Sure, it's a lot of fun to figure out the response time to the minutia level, and it definitely is good for your image and makes great cocktail party conversations, but the value of this missing time is highly questionable. During a firefight, it's easy to get distracted from the main overriding goal, and trying to account for every microsecond can cause the technical problem solver to stray from the main objective.

Understanding how Oracle collects time is not only fascinating, but it also gives you a greater appreciation for the Oracle wait interface. You'll have a better idea of how the wait interface works, which provides you with a higher level of confidence during analysis and when presenting your results. You will also begin to use the instrumentation in creative and highly effective ways.

We must get creative to see how Oracle instruments its kernel code. Since we are not Oracle kernel developers, we obviously do not have access to Oracle's kernel code. But all is not lost! By tracing an Oracle process through the operating system, we can easily observe how Oracle has instrumented it code. The depth of knowledge you gain from doing this yourself is amazing.