Debugging FPGA-accelerated Real-time Systems

The high computation/communication requirements along with reliability needs and limited power budgets necessitate complex processing platforms for emerging autonomous systems. Due to the current focus on performance, however, such platforms are increasingly difficult to predict and analyze. This holds true in terms of both performance (e.g., behavioral and temporal) aspects and power consumption. Ensuring functional safety thus requires new techniques to analyze performance, predictability and power. In this paper, we thus propose a novel hybrid tracing methodology to monitor (and, subsequently, optimize) temporal, functional and energy-related properties of Real-time Systems (RTSs). We target current Programmable SoCs (pSoCs) integrating a fixed-function System-on-Chip (SoC) with flexible Field Programmable Gate Array (FPGA) fabric. Although such heterogeneous systems are well suited for high-end, mixed-hardware/software real-time pipelines, they also offer more complex performance/energy trade-offs than software-only platforms. To systematically exploit this complexity, we present a resource-efficient trace IP core for the pSoC's fabric and an external measurement/interface system - jointly capturing hybrid power/state traces for subsequent (i.e., offline) analysis. By fusing state data from our IP core with events-of-interest gathered from power traces of pSoC and co-monitored I/O components, we gain a holistic view on temporal RTS aspects. Events and synchronized multi-rail power data jointly extend the debugging coverage via automated identification of processing phases, computation of energy baselines, and estimation of potential savings. Our solution thus integrates functional, temporal and energy monitoring into a single, unified workflow, which, in contrast to traditional separate tools, delivers valuable new insights helpful during debugging and reduces both cost and effort. Experimental evaluations on a Zynq-based Visual Servoing System show the method's various benefits.