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In this best practice, we used an Oracle undocumented parameter _high_priority_processes to improve database performance. This parameter gices the LGWR process a higher CPU priority. We recommend that customers check with Oracle Support before using this parameter in production. For more information, see the Oracle support document: Doc ID 1373500.1.
Overview
The Oracle hidden parameter “_high_priority_processes” enables the database administrator to assign priority to database processes. The following is the default value of the parameter:
_high_priority_processess = ’LMS*|LM1*|LM2*|LM3*|LM4*|LM5*|LM6*|LM7*|LM8*|LM9*’
The LMSn and LMn process relates to the global cache service process. These processes receive, process, and send requests for the global cache service and the buffer cache resources.
To optimize the database configuration, we configured the parameter to prioritize these processes:
_high_priority_processess = ’LMS*|VKTM|LGWR’
Changing the _high_priority_processess parameter requires a database instance restart.
Implementation Steps
Perform the following script.
SQL> ALTER SYSTEM SET “_high_priority_processess”=’LMS*|VKTM|LGWR’ SCOPE=SPFILE;
Restart the database instance.
Check the current value of this parameter, run this query as sys or system user.
SQL> select x.ksppinm name, x.ksppdesc description, y.ksppstvl value
from sys.x$ksppi x, sys.x$ksppcv y
where 1=1 and x.inst_id = y.inst_id and x.indx = y.indx
and x.ksppinm ='_high_priority_processes’;
Recommendation
Results from validating the best practices of the Linux operating system and Oracle database showed a significant performance improvement. Test findings showed increases in:
Oracle metrics that showed improvement are:
Based on the results, these best practices are considered as Day 1, Highly Recommended.