Composing Time- and Event-driven Distributed Real-time Systems Gabor Madl (gabe@ics.uci.edu), Ph.D. Candidate, UC Irvine Advisor: Nikil Dutt (dutt@ics.uci.edu) Chancellor’s Professor, UC Irvine Cyber-Physical System Challenges in the Automotive Domain, RTSS 2007 November 11, 2018

Challenges in NGAS November 11, 2018 Challenges Traditional Design Compose Functionalities Combine Analysis Model-based Analysis Challenges in NGAS How to safely increase functionality? Primary concern is safety (at least it should be) Secondary concern is cost (?) Increase functionality while constraints above are preserved How would a painter work under these conditions? Pietr Mondrian, Composition No. 10, 1939-42 Hans Hofmann, The Gate, 1959-60 Kazimir Malevich, Black Square, 1915 November 11, 2018

Separate Functionalities Challenges Traditional Design Compose Functionalities Combine Analysis Model-based Analysis Separate Functionalities Dedicated hardware for each functionality “Protect” components from each other Design them independently Are we sure that there is no interaction between critical and non-critical functionalities? Leakage power: drains power even when the car is idle Energy consumption: could become a bottleneck How will critical functionalities perform in a resource-constrained environment? Suboptimal utilization More components are needed Limited interaction with the environment November 11, 2018

Rethink Design of NGAS November 11, 2018 Challenges Traditional Design Compose Functionalities Combine Analysis Model-based Analysis Rethink Design of NGAS We need to use more flexible design methodologies than the current practice We need to learn to better utilize the potential of distributed real-time embedded (DRE) systems More and more sensors and actuators More interaction between components and their environment We need to build on the strengths of existing design methodologies, but also encourage interaction Cars could use information from the environment (i.e. weather information, GPS, other cars) to prepare for unforeseen circumstances, such as fog, freezing, accidents ahead etc. Non-critical functionality could be used as “backup” to increase fault tolerance November 11, 2018

Compose Functionalies Challenges Traditional Design Compose Functionalities Combine Analysis Model-based Analysis Compose Functionalies Critical functionalities Time-triggered systems Focus on control (scheduling) Execution times, periods, deadlines, priorities, etc. Mathematical model for analysis (scheduling theory) Simple analysis, costly implementation Non-critical functionalities Event-driven systems Focus on the flow of data Throughput, communication architecture, parallelization, etc. Complex model, hard to predict all behaviors Simple implementation, costly analysis November 11, 2018

Need to Combine Analysis Methods Challenges Traditional Design Compose Functionalities Combine Analysis Model-based Analysis Need to Combine Analysis Methods Static analysis methods Often too abstract, resulting in conservative/inaccurate results Cannot capture dynamic effects Simulations Can show the presence of an error, never its absence Ad-hoc, hard to measure coverage Limited design space exploration Model checking State space explosion problem No partial results Time consuming and costly Each method has its advantage and disadvantage November 11, 2018

Model-based Design & Analysis Challenges Traditional Design Compose Functionalities Combine Analysis Model-based Analysis Model-based Design & Analysis Model-based design provides the means for the early exploration of design alternatives The design flow is driven by the DSM, a high-level specification that captures key properties Mappings play a key role in abstraction Formal models drive functional verification We propose the combination of simulations and formal methods for the evaluation of designs November 11, 2018

Questions? November 11, 2018 Links to relevant work: http://dre.sourceforge.net http://alderis.ics.uci.edu http://www.ics.uci.edu/~gabe Cyber-Physical System Challenges in the Automotive Domain, RTSS 2007 November 11, 2018