IC90889: ADDITION OF SHARED MEMORY SEGMENTS USING LARGE PAGES CAN BE SLOW AND MAY BLOCK USER ACTIVITY

APAR status

• Closed as program error.

Error description

• When the environment variable IFX_LARGE_PAGES is defined
  together with the RESIDENT onconfig parameter to enable the
  large memory pages feature, the creation of shared memory
  segments is generally a fast activity due to the lower OS
  resource overhead. When additional segments are required,
  following startup of the IDS server, they should also be added
  using the large pages feature. However the ability to use large
  pages is dependent both on the OS platform and the method by
  which the new segment is added. When using the onmode -a command
  to manually add a segment the operation should be fast. When the
  segment is added automatically due to the memory requirements of
  a thread then there may be problems:
  
  - On Linux it may not be possible to add the new segment.
  Versions of IDS with a fix for APAR IC86077 will fallback to
  using normal pages.
  - On AIX the request to create the new segment will not use
  large pages due to insufficient privileges of the oninit
  process. The OS will allocate the shared memory using a standard
  page size which for large segment sizes can take some time. For
  example:
  
  14:42:45  Requested shared memory segment size rounded from
  30000000KB to 30146560KB
  14:42:45  Shared memory segment will use large pages if
  available.
  14:43:39  Dynamically allocated new virtual shared memory
  segment (size 30146560KB)
  14:43:39  Memory sizes:resident:67108864 KB, virtual:214172736
  KB, no SHMTOTAL limit
  
  The operation to create the new segment took 54 seconds during
  which time requests to allocate or release memory may be
  blocked. This can delay user activity.
  

Local fix

• On AIX the delay of adding new segments may be reduced by using
  a 64 KB page size for shared memory pages instead of the default
  4 KB. This may be achieved by setting the environment variable
  LDR_CNTRL="SHMPSIZE=64K" prior to starting oninit.
  

Problem summary

• ****************************************************************
  * USERS AFFECTED:                                              *
  * All Users,                                                   *
  ****************************************************************
  * PROBLEM DESCRIPTION:                                         *
  * See Error Description                                        *
  ****************************************************************
  * RECOMMENDATION:                                              *
  * Update to IDS-11.70.xC8                                      *
  ****************************************************************
  

Problem conclusion

• Problem Fixed In IDS-11.70.xC8
  

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

  INFORMIX SERVER

• Fixed component ID

  5725A3900

Applicable component levels

• RB70 PSY

     UP

• RC10 PSY

     UP