PM14503: CLEARCASE MVFS ALLOCATES BETA SEMAPHORES INEFFICIENTLY FOR MNODE ALLOCATION ON HP-UX 11.31 IA SYSTEMS

APAR status

• Closed as program error.

Error description

• ClearCase MVFS allocates Beta Semaphores inefficiently for mnode
  allocation on HP-UX 11.31 IA systems
  
  
  ClearCase 7.0.1.3
  
  
  HP-UX 11.31 IA
  
  
  Problem Explained:
  
  Inefficient use of Beta Semaphores, when MVFS allocates mnodes,
  causes the lock class information hash table to increase in size
  with each new, unique mnode allocation.  As ClearCase is used,
  say within a build environment, the lock class information hash
  table increases exponentially: Subsequently, searching the hash
  table for entries becomes prohibitive, and the system
  performance begins to suffer.
  
  Workaround:  NONE
  

Local fix

Problem summary

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  * PROBLEM DESCRIPTION:                                         *
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  The issue is caused due to the way MVFS allocates locks
  (beta semaphores) to protect its internal data structures.
  While allocating the locks, MVFS associated every lock with
  a unique name. This was primarily to aid debugging of locks.
  On HP-UX 11.31 while initializing the beta semaphore, the
  kernel creates a data structure of its own using the
  parameters passed to the initialization routine. One of the
  parameters that is used is name of the lock. This data
  structure is maintained as a hash. No other platform
  (including HP-UX 11.23 or HP-UX 11.11) use the information
  passed to the initialization routine this way. Entries in
  the hash are flushed only when system is rebooted. With
  every lock allocation, the size of the hash increases, hence
  the time taken to allocate locks increases exponentially.
  

Problem conclusion

• A fix is available in ClearCase versions 7.0.1.10 and
  7.1.1.3
  

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

  CLEARCASE UNIX

• Fixed component ID

  5724G2901

Applicable component levels

• R701 PSN

     UP