IJ16663: PERFORMANCE DEGRADATION DUE TO CONTENTION IN READDIR & LOOKUP

APAR status

• Closed as program error.

Error description

• Fix for better fairness between directory ops threads
  that
  requires Fine grained directory locking  and the ones
  that
  requires block level locking. This will lead to better
  application response times for applications that requires
  both kinds of operations continuously. This will also
  lead
  to  better fairness between directory operations like
  lookups and readdirs.
  

Local fix

Problem summary

• Problem description:
  Poor readdir performance on a shared directory after workload
  caused local node to have lock on the entire directory.
  

Problem conclusion

• Benefits of the solution:
  Improve readdir performance on a shared directory for some
  workloads.
  
  Work Around:
  Avoid multiple "ls" on a shared directory.
  
  Problem trigger:
  Performing repeated readdir and lookup on a shared directory.
  
  Symptom:
  Performance Impact/Degradation
  
  Platforms affected:
  ALL Operating System environments
  
  Functional Area affected:
  All Scale Users
  
  Customer Impact:
  High Importance
  

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:

  IJ18144 IJ26948

Fix information

• Fixed component name

  SPEC SCALE ADV

• Fixed component ID

  5737F35AP

Applicable component levels