The PVM 3.4 tracing facility and XPVM 1.1

One of the more bothersome aspects of developing a parallel program is that of monitoring the behavior of the program for debugging and performance tuning. This paper discusses an enhanced tracing facility and tracing tool for PVM (Parallel Virtual Machine), a message passing library for parallel processing in a heterogeneous environment. PVM supports mixed collections of workstation clusters, shared-memory multiprocessors, and MPPs. The upcoming release of PVM, Version 3.4, contains a new and improved tracing facility which provides more flexible and efficient access to run-time program information. This new tracing system supports a buffering mechanism to reduce the perturbation of user applications caused by tracing, and a more flexible trace event definition scheme which is based on a self-defining data format. The new scheme expedites the collection of program execution histories, and allows for integration of user-defined custom trace events. The tracing instrumentation is built into the PVM library, to avoid re-compilation when tracing is desired, and supports on-the-fly adjustments to each task´s trace event mask, for control over the level of tracing detail