VM66333: PEVM66271 ABENDSXA004 DURING VERY HEAVY PAGING LOAD 22/01/10 PTF PECHANGE

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• Under very heavy Paging loads z/VM takes a SXA004 ABEND (System
  execution space pages have been exhausted.)
  This is more likely to occur with SCSI paging.
  

Local fix

Problem summary

• ****************************************************************
  * USERS AFFECTED: All users of z/VM.                           *
  ****************************************************************
  * PROBLEM DESCRIPTION:                                         *
  ****************************************************************
  * RECOMMENDATION: APPLY PTF                                    *
  ****************************************************************
  Under very heavy Paging loads z/VM took an SXA004 ABEND (System
  execution space pages have been exhausted.)  This occured after
  a large Deferred PGMBK Paging List (DPPL) had been accumulating
  and the system began paging.  Every time demand scan is called,
  DPPL processing is kicked off.  With VM66271, even if there is
  no contiguous frames demand, a bare minimum of the DPPL is
  processed.  Due to the heavy paging, this minimum amount was
  done over and over again consuming resources needed in order to
  do I/O with out giving the paging subsystem time to catch up.
  This results in the SXS004 Abend.
  

Problem conclusion

• With VM66271 HCPHRU may decide to do a minimum amount of DPPL
  processing when there is no contiguous frame demand.  Code was
  added to not process additional PGMBKs if there is no need, and
  already outstanding PGMBK writes.  This will allow the paging
  subsystem to finish when the only reason for the I/O in the
  first place was to do a minimum amount.
  

Temporary fix

• *********
  * HIPER *
  *********
  FOR RELEASE VM/ESA CP/ESA R720 :
  PREREQ: VM66271 VM66173
  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:

  UM35836

Modules/Macros

• HCPHRU
  

Fix information

• Fixed component name

  VM CP CP

• Fixed component ID

  568411202

Applicable component levels

• R720 PSY UM35836

     UP22/01/26 P 2201 ­

Fix is available

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