IV80574: REDUCED JIT PERFORMANCE FOR COMPUTATIONALLY BOUND WORKLOADS OPER ATING ON TIGHT LOOPS

APAR status

• Closed as program error.

Error description

• Error Message: N/A
  .
  Stack Trace: N/A
  .
  

Local fix

• -Xjit:disableAutoSIMD
  

Problem summary

• Under some circumstances the JIT optimizer can produce a
  non-ideal code sequence when optimizing computationally bound
  workloads based on tight loops composed of disjoint linear array
  reads and writes in combination with arithmetic operations. The
  JIT attempts to use hardware vector instructions to accelerate
  these loops on POWER and Z platforms, but under some
  circumstances the overhead of vector execution is prohibitive."
  

Problem conclusion

• JIT has been enhanced to better handle small computationally
  bound workloads and generates vector instructions only when they
  are likely to improve loop performance or some such
  .
  This APAR will be fixed in the following Java Releases:
     8    SR2 FP10  (8.0.2.10)
  .
  Contact your IBM Product's Service Team for these Service
  Refreshes and Fix Packs.
  For those running stand-alone, information about the available
  Service Refreshes and Fix Packs can be found at:
             https://www.ibm.com/developerworks/java/jdk/
  

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:

Fix information

• Fixed component name

  JIT

• Fixed component ID

  620700124

Applicable component levels

• R130 PSY

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