Multicore platforms have the potential of revolutionizing the capabilities of embedded cyber-physical systems. Unfortunately, when such systems have safety-critical components, multicore platforms are rarely used. The reason is a lack of predictability associated with hardware components such as caches, memory controllers, etc., that are shared among cores. Safety-critical systems require certification; with current technology, very conservative estimates concerning the usage of these shared resources must be made, to certify that overuse violations do not occur at runtime. The resulting over-provisioning can be significant, easily negating the processing power of any additional cores.
In this project, research will be conducted to resolve this multicore "predictability problem." A key focus of the project will be the development of methods that enable shared hardware resources to be allocated in a predictable way. Additionally, implementations of these methods will be produced within real-time operating systems (RTOSs) or middleware, and associated tools will be produced for provisioning and analyzing systems. The devised methods will be evaluated through experimental research involving synthetic micro-benchmarks and through work on a difficult challenge problem: the development of a real-time resource allocation framework for next-generation unmanned air vehicles (UAVs). In comparison to current UAVs, these future UAVs will have far greater autonomous capabilities and will be significantly better equipped to adapt to changing environmental conditions.
Addressing the "predictability problem" associated with multicore platforms would be a breakthrough result for safety-critical, cyber-physical systems in domains such as avionics and automobiles. When using multicore platforms to host highly-critical workloads in these domains, the current state of the art is to obviate the predictability problem by turning off all but one core. Unless a more intelligent solution can be found, such domains will not benefit from savings in size, weight, and power (SWaP) and gains in functionality that multicore platforms afford.
M. Chisholm, N. Kim, B. Ward, N. Otterness, J. Anderson, and F.D. Smith, " Reconciling the Tension Between Hardware Isolation and Data Sharing in Mixed-Criticality, Multicore Systems", Proceedings of the 37th IEEE Real-Time Systems Symposium, December 2016, to appear. PDF . Longer version with all schedulability plots: PDF . Code is available here .
N. Kim, B. Ward, M. Chisholm, C.-Y. Fu, J. Anderson, and F.D. Smith, " Attacking the One-Out-Of-m Multicore Problem by Combining Hardware Management with Mixed-Criticality Provisioning", Proceedings of the 22nd IEEE Real-Time Embedded Technology and Applications Symposium, April 2016, to appear. Winner, outstanding paper award. PDF . Version with all schedulability graphs: PDF .
M. Chisholm, B. Ward, N. Kim, and J. Anderson, " Cache Sharing and Isolation Tradeoffs in Multicore Mixed-Criticality Systems", Proceedings of the 36th IEEE Real-Time Systems Symposium, pp. 305-316, December 2015. PDF . Longer version with more graphs: PDF .
B. Ward. " Relaxing Resource-Sharing Constraints for Improved Hardware Management and Schedulability", Proceedings of the 36th IEEE Real-Time Systems Symposium, December 2015. PDF .
B. Ward, J. Herman, C. Kenna, and J. Anderson, " Making Shared Caches More Predictable on Multicore Platforms", Proceedings of the 25th Euromicro Conference on Real-Time Systems, pp. 157-167, July 2013. Winner, outstanding paper award. PDF .
K. Yang and J. Anderson, " An Optimal Semi-Partitioned Scheduler for Uniform Heterogeneous Multiprocessors", Proceedings of the 27th Euromicro Conference on Real-Time Systems, pp. 199-210, July 2015. PDF .
K. Yang and J. Anderson, " Soft Real-Time Semi-Partitioned Scheduling with Restricted Migrations on Uniform Heterogeneous Multiprocessors", Proceedings of the 22nd International Conference on Real-Time Networks and Systems, pp. 215-224, October 2014. PDF .
J. Anderson, J. Erickson, U. Devi, and B. Casses, " Optimal Semi-Partitioned Scheduling in Soft Real-Time Systems", Proceedings of the 20th IEEE International Conference on Embedded and Real-Time Computing Systems and Applications, August 2014. Winner, best paper award. PDF . Longer version with more graphs: PDF . Code used in experiments: Compressed tar file .
R. Liu, A. Mills, and J. Anderson, " Independence Thresholds: Balancing Tractability and Practicality in Soft Real-Time Stochastic Analysis", Proceedings of the 35th IEEE Real-Time Systems Symposium, pp. 314-323, December 2014. PDF .
B. Ward, A. Thekkilakattil, and J. Anderson, " Optimizing Preemption-Overhead Accounting in Multiprocessor Real-Time Systems", Proceedings of the 22nd International Conference on Real-Time Networks and Systems, pp. 235-243, October 2014. PDF . Longer version with additional graphs: PDF .
G. Elliott, N. Kim, J. Erickson, C. Liu, and J. Anderson, " Response-Time Minimization of Automotive-Inspired Dataflows on Multicore Platforms", Proceedings of the 20th IEEE International Conference on Embedded and Real-Time Computing Systems and Applications, August 2014. PDF . Longer version with appendices: PDF .
K. Yang, M. Yang, and J. Anderson, " Reducing Response-Time Bounds for DAG-Based Task Systems on Heterogeneous Multicore Platforms", in submission. PDF . Longer version with additional graphs: PDF .
K. Yang and J. Anderson, " On the Dominance of Minimum-Parallelism Multiprocessor Supply", Proceedings of the 37th IEEE Real-Time Systems Symposium, December 2016, to appear. PDF . Longer version that includes all proofs: PDF .
N. Otterness, V. Miller, M. Yang, J. Anderson, and F.D. Smith, " GPU Sharing for Image Processing in Embedded Real-Time Systems", Proceedings of 12th Annual Workshop on Operating Systems Platforms for Embedded Real-Time Applications, pp. 23-29, July 2016. PDF . Longer version with more data: PDF .
C. Nemitz, K. Yang, M. Yang, P. Ekberg, and J. Anderson, " Multiprocessor Real-Time Locking Protocols for Replicated Resources", Proceedings of the 28th Euromicro Conference on Real-Time Systems, pp. 50-60, July 2016. PDF . Version with online appendices: PDF .
G. Elliott, K. Yang, and J. Anderson, " Supporting Real-Time Computer Vision Workloads using OpenVX on Multicore+GPU Platforms", Proceedings of the 36th IEEE Real-Time Systems Symposium, pp. 273-284, December 2015. PDF . Glenn Elliott's dissertation contains significantly more implementation details and experimental results than the paper.
C. Jarrett, B. Ward, and J. Anderson, " A Contention-Sensitive Fine-Grained Locking Protocol for Multiprocessor Real-Time Systems", Proceedings of the 23rd International Conference on Real-Time Networks and Systems, pp. 3-12, November 2015. PDF . Additional graphs: PDF .
K. Yang, G. Elliott, and J. Anderson, " Analysis for Supporting Real-Time Computer Vision Workloads using OpenVX on Multicore+GPU Platforms", Proceedings of the 23rd International Conference on Real-Time Networks and Systems, pp. 77-86, November 2015. PDF .
K. Yang and J. Anderson, " On the Soft Real-Time Optimality of Global EDF on Multiprocessors: From Identical to Uniform Heterogeneous", Proceedings of the 21st IEEE International Conference on Embedded and Real-Time Computing Systems and Applications, pp. 1-10, August 2015. PDF .
J. Erickson, N. Kim, and J. Anderson, " Recovering from Overload in Multicore Mixed-Criticality Systems", Proceedings of the 29th IEEE International Parallel and Distributed Processing Symposium, pp. 775-785, May 2015. PDF .
G. Elliott and J. Anderson, " Exploring the Multitude of Real-Time Multi-GPU Configurations", Proceedings of the 35th IEEE Real-Time Systems Symposium, pp. 260-271, December 2014. PDF . Longer version with appendices: PDF . Database of schedulability results .
K. Yang and J. Anderson, " Optimal GEDF-Based Schedulers that Allow Intra-Task Parallelism on Heterogeneous Multiprocessors", Proceedings of the The 12th IEEE Symposium on Embedded Systems for Real-Time Multimedia, pp. 30-39, October 2014. PDF .
N. Kim and J. Erickson and J. Anderson, " Mixed-Criticality on Multicore (MC2): A Status Report", Proceedings of the 10th International Workshop on Operating Systems Platforms for Embedded Real-Time Applications, pp. 45-50, July 2014. PDF .
B. Ward and J. Anderson, " Multi-Resource Real-Time Reader/Writer Locks for Multiprocessors", Proceedings of the 28th IEEE International Parallel and Distributed Processing Symposium, 177-186, May 2014. PDF .
G. Elliott, B. Ward, and J. Anderson, " GPUSync: A Framework for Real-Time GPU Management", Proceedings of the 34th IEEE Real-Time Systems Symposium, pp. 33-44, December 2013. PDF . Longer version with some additional details: PDF .
B. Ward and J. Anderson, " Fine-Grained Multiprocessor Real-Time Locking with Improved Blocking", Proceedings of the 21st International Conference on Real-Time Networks and Systems, pp. 67-76, October 2013. PDF .
J. Erickson and J. Anderson, " Reducing Tardiness Under Global Scheduling by Splitting Jobs", Proceedings of the 25th Euromicro Conference on Real-Time Systems, pp. 14-24, July 2013. PDF . Appendix: PDF .