    SA38-0666-00 z/OS V2R1.0 MVS System Commands
    
    Topic: SLIP Command
    
    Subtopic: Coding SLIP command parameters
    
      OK  For a SLIP SET trap, omits checking that could result
    |     in WTOR messages IEE604D, IEE831D, and IEE088D. IBM
          recommends that you use the OK parameter only when
          issuing SLIP from a parmlib member.
    

Temporary fix

  • Customers can prevent experiencing this performance issue
    altogether, for both active and inactive SLIP PER traps,
    by avoiding specification of MODE=HOME without also
    specifying either JOBNAME or ASID. In other words, when
    using MODE=HOME, use JOBNAME or ASID as well.
    

Comments

APAR Information

  • APAR number

    OA45297

  • Reported component name

    SLIP/PER

  • Reported component ID

    5752SCSLP

  • Reported release

    790

  • Status

    CLOSED PER

  • PE

    NoPE

  • HIPER

    NoHIPER

  • Special Attention

    NoSpecatt / Xsystem

  • Submitted date

    2014-05-23

  • Closed date

    2014-08-20

  • Last modified date

    2014-10-02

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

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

    UA74641 UA74642

Modules/Macros

  • IEECB909 IEECB946 IEERTMEN IEERTMJP IGVDGNB
    IGVDGNTM
    

Publications Referenced
SA23138000SA38067400SA38066600  

Fix information

  • Fixed component name

    SLIP/PER

  • Fixed component ID

    5752SCSLP

Applicable component levels

  • R79J PSY UA74642

       UP14/09/10 P F409

  • R790 PSY UA74641

       UP14/09/10 P F409

Fix is available

  • Select the PTF appropriate for your component level. You will be required to sign in. Distribution on physical media is not available in all countries.

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Document Information

Modified date:
02 October 2014