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. Often there is no intrinsic support for examining program state and dynamics in a parallel programming system, let alone a useful interface for analyzing or visualizing that information. 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. Along with this new tracing facility, the graphical console and monitor XPVM has been updated to provide better access to the new tracing functionality. Several new views have been implemented to utilize the additional tracing information now possible, including user-defined events. The XPVM system has also been optimized to provide better real-time monitoring capabilities. *Research supported by the Applied Mathematical Sciences Research Program of the Office of Energy Research, U.S. Department of Energy, under contract DEAC05-840R21400 with Lockheed Martin Energy Systems, Inc.