IJ26697: NEED BRLOCK_AWAIT_REVOKE FLAG FOR ALL DIRECTORY RELATED BR TOKEN

APAR status

• Closed as program error.

Error description

• Customer is experiencing poor metadata performance
  
  From data collected, we have token starvation issue with
  regular RO BR token as well.   There are multiple threads
  doing readdir using regular RO token and they are
  preventing revoke from been processed. There are many
  lookup calls while these readdir threads are running and
  the lookup threads are blocking some of the readdir
  threads
  due to contention for buffer descriptor mutex on the
  directory block.
  

Local fix

Problem summary

• When multiple applications on a single node
  perform readdir and lookups on the same
  directory in a loop, it could lead to token
  starvation on other nodes trying to
  perform rename/create operation on the
  same directory.   This will show up as slow
  application performance on affected nodes.
  

Problem conclusion

• Benefits of the solution:
  Prevent token starvation due to repeated
  readdir/lookup on a directory so all nodes will
  have a fair share of access to a directory.
  Work Around: None
  Problem trigger:
  Running multiple application that repeatedly
  perform readdir/lookup (ls -l)
  on the same directory.
  * Symptom:
  Performance Impact/Degradation
  Platforms affected: All
  Functional Area affected: All
  Customer Impact: High
  

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:

  IJ27246

Fix information

• Fixed component name

  SPEC SCALE ADV

• Fixed component ID

  5737F35AP

Applicable component levels