On-Chip Monitoring for Non-Intrusive Hardware/Software Observability

The increased complexity in today’s state-of-the-art computer systems make them hard to analyse, test, and debug. Moreover, the advances in hardware technology give system designers enormous possibilities to explore hardware as a means to implement performance demanding functionality. We see examples of this trend in novel microprocessors, and Systems-on-Chip, that comprise reconfigurable logic allowing for hardware/software co-design. To succeed in developing computer systems based on these premises, it is paramount to have efficient design tools and methods.An important aspect in the development process is observability, i.e., the ability to observe the system’s behaviour at various levels of detail. These observations are required for many applications: when looking for design errors, during debugging, during performance assessments and fine-tuning of algorithms, for extraction of design data, and a lot more. In real-time systems, and computers that allow for concurrent process execution, the observability must be obtained without compromising the system’s functional and timing behaviour.In this thesis we propose a monitoring system that can be used for nonintrusive run-time observations of real-time and concurrent computer systems. The monitoring system, designated Multipurpose/Multiprocessor Application Monitor (MAMon), is based on a hardware probe unit (IPU) which is integrated with the observed system’s hardware. The IPU collects process-level events from a hardware Real-Time Kernel (RTK), without perturbing the system, and transfers the events to an external computer for analysis, debugging, and visualisation. Moreover, the MAMon concept also features hybrid monitoring for collection of more fine-grained information, such as program instructions and data flows.We describe MAMon’s architecture, the implementation of two hardware prototypes, and validation of the prototypes in different case-studies. The main conclusion is that process level events can be traced non-intrusively by integrating the IPU with a hardware RTK. Furthermore, the IPU’s small footprint makes it attractive for SoC designs, as it provides increased system observability at a low hardware cost.