OA46291: NEW FUNCTION - IMPROVE PERFORMANCE THROUGH IPTE AVOIDANCE

Obtain the fix for this APAR.

APAR status

• Closed as new function.

Error description

• New function
  

Local fix

Problem summary

• ****************************************************************
  * USERS AFFECTED: Users of JBB778H and up, running             *
  *                 on z13 compatible hardware                   *
  ****************************************************************
  * PROBLEM DESCRIPTION: Real storage management                 *
  *                      changes to reduce                       *
  *                      the number of IPTE                      *
  *                      instruction invocations                 *
  *                      on z13 hardware for improved            *
  *                      performance.                            *
  ****************************************************************
  * RECOMMENDATION:                                              *
  ****************************************************************
  The IPTE instruction is used to invalidate the
  virtual to real association when pages of storage
  are Freemained (Storage Released) or paged.  This
  instruction requires signalling all other processors
  within the system and does not scale well with
  the number of cpus on z13 hardware.  This apar
  is taken to reduce the number of IPTE instructions
  issued when pages of region private storage are
  Freemained.
  
  PTFs are provided at HBB7780, JBB778H, and HBB7790 but
  z13 support is only provided at JBB778H and HBB7790.
  The HBB7780 PTF is for compatibility with SRM.
  
  Additional Search Keywords:  R2964/K   D/T2964
  

Problem conclusion

Temporary fix

Comments

• The following changes are only in effect for z13 hardware.
  Consider the following changes to RAXFMCT, RCEAFC and
  TPROT before applying this new function.
  
  Under the direction of SRM, RSM Freemain processing
  is changed to maintain the virtual to real association
  of region private storage during Freemain processing.
  The address space that owns the pages being freed
  will continue to own the real storage associated
  with Freemained region storage after the Freemain
  invocation has completed.  In this case RAXFMCT, the count
  of frames owned by the address space will be higher than
  it was previously.  RCEAFC, the count of available
  frames owned by the system will be lower.
  The System Resource Manager will limit the
  number of "Freemained Frames" owned by the address
  space based on system conditions and how well the
  address space is making use of "Freemained Frames".
  To this end, RSM will track the getmain/freemain
  patterns of address spaces, recording the behavior.
  
  If the application references a page that is backed
  by a "Freemained Frame" it will not take an
  ABEND0C4 abend as it would previously.  The frame
  is cleared (or made dirty) before it is
  placed in this state to prevent any subsequent
  access of residual storage.
  
  If there is a large amount of "Freemained Frames"
  in the system and an attempt is made to configure
  storage offline while storage constrained, the
  offline configuration request may fail.  If
  reconfiguration is necessary, deactivation of
  "Freemained Frames" feature may be required.
  
  If an application issues the TPROT instruction
  passing a virtual address that is backed by a
  "Freemained Frame", it will not get a condition
  code of 3 as it would previously.  Applications
  that are using this instruction with region
  storage to determine whether the storage is getmained
  (storage obtained) should consider using VSMLOC instead.
  Applications that need to know whether the page
  is accessible and not backed by a "Freemained Frame" should
  consider using one of the following two new callable
  services, IARBRVER and IARBRVEA which are described
  in z/OS MVS Authorized Assembler Services Reference.
  
  This feature is active by default on z13 hardware.
  The DIAGxx parmlib member is modified to provide
  syntax to support deactivating the feature either
  system wide or within a set of address spaces.
  
  FREEMAINEDFRAMES(NO) indicates that the feature is
  disabled system wide.
  
  FREEMAINEDFRAMES(YES) EXCLUDEJOBLIST(Job1,Job2...Job8)
  indicates to exclude the feature from the list of
  up to 8 specified jobs.  Wildcarding of the jobnames with
  * and ? is supported and the * may appear in any
  position within the jobname.
  
  Issue the DISPLAY DIAG system command to verify that the
  system is using the requested FREEMAINEDFRAMES statement.
  
  Documentation updates for the above publications are located
  in a pdf file, OA46291.pdf, available at:
  - http://publibz.boulder.ibm.com/zoslib/pdf/OA46291.pdf
  ×**** PE15/07/01 PTF IN ERROR. SEE APAR OA48273  FOR DESCRIPTION
  ×**** PE15/08/14 FIX IN ERROR. SEE APAR OA48642  FOR DESCRIPTION
  ×**** PE15/10/19 FIX IN ERROR. SEE APAR OA49159  FOR DESCRIPTION
  ×**** PE16/02/04 FIX IN ERROR. SEE APAR OA49742  FOR DESCRIPTION
  

APAR Information

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

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

  UA90974 UA90975 UA90976

Modules/Macros

• IARHRF0I IARHRF15 IARRAX   IARRCE   IAXBR
  IAXCA    IAXCB    IAXCG    IAXCR    IAXCW    IAXDI    IAXGT
  IAXKB    IAXMA    IAXMP    IAXMR    IAXM2    IAXPF    IAXPO
  IAXPQ    IAXPZ    IAXP3    IAXQA    IAXQD    IAXRQ    IAXSA
  IAXUA    IAXUD    IAXUE    IAXUM    IAXUN    IAXUO    IAXUV
  IAXVF    IAXVG    IAXVP    IAXWT    IAXXS    IAXXT    IAXYG
  IAXYT    IAXZREAL IAXZREA2 IAXZSUM  IAXZTXTC IEECB975 IEFSMFIE
  IGVDGNB  IGVDGNXT IGVDIER1 IGVDIER2 IGVDILXA IGVDIMSG IGVDIPAR
  IGVDIPR  IGVGCAS  IGVTRCTL IHAPVT
  

Fix information

• Fixed component name

  RSM - REAL STOR

• Fixed component ID

  5752SC1CR

Applicable component levels

• R78H PSY UA90975

     UP15/06/10 P F506

• R780 PSY UA90974

     UP15/06/10 P F506

• R790 PSY UA90976

     UP15/06/10 P F506

Fix is available

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