Figure 2-5. Sample instrumentation analysis code and the actual results focusing on the resources, rather than the modules. After repeated product runs, waiting for IO reads to complete is the overall performance-limiting factor.

There are a number of not so obvious yet extremely important advantages to this technique. First, a granular instrumentation will help developers focus on their code issues without being misled by other performance-limiting factors outside their control. In this example, the outside issue was IO reads. Second, nondevelopers can also use the detailed instrumentation to diagnose performance issues. While nondevelopers cannot change the source code, they can perhaps change parameters to influence code operation, such as how often and which code modules are being run, and they can influence the operating system on which the code is being run. Similarly, using Oracle's instrumentation benefits kernel developers, operating system administrators, and performance analysts.

Through Oracle's instrumentation efforts, Oracle kernel developers, Oracle performance analysts, and operating system administrators significantly benefit, as follows: