Scheduling and thread management with RTEMS

Bloom, Gedare; Sherrill, Joel

doi:10.1145/2597457.2597459

Cited by 14 publications

(5 citation statements)

References 4 publications

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“…The flight software is a self-contained C program, which is statically linked to the real-time operating system RTEMS [7]. To work around known bugs in the CPU a special, patched, GCC version is used to compile the software.…”

Section: Stix Instrument Onboard Solar Orbiter-backgroundmentioning

confidence: 99%

From Verified Scala to STIX File System Embedded Code Using Stainless

Hamza

Felix²,

Kunčak

et al. 2022

Lecture Notes in Computer Science

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We present an approach for using formal methods in embedded systems and its evaluation on a case study. In our approach, the developers describe the system in a restricted subset of the high-level programming language Scala. We then use 1) a verification system to formally prove properties of such Scala program, and 2) a source-tosource translator to map Scala to C code. We have adapted the Stainless verification system to support constructs for describing embedded software (more machine integer types and early returns) and to support verification patterns needed for embedded systems code (array swap operation, pre-allocated and initialized memory, constant-length arrays). The implemented C code translator generates code that can be compiled with compilers such as GCC and integrated into larger C applications. We evaluate our approach on a case study of a file system of an instrument on the Solar Orbiter satellite. We have ported around a thousand lines of C code to Scala. We wrote specification and proof hints to make the code verify. Stainless verified the absence of run-time errors, as well as function preconditions, postconditions, and data structure invariants. The generated C code was integrated into the existing code base and exhibits very similar code size, memory use, and performance. In this process we identified multiple bugs in the well-tested code base, which were fixed in-orbit.

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Section: Stix Instrument Onboard Solar Orbiter-backgroundmentioning

confidence: 99%

From Verified Scala to STIX File System Embedded Code Using Stainless

Hamza

Felix²,

Kunčak

et al. 2022

Lecture Notes in Computer Science

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“…We assume that each periodic task τ i , running in a sporadic server [64] with a processor capacity reserve [51], will have a maximum runtime of C i time-units in every T i time-units, as it is designed to be implemented in an RTOS like Quest [18]. We choose RMS because it is a low-overhead, fixed-priority scheduling algorithm that is popular in many RTOSs [4,10,18].…”

Section: Scheduling Modelmentioning

confidence: 99%

[Solution] End-to-end Scheduling of Real-time Task Pipelines on Multiprocessors

Sinha¹,

West²

2022

Journal of Systems Research

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Real-time embedded systems require significant analyses to ensure that their timing and functional correctness are met. With increasing complexities in hardware and software, this is a challenging proposition. Researchers have studied task-pipelines (also known as cause-effect chains) to deal with new applications in domains such as IoT and the advent of software frameworks such as ROS. In spite of increased usage of task pipelines there is scant work in analysis tools that can guarantee end-to-end properties. This paper aims to fix that by developing a constraint solver algorithm, "CoPi", that can derive runtime budgets and periods of individual pipelines tasks. This information can then be used to analyse the end-to-end constraints of the real-time system.The paper then extends this to multiprocessor systems that can handle multiple task pipelines, which in itself is quite a challenge. This fills a gap in the scheduling literature of pipeline-based task models and presents a nice heuristic optimization. The authors also present an extensive evaluation on open-source baselines for a large parameter space. Given the QoS constraints in many datacenter applications today, the paper also highlights possible design choices for scheduling in datacenter systems, thus demonstrating wide applicability. Hence CoPi has the potential to be influential in real-time, IoT and even datacenter systems.

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“…These requirements do not create a need to deploy it on top of a fully-fledged general-propose operating system, such as Linux or Windows, but we deem the implementation efforts large enough to warrant a tiny operating system. Thus, we ported the database engine to RTEMS (real-time executive for multiprocessor systems) [BS14], a mature, tailorable embedded real-time operating system (with a 25-year development history) that finds deployment in systems ranging from IoT devices to Mars orbiters. Similar to unikernel approaches [Br15;Ma13], RTEMS and the database engine are linked together into one single executable.…”

Section: Bare-metalmentioning

confidence: 99%

Silentium! Run-Analyse-Eradicate the Noise out of the DB/OS Stack

Mauerer,

Ramsauer,

Lucas

et al. 2021

Preprint

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When multiple tenants compete for resources, database performance tends to suffer. Yet there are scenarios where guaranteed sub-millisecond latencies are crucial, such as in real-time data processing, IoT devices, or when operating in safety-critical environments. In this paper, we study how to make query latencies deterministic in the face of noise (whether caused by other tenants or unrelated operating system tasks). We perform controlled experiments with an in-memory database engine in a multi-tenant setting, where we successively eradicate noisy interference from within the system software stack, to the point where the engine runs close to bare-metal on the underlying hardware.We show that we can achieve query latencies comparable to the database engine running as the sole tenant, but without noticeably impacting the workload of competing tenants. We discuss these results in the context of ongoing efforts to build custom operating systems for database workloads, and point out that for certain use cases, the margin for improvement is rather narrow. In fact, for scenarios like ours, existing operating systems might just be good enough, provided that they are expertly configured. We then critically discuss these findings in the light of a broader family of database systems (e.g. including disk-based), and how to extend the approach of this paper accordingly.

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Scheduling and thread management with RTEMS

Cited by 14 publications

References 4 publications

From Verified Scala to STIX File System Embedded Code Using Stainless

From Verified Scala to STIX File System Embedded Code Using Stainless

[Solution] End-to-end Scheduling of Real-time Task Pipelines on Multiprocessors

Silentium! Run-Analyse-Eradicate the Noise out of the DB/OS Stack

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