Temporal Tracing of On-Chip Signals using Timeprints

This paper introduces a new method to trace cycle-accurately the temporal behavior of on-chip signals while operating in-field. Current cycle-accurate schemes incur unacceptable amounts of data for logging, storage and processing. Our key idea to enable efficient yet cycle-accurate tracing, is to bring timing to the front as a main traced artifact. We split the signal tracing into consecutive (back-to-back) finite trace-cycles. Within a trace-cycle, a signal's value-change instance gets assigned an encoded timestamp. At the end of each trace-cycle, these encoded timestamps are aggregated into a logged timeprint, which summarizes the temporal behavior over the trace-cycle. To retrieve the accurate timing, we reconstruct the exact instances from a timeprint via a SAT query. The experiments demonstrate how unprecedented lightweight tracing can be applied, and how timeprints enable the verification of cycle-accurate properties and the detection of sporadic temperature effects.