Sometimes when you trace things, you can discover some really interesting (and unexpected) stuff.
For example, here is a simple way to “freeze” your ORACLE database, which I “discovered” while tracing system calls in LGWR process (ORACLE 220.127.116.11 on Linux 2.6.18 ×64).
A very brief update.
One of the smaller (and nicer) part of ORA_MEM package is ora_cpu.pl utility that shows graphically what active db processes are doing at the moment … be it running SQL, accessing db object or waiting for something.
As an added benefit, it also shows some important OS statistics, such as process state or ‘spot’ CPU utilization for your database sessions.
This seems to be a rather odd exercise – why would you ever agree to have less memory on your system to run programs ?
But, of course it makes sense in a few special cases – testing how much memory your programs really need as well as validating how the system will behave if less memory is available (not every system is privileged to start with 32Gb+ of RAM).