VM66063: HIGH PR/SM LPAR MANAGEMENT TIME

Obtain the fix for this APAR.

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 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
  

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.