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 126.96.36.199 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.