The PVM 3 . 4 Tracing Facility and XPVM

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 latest release of PVM, Version 3.4, contains a new and improved tracing facility which provides more exible and eecient access to run-time program information. This new tracing system supports a buuer-ing mechanism to reduce intrusion, and a more exible trace event deenition scheme which is based more directly on SDDF (Self-Deening Data Format, Reed et al). This new scheme expedites the collection and analysis of execution histories, and allows for integration of custom trace events. The tracing instrumentation is built into the PVM library to avoid re-compilation, and supports on-they adjustments to each task's trace event mask, to control 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-deened events. The system has also been optimized to provide better real-time monitoring capabilities.