Existing kernel-level debugging primitives are inappropriate for instrumenting complex sequential or parallel programs. These functions incur a heavy overhead in their use of system calls and process switches. Context switches are used to alternately invoke the debugger and the target programs. System calls are used to communicate data between the target and debugger.

Existing debuggers and profilers are inadequate for debugging and profiling parallel programs. They are awkward in their handling of multiple threads of control and highly intrusive in their monitoring of program behavior. ParasightTM is an architecture that is geared towards non-intrusive high-level debugging and profiling. Parasight controls and observes the execution of parallel programs in terms of the set of abstractions that are being employed by the programmer. Different sets of abstractions can be implemented and applied to the same target program to extract different kinds of information. These abstractions are implemented as separate programs that are linked dynamically to the target program by Parasight. This paper describes our experience in implementing and using Parasight on the Encore Multimax,TM a shared-memory multiprocessor running UNIXTM. It has been used successfully in debugging and monitoring the performance of a computer architecture simulator, a complex parallel program.

This paper concerns the performance evaluation of an operating system based on communicating processes. Processes communicate via messages and there is no shared data.