IZ25650: LOAD PERFORMANCE PROBLEM ON WINDOWS IF THE CPU PARALLELISM APPLIED IS GREATER THAN 1

APAR status

• Closed as program error.

Error description

• When load cpu_parallelism > 1 is applied on load on the Windows
  platform ( which is the default with a sufficiently sized
  UTIL_HEAP_SZ and a multi CPU machine ), it is possible that
  the load may not have optimal performance.
  
  This is due to a particular spinlock algorithm applied by the
  formatter processes in a load that may suffer from thread
  starvation by the Windows process scheduler.
  
  The problem can be diagnosed with the output of a db2trc
  -perfcount -t data collection, showing excessive wait times in
  the sqlulPutBuffer function call.
  

Local fix

• In some cases the Windows scheduler behaves differently when
  other single process/ multi threaded applications e.g. the
  javaw.exe process started by the Control Center is started. This
  then appears to avoid the thread starvation in the load agents.
  

Problem summary

• ****************************************************************
  * USERS AFFECTED:                                              *
  * Windows users only with multi CPU machines                   *
  ****************************************************************
  * PROBLEM DESCRIPTION:                                         *
  * db2 load performance problem.When load cpu_parallelism > 1   *
  * is applied on load on theWindowsplatform ( which is the      *
  * default with a sufficiently sizedUTIL_HEAP_SZ and a multi    *
  * CPU machine ), it is possible thatthe load may not have      *
  * optimal performance.This is due to a particular spinlock     *
  * algorithm applied bytheformatter processes in a load that    *
  * may suffer from threadstarvation by the Windows process      *
  * scheduler.The problem can be diagnosed with the output of a  *
  * db2trc-perfcount -t data collection, showing excessive wait  *
  * timesinthe sqlulPutBuffer function call.                     *
  ****************************************************************
  * RECOMMENDATION:                                              *
  * Upgrade the server side to fixpak 18                         *
  ****************************************************************
  Parallel Load performance problem on Multi CPU windows.
  

Problem conclusion

• This problem was first fixed in v8.2 fixpak 18
  

Temporary fix

Comments

APAR Information

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

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

  IZ35534 IZ35535

Fix information

• Fixed component name

  DB2 UDB ESE SOL

• Fixed component ID

  5765F4102

Applicable component levels

• R820 PSN

     UP