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.

The Linux trace command is strace. On Solaris, the command is truss. See your operating system documentation for its corresponding tracing command. When you issue the appropriate command for your operating system, the tracing immediately begins to spew forth output and continues until the process ends or you break out of the trace.

Figure 2-6 shows an Oracle Database 10g Release 1 server process operating system trace. The Oracle server process oracleprod3 has the process ID 14558. This is an active process, so many of lines in Figure 2-6 have been removed. Where the lines were removed, an ellipsis (...) was inserted.