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Multicore mixed-criticality with a hierarchical real-time scheduler and resource servers
Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology.
2015 (English)Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
Abstract [en]

This is a real-time mixed-criticality system on a dual-core Linux desktop. The hardware/software architecture employs memory throttling so that modules can be isolated in execution as well as in analysis/certification. There are two asymmetrically dedicated cores. A critical core runs a hierarchical scheduler (hs) with critical software: hard-coded, or Linux processes with associated metadata. The best-effort core runs arbitrary software. The cores share DRAM and the memory bus. Best- effort activity can delay critical software. Interference is throttled/bounded to retain real- time computability. When necessary, hs freezes/thaws best-effort core software. Task schedulers have budgets to bound memory interference. If depleted, the best-effort core is frozen whenever tasks from such a scheduler execute. Budgets are reset periodically. The scheduling algorithm is a polled-preemptive EDF, with critical-group CPU budgets. Task model: sporadic. Two resource servers uphold isolation in the face of shared resources: memory, and critical-core CPU time. A memory experiment shows that best-effort core activity is throttled dynamically. Alas, the submission mechanism lacks precision in worst- case scenarios: hs is itself suspectible to best-effort interference, so the throttling mechanism can brake before it can effectuate.

Place, publisher, year, edition, pages
2015. , 153 p.
IT, 15028
National Category
Engineering and Technology
URN: urn:nbn:se:uu:diva-253322OAI: oai:DiVA.org:uu-253322DiVA: diva2:814174
Educational program
Master Programme in Computer Science
Available from: 2015-05-26 Created: 2015-05-26 Last updated: 2015-05-26Bibliographically approved

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