Large Pages Information had been changed in the Oracle Database 12c Alert Log

Applies to:

Oracle Database - Enterprise Edition - Version 12.1.0.2 and later
Oracle Database Cloud Schema Service - Version N/A and later
Oracle Database Exadata Express Cloud Service - Version N/A and later
Oracle Database Exadata Cloud Machine - Version N/A and later
Oracle Cloud Infrastructure - Database Service - Version N/A and later
Information in this document applies to any platform.

Goal

Large Pages Information in the Alert Log
 

Solution

In 11.2 the alert log is populated with messages like:

Tue Feb 10 15:40:58 2015
Starting ORACLE instance (normal)
************************ Large Pages Information *******************
Per process system memlock (soft) limit = 48 GB

Total Shared Global Region in Large Pages = 1026 MB (100%)

Large Pages used by this instance: 513 (1026 MB)
Large Pages unused system wide = 1 (2048 KB)
Large Pages configured system wide = 514 (1028 MB)
Large Page size = 2048 KB
********************************************************************

In 12c message had been changed to:

**********************************************************************
Tue Feb 10 15:26:02 2015
Dump of system resources acquired for SHARED GLOBAL AREA (SGA)

Tue Feb 10 15:26:02 2015
 Per process system memlock (soft) limit = 48G
Tue Feb 10 15:26:02 2015
 Expected per process system memlock (soft) limit to lock
 SHARED GLOBAL AREA (SGA) into memory: 1026M
Tue Feb 10 15:26:02 2015
 Available system pagesizes:
  4K, 2048K
Tue Feb 10 15:26:02 2015
 Supported system pagesize(s):
Tue Feb 10 15:26:02 2015
  PAGESIZE  AVAILABLE_PAGES  EXPECTED_PAGES  ALLOCATED_PAGES  ERROR(s)
Tue Feb 10 15:26:02 2015
        4K       Configured               5               5        NONE
Tue Feb 10 15:26:02 2015
     2048K              514             513             513        NONE
Tue Feb 10 15:26:02 2015
**********************************************************************

 

Note:  In 12c, on AIX platforms, because of Bug 21095582 - 12.1 ALERT LOG DOES NOT SHOW LARGE PAGES USAGE IN AIX (currently in 11)  the large pages information is not present.

Large pages are actually used BUT not reported in alert log file where only 4K pages are mentioned as we can see from the below example:

Available system pagesizes:
 4K
Thu May 07 17:58:52 2015
Supported system pagesize(s):
Thu May 07 17:58:52 2015
 PAGESIZE  AVAILABLE_PAGES  EXPECTED_PAGES  ALLOCATED_PAGES  ERROR(s)
Thu May 07 17:58:52 2015
       4K       Configured          524291          524291        NONE

==> No 16M page information is shown even it is used by the instance.

References

NOTE:1392543.1 - Large Pages Information in the Alert Log
NOTE:361468.1 - HugePages on Oracle Linux 64-bit
NOTE:401749.1 - Oracle Linux: Shell Script to Calculate Values Recommended Linux HugePages / HugeTLB Configuration