Stupid Oracle vktm tricks to improve VirtualBox performance



In the process of creating a demo VirtualBox image running OEL 6 and the Oracle database 11.2.0.3.0 I noticed the idle CPU consumption was quite high (8% on the guest, 35% on the host).

The culprit turned out to be the Oracle database vktm process. This is a time keeping process - and it calls gettimeofday() *very* frequently.  This can have a negative performance impact in virtualized environments.

A colleague who is a database whiz suggested the following trick:


sqlplus / as sysdba
alter system set "_high_priority_processes"='LMS*' scope=spfile; 

This removes the vktm process from the list of high priority processes.

After this change (you need to bounce the database) the idle CPU consumption comes down to 1-2% or so. A nice improvement!

It goes without saying that this is:

a) Totally unsupported
b) Probably dangerous. This will most certainly break things in the database - such as statistics, auditing, etc.
c) For demo/development use only. If you care about your data don't do this!

YMMV.


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