Event Tracing of pC++ Programs

In addition to profiling, we have implemented an extensive system for tracing pC++ program events. Currently, tracing pC++ programs is restricted to shared-memory computers (e.g., Sequent Symmetry, BBN Butterfly, and Kendall Square KSR-1) and the uniprocessor UNIX version. The implementation of the event tracing package to distributed memory machines is under way. Trace instrumentation support is similar to profiling. On top of the pC++ tracing system, we are implementing an integrated performance analysis and visualization environment. The performance results reported in this paper use utility tools to analyze the event traces that are based on externally available event trace analysis tools:

Merging:

Traced pC++ programs produce an event log for each node. The trace files will have names of the form <MachineId>.<NodeId>.trc. The single node traces must be merged into one global event trace, with all event records sorted by increasing timestamps. This is done with the tool se_merge. If the target machine does not have a hardware global clock, se_merge will establish a global time reference for the event traces by correcting timestamps.

Trace Conversion:

The utility tool se_convert converts traces to the SDDF format used with the Pablo performance analysis environment [21][18] or to ALOG format used in the Upshot event display tool [4]. It also can produce a simple user-readable ASCII dump of the binary trace.

Trace Analysis and Visualization:

The trace files can be processed with the SIMPLE event trace analysis environment or other tools based on the TDL/POET event trace interface [14][13]. These tools use the Trace Description Language (TDL) output of the Instrumentor to access the trace files. In addition, we have implemented a Upshot-like event and state display tool (offShoot) based on Tcl/Tk [16][15]. Like Upshot, it is based on the ALOG event trace format.