There is no problem in allocating more swap if the processes need it. swap is allocated in 2 ways: reserved and actual. reserved swap may never be used but the OS needs the space just in case. As far as performance, as long as vmstat reports single digit numbers for po (page out) most of the time, you're just fine. Oracle doesn't allocate RAM--DBAs allocate RAM. They do it in several ways. The largest space by far is SGA, the Oracle shared memory area and in general more is better, assuming the DBAs are using the ewxtra space effectively (local temp sort areas, row insertion space, disk buffering, etc).
Now shared memory (SGA) is separate for each Oracle instance, and ipcs -bmop will show these spaces. Individual programs and threads will grab memory based on config parameters. CPU usage is somewhat of an indication of effective use of RAM. The whole purpose of large RAM is to avoid disk accesses by either caching needed data, or using the shared area instead of disk I/O.
But unbalanced indexes (or missing indexes) will generate partial or full searches, essentially reading the entire database for needed records. More RAM won't help--adding or balancing indexes will help enormously. This is what the DBA gets paid to do: read all the Oracle performance tuning docs and measuring long SQL procedures to see what is causing the delays. Of course, a massive load on the system may max out both disk and CPU in which case, capacity planning kicks into play and you look at a larger machine.
Bill Hassell, sysadmin
