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VM66063: HIGH PR/SM LPAR MANAGEMENT TIME

A fix is available

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APAR status

  • Closed as unreproducible in next release.

Error description

  • When the LPARs of the CPC have substantial numbers of
    vertical-low logical cores, LPAR management time is excessive
    in some workloads. Performance Toolkit report FCX302 PHYSLOG
    column %LPmgt reports PR/SM LPAR management time. This is the
    amount of CPU time used by the PR/SM hypervisor for its own
    purposes, that is, it's PR/SM CPU time not chargeable to any
    LPAR. This can especially happen when the LPARs of the CPC are
    running vertically and have substantially more logical cores
    than their entitlements can cover, in other words, when the
    LPARs have substantial numbers of vertical-low logical cores.
    

Local fix

  • N/A
    

Problem summary

  • ****************************************************************
    * USERS AFFECTED: 1. Customers whose LPARs have more than one  *
    *                    or two vertical-low logical cores per     *
    *                    LPAR                                      *
    *                 2. Customers experiencing high FCX302        *
    *                    PHYSLOG %LPmgt.                           *
    *                 3. Customers experiencing high FCX304 PRCLOG *
    *                    %Susp.                                    *
    *                 4. Customers experiencing high FCX304 PRCLOG *
    *                    Syst.                                     *
    *                 5. Customers experiencing high FCX239        *
    *                    PROCSUM Diag9C.                           *
    *                 6. Customers experiencing high FCX104 PRIVOP *
    *                    Diagnose X'9C'.                           *
    ****************************************************************
    * PROBLEM DESCRIPTION:                                         *
    ****************************************************************
    * RECOMMENDATION: APPLY PTF                                    *
    ****************************************************************
     When Global Performance Data (GPD) is on, z/VM decides the
    unparked configuration based on projected capacity. When this
    decision leads to en mass unparking of vertical-low logical
    cores it can tend to promote Processor Resource/Systems Manager
    (PR/SM) dispatch contention.
    

Problem conclusion

Temporary fix

  • FOR RELEASE VM/ESA CP/ESA R640 :
    PREREQ: VM65988 VM65942
    CO-REQ: NONE
    IF-REQ: NONE
    

Comments

  • One factor that can cause high PR/SM LPAR management time is
    running with too many vertical-low logical cores unparked.
    Running in such a fashion creates dispatch contention in the
    PR/SM hypervisor and thereby contributes to high LPAR management
    time.
    
    This APAR provides support for new unparking heuristics that can
    help to reduce the number of unparked vertical-low logical
    cores. To offer relief APAR VM66063 provides two additional
    unparking heuristics for the case where GPD is on. New support
    in the command CP SET SRM selects the unparking heuristic to be
    used. The three GPD-on heuristics are now LARGE, MEDIUM, and
    SMALL. For more information, refer to this article:
    http://www.vm.ibm.com/perf/tips/unpark.html
    

APAR Information

  • APAR number

    VM66063

  • Reported component name

    VM CP

  • Reported component ID

    568411202

  • Reported release

    640

  • Status

    CLOSED UR1

  • PE

    NoPE

  • HIPER

    NoHIPER

  • Special Attention

    YesSpecatt / New Function / Xsystem

  • Submitted date

    2017-08-18

  • Closed date

    2017-10-27

  • Last modified date

    2018-12-14

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

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

    UM35231 UM35232

Modules/Macros

  • HCPHIC   HCPMES   HCPMESA  HCPMESB  HCPMNE   HCPMTE   HCPMXRBK
    HCPSCFBK HCPSRM   HCPSRXBK HCPSYS   HCPSYSCM HCPWHI   HCPZPQ
    HCPZSC   MRPRCPUP MRSCLSRM SRM
    

Publications Referenced
SC24617812 SC24617511      

Fix information

  • Fixed component name

    VM CP

  • Fixed component ID

    568411202

Applicable component levels

  • RA64 PSY UM34768

       UP18/12/14 P 1802  

  • R640 PSY UM35232

       UP17/11/09 P 1802  

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.



Document information

More support for: z/VM family

Software version: 640

Operating system(s): z/VM

Reference #: VM66063

Modified date: 14 December 2018