Summary
On HP-UX Itanium Superdome after the upgrade to 10.2.0.4 Oracle automatically stopped using all the cells and from
5 cells uses only the first cell. That had as a result from the 40 cpus of the server, oracle to uses only the first 8.
The
upgrade to Oracle 10.2.0.4 automatically changed the initialization parameters to:
_enable_numa_optimization=TRUE
_db_block_numa=5
You can check this specific hidden parameters with the query
SELECT * FROM (
SELECT a.ksppinm AS parameter,
a.ksppdesc AS description,
b.ksppstvl AS session_value,
c.ksppstvl AS instance_value
FROM x$ksppi a,
x$ksppcv b,
x$ksppsv c
WHERE a.indx = b.indx
AND a.indx = c.indx
AND a.ksppinm LIKE '/_%' ESCAPE '/'
ORDER BY a.ksppinm)
WHERE parameter IN ('_enable_NUMA_optimization', '_db_block_numa')
PARAMETER DESCRIPTION SESSION_VALUE INSTANCE_VALUE
---------------------------------------- ---------------------------------------- -------------- ---
_db_block_numa Number of NUMA nodes 1 1
_enable_NUMA_optimization Enable NUMA specific optimizations FALSE FALSE
Workaround
Change the hidden parameters to the following values and restart the database
alter system set "_enable_NUMA_optimization" = FALSE scope = spfile;
alter system set "_db_block_numa" = 1 scope = spfile;
Related information can be found in Metalink:
Doc ID: 760705.1
Oracle Background Processes (Including Parallel Processes) Using Only First 8 CPUs (Half) on 16-CPU Server
Doc ID: 7171446.8
Bug 7171446 - NUMA enabled by default can cause high CPU / OERI
Other related errors to alert.log
ORA-07445:[$PXNMOVE] and ORA-07445:[$COLD_KKERFP()+1984].
Other links
ORA-00600: [kskreconfignuma2], [kskcpucc]
