It is very difficult to decide What to tune first? or from Where we need to start? Even well tuned database also shows a set of top wait events. The Oracle server provides a set of wait event statistics for processes that are idle or waiting. The Oracle server also records CPU utilization for processes that are running.
Request time consisting of Wait time (+) Service time(CPU time).
CPU Time : Time spent actively working on request.
Wait Time: Time spent on waiting for particular resource for some reason.
Both Service time and wait time may be tuned. To tune the Service time something has to change(processing, SQL, access path etc). Wait times can be tuned by reducing contention for the resource where the wait is occurring.
Each server process is typically in one of three states:
Idle : waiting for something to do(sleeping)
Running : Using the CPU or in run queue
Waiting : for some resource to become available or for a requested activity to complete.
So by examining CPU Time/Wait Time you can decide where is the problem, then you can dig into that area.
-Asifkhan P.
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