Application-Specific Tailoring of Multi-Core SoCs for Real-Time Systems with Diverse Predictability Demands
- 60 Downloads
Embedded multi-core processors improve performance significantly and are desirable in many application-fields. This development, in particular, includes safety-critical real-time systems, which typically require a deterministic temporal behavior. However, even tasks without dependencies running on different cores can interfere due to, sometimes hidden, shared hardware resources, such as memory or communication buses. Consequently, only a pessimistic assumption of the worst-case execution time (WCET) that incorporates interference can be given. The desired performance gain therefore evaporates in the poor temporal analyzability. Safety-critical real-time systems are typically composed of multiple tasks with varying criticality levels and requirements on predictability and performance, respectively. In this paper, we present an approach that generates an application-specific, deterministic multi-core architecture for such mix-critical systems, thus eliminating the aforementioned hardware-induced interferences in the first place. Safety-critical tasks with stringent temporal requirements are mapped to dedicated Deterministic Execution Units (DEUs) while the remaining soft real-time tasks co-reside on a general purpose multi-core processor that offers performance over determinism. Just as well, predictable interconnections between DEUs are generated to satisfy dependencies and precedence constraints. Consequently, timing analysis for hard real-time tasks is significantly simplified, since interferences caused by shared resources and scheduling are finally eliminated. To show the benefits of our approach, an application-specific architecture for a flight controller was generated and compared to an ARM Cortex-A9 dual-core as a reference. Overall, we were able to significantly improve temporal properties of safety-critical tasks while preserving the overall performance for soft real-time tasks.
KeywordsSafety-Critical Reconfigurable Reliable Deterministic Distributed NoC SoC
This work is supported by the German Research Foundation (DFG) under grants no. SCHR 603/9-2, the Transregional Collaborative Research Centre “Invasive Computing” (SFB/TR89, Project C1), the Bavarian Ministry of State for Economics under grant no. 0704/883 25 (EU EFRE funds) and by the Bavarian Research Foundation (BFS) as part of their research project “FORMUS3 IC”.
- 1.AbsInt aiT. https://www.absint.com/ait/.
- 2.APP4MC. http://www.eclipse.org/app4mc/.
- 3.Castrillon, J., Sheng, W., Jessenberger, R., Thiele, L., Schorr, L., Juurlink, B., Alvarez-Mesa, M., Pohl, A., Reyes, V., Leupers, R. (2015). Multi/many-core programming: where are we standing?. In 2015 design, automation test in Europe conference exhibition (DATE) (pp. 1708–1717). https://doi.org/10.7873/DATE.2015.1129.
- 4.Ferdinand, C., Heckmann, R., Wolff, H.J., Renz, C., Parshin, O., Wilhelm, R. (2008). Towards model-driven development of hard real-time systems. In Model-driven development of reliable automotive services (pp. 145–160). Springer.Google Scholar
- 5.Fernandez, G., Abella, J., Quiñones, E., Rochange, C., Vardanega, T., Cazorla, F.J. (2014). Contention in multicore hardware shared resources: understanding of the state of the art. In 14th international workshop on worst-case execution time analysis, OpenAccess Series in Informatics (OASIcs) (pp. 31–42): Schloss Dagstuhl–Leibniz-Zentrum für Informatik. https://doi.org/10.4230/OASIcs.WCET.2014.31. http://drops.dagstuhl.de/opus/volltexte/2014/4602
- 6.Fernández, M., Gioiosa, R., Quiñones, E., Fossati, L., Zulianello, M., Cazorla, F.J. (2012). Assessing the suitability of the NGMP multi-core processor in the space domain. In Proceedings of the tenth ACM international conference on embedded software, EMSOFT ’12 (pp. 175–184). New York: ACM. https://doi.org/10.1145/2380356.2380389. http://doi.acm.org/10.1145/2380356.2380389
- 7.Fürst, S. BMW_20151005.pdf. http://image.mdstec.com/mail/SES/BMW_20151005.pdf.
- 8.Kerrison, S., May, D., Eder, K. (2016). A Benes Based NoC switching architecture for mixed criticality embedded systems. In 2016 IEEE 10th international symposium on embedded multicore/many-core systems-on-chip (MCSOC) (pp. 125–132). https://doi.org/10.1109/MCSoC.2016.50
- 9.Lee, E., Reineke, J., Zimmer, M. (2017). Abstract PRET machines. In 2017 IEEE real-time systems symposium (RTSS) (pp. 1–11) . https://doi.org/10.1109/RTSS.2017.00041.
- 10.Liu, I., Reineke, J., Lee, E.A. (2010). A PRET architecture supporting concurrent programs with composable timing properties. In 2010 conference record of the forty fourth Asilomar conference on signals, systems and computers (pp. 2111–2115) https://doi.org/10.1109/ACSSC.2010.5757922.
- 11.Mollison, M.S., Erickson, J.P., Anderson, J.H., Baruah, S.K., Scoredos, J.A. (2010). Mixed-criticality real-time scheduling for multicore systems. In 2010 10th IEEE international conference on computer and information technology (pp. 1864–1871) https://doi.org/10.1109/CIT.2010.320
- 12.Montag, P., & Altmeyer, S. (2011). Precise WCET calculation in highly variant real-time systems (pp. 1–6). Design, Automation Test in Europe. https://doi.org/10.1109/DATE.2011.5763149
- 13.OSEK/VDX Group. (2005). Operating system specification 2.2.3. Tech. rep., OSEK/VDX Group. http://portal.osek-vdx.org/files/pdf/specs/os223.pdf, visited 2014-09-29.
- 14.Pfundt, B., Reichenbach, M., Hartmann, C., Häublein, K., Fey, D. (2016). Teaching heterogeneous computer architectures using smart camera systems. In 2016 11th European workshop on microelectronics education (EWME). https://doi.org/10.1109/EWME.2016.7496484.
- 15.Position Paper CAST-32A. https://www.faa.gov/aircraft/air_cert/design_approvals/air_software/cast/cast_papers/media/cast-32A.pdf. Certification Authorities Software Team (CAST).
- 17.Schreiner, S., Grüttner, K., Rosinger, S., Rettberg, A. (2014). Autonomous flight control meets custom payload processing: a mixed-critical avionics architecture approach for civilian UAVs. In IEEE 17th international symposium on object/component/service-oriented real-time distributed computing (pp. 348–357). https://doi.org/10.1109/ISORC.2014.28
- 18.Tobuschat, S., Axer, P., Ernst, R., Diemer, J. (2013). IDAMC: a NoC for mixed criticality systems. In 2013 IEEE 19th international conference on embedded and real-time computing systems and applications (pp. 149–156). https://doi.org/10.1109/RTCSA.2013.6732214
- 19.Ungerer, T., Cazorla, F., Sainrat, P., Bernat, G., Petrov, Z., Rochange, C., Quinones, E., Gerdes, M., Paolieri, M., Wolf, J., Casse, H., Uhrig, S., Guliashvili, I., Houston, M., Kluge, F., Metzlaff, S., Mische, J. (2010). Merasa: multicore execution of hard real-time applications supporting analyzability. IEEE Micro, 30(5), 66–75. https://doi.org/10.1109/MM.2010.78.CrossRefGoogle Scholar
- 20.Vaas, S., Reichenbach, M., Margull, U., Fey, D. (2016). The R2-D2 toolchain—automated porting of safety-critical applications to FPGAs. In 2016 international conference on reconfigurable computing and FPGAs (ReConFig). https://doi.org/10.1109/ReConFig.2016.7857192.
- 21.Vaas, S., Ulbrich, P., Reichenbach, M., Fey, D. (2017). The best of both: high-performance anc deterministic real-time executive by application-specific multi-core socs. In 2017 conference on design and architectures for signal and image processing (DASIP). https://doi.org/10.1109/DASIP.2017.8122107.
- 22.XMOS xCORE-200. Tech. rep. http://www.xmos.com/products/silicon/xcore-200.
- 23.Zimmer, M., Broman, D., Shaver, C., Lee, E.A. (2014). FlexPRET: a processor platform for mixed-criticality systems. In 2014 IEEE 19th real-time and embedded technology and applications symposium (RTAS) (pp. 101–110) . https://doi.org/10.1109/RTAS.2014.6925994