VM66195: QUERY MT INITIAL CAN CAUSE SYSTEM HANG

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• System hangs when Query MT INITIAL command is issued when the
  MULTITHREADING statement requests 2 threads for non-IFL cores.
  The HMC shows that the LPAR is operating and one processor at
  high processor utilization.
  Query MT itself works fine, only Q MT INIT causes this behavior.
  
  This occurs when Multithreading is enabled in the SYSTEM
  CONFIG file and the number of threads for non-IFL processors is
  greater than the system supported number, currently = 1.
  Such as:  MULTITHREADING ENABLE TYPE ALL 2
            MULTITHREADING ENABLE TYPE CP 2 TYPE ICF 2 TYPE ZIIP 2
  

Local fix

• On the Multithreading statement in SYSTEM CONFIG, specify the
  number of threads for TYPE ALL as MAX or if the TYPES: CP, ICF,
  or ZIIP are specified separately they can be specified as 1.
  If running with IFL's only specify TYPE IFL 2.
  

Problem summary

• ****************************************************************
  * USERS AFFECTED: ALL USERS OF MULTITHREADING                  *
  ****************************************************************
  * PROBLEM DESCRIPTION:                                         *
  ****************************************************************
  * RECOMMENDATION: APPLY PTF                                    *
  ****************************************************************
  System hangs when Query MT INITIAL command is issued when the
  MULTITHREADING statement requests 2 threads for non-IFL cores.
  The HMC shows that the LPAR is operating and one processor at
  high processor utilization.
  Query MT itself works fine, only Q MT INIT causes this behavior.
  
  This occurs when Multithreading is enabled in the SYSTEM CONFIG
  file and the number of threads for non-IFL processors is greater
  than the system supported number, currently = 1.
  Such as:  MULTITHREADING ENABLE TYPE ALL 2
            MULTITHREADING ENABLE TYPE CP 2 TYPE ICF 2 TYPE ZIIP 2
  
  In HCPMTF, subroutine QYPREP, there is a bad branch causing an
  infinite loop.
  At label QYPSYLOW when the requested value is higher than the
  hardware or system max, a BRL QYPSYLOW is done.  This causes
  us to branch back but we don't change the values in the
  registers being compared.
  

Problem conclusion

• The branch has been changed to BRL QYPSTORE, which allows us
  to set the activated count and continue.
  

Temporary fix

• *********
  * HIPER *
  *********
  FOR RELEASE VM/ESA CP/ESA R640 :
  PREREQ: NONE
  CO-REQ: NONE
  IF-REQ: NONE
  FOR RELEASE VM/ESA CP/ESA R710 :
  PREREQ: NONE
  CO-REQ: NONE
  IF-REQ: NONE
  

Comments

APAR Information

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

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

  UM35359 UM35360

Modules/Macros

• HCPMTF
  

Fix information

• Fixed component name

  VM CP

• Fixed component ID

  568411202

Applicable component levels

• R640 PSY UM35359

     UP18/10/03 P 1901 ¢

• R710 PSY UM35360

     UP18/10/03 P 1901 ¢

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.