PM65360: HIGH MSTR SRB CPU TIME IN DB2 V10

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• MSTR SRB time is increased a lot after migrating to V10.
  There's an internal growth of a storage cache, the management of
  that cache is causing MSTR CPU to be consumed.
  

Local fix

Problem summary

• ****************************************************************
  * USERS AFFECTED: All DB2 HDBAA10 V10 users.                   *
  ****************************************************************
  * PROBLEM DESCRIPTION: High DB2 MSTR SRB CPU time is observed  *
  *                      and some STATs fields not externalized  *
  *                      to IFCID1.                              *
  ****************************************************************
  * RECOMMENDATION: INSTALL PTF                                  *
  ****************************************************************
  During DB2 storage contraction, pool FREE or pool RESET of 64bit
  pools, high MSTR CPU time may be observed if the pool contains
  used blocks more than 8K in size.  This CPU increase may occur
  at commit or at thread deallocation or both, especially when the
  storage is contained in the CTV64STP or other thread pools
  which persist in cached threads beyond deallocation.
  While trying to analyze the reason for the CPU increase, it was
  observed that fields QSST_RSMAX_WARN, QSST_P64DISNUM,
  QSST_P64DISBLK, QSST_P64DISPGS, and QSST_CONTSTOR_NUM were
  missing from IFCID1.
  

Problem conclusion

• The logic for discarding the REAL frame backing for 64bit pools
  is changed to detect when blocks do not contain backed pages
  since the last time the discard was done.  This may occur
  during pool contraction or thread commit or deallocation.
  This avoids the IARV64 DISCARDDATA call to z/OS unless there
  are backed pages indicated.
  Also, the missing fields were externalized to the IFCID1.
  

Temporary fix

• *********
  * HIPER *
  *********
  

Comments

APAR Information

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

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

  UK80191

Modules/Macros

• DSNSCON2 DSNSQST  DSNSVSVP
  

Fix information

• Fixed component name

  DB2 OS/390 & Z/

• Fixed component ID

  5740XYR00

Applicable component levels

• RA10 PSY UK80191

     UP12/07/27 P F207

Fix is available

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