All Linux/Unix systems contain the /proc virtual file system, which offers a staggering amount of information about operating system activity: CPU, memory, device and IO activity, process-level information, and even CPU chip details. It's amazing what you can find. For most DBA types, /proc represents a whole new world to explore! On Linux, all the /proc files are in text, and they can be easily retrieved and parsed to create your own reports. Unfortunately, on other platforms, such as HP-UX and Solaris, the /proc files are binary, and you'll need to do some work, such as write a C program, to retrieve the details.

Figure 4-9 shows an example of the /proc/stat file. The first line, which begins with cpu, contains all the CPU time components since the system last booted. Figure 4-10 makes use of this information to create a real, and arguably useful, average CPU utilization report. A sample run output is shown in Figure 4-11.3

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