DTrace computes and reports program stability attributes. Ideally, you might like to construct DTrace programs by consuming only Stable or Evolving interfaces. However, when debugging a low-level problem or measuring system performance, you might need to enable probes that are associated with internal operating system routines such as functions in the kernel, rather than probes associated with more stable interfaces such as system calls. The data available at probe locations deep within the software stack is often a collection of implementation artifacts rather than more stable data structures such as those associated with the Oracle Solaris system call interfaces. In order to aid you in writing stable D programs, DTrace provides a facility to translate implementation artifacts into stable data structures accessible from your D program statements.
This chapter contains the following topics: