Real-time Operating System Kernel Research Articles

Compositional virtual timelines: verifying dynamic-priority partitions with algorithmic temporal isolation

Real-time systems power safety-critical applications that require strong isolation among each other. Such isolation needs to be enforced at two orthogonal levels. On the micro-architectural level, this mainly involves avoiding interference through micro-architectural states, such as cache lines. On the algorithmic level, this is usually achieved by adopting real-time partitions to reserve resources for each application. Implementations of such systems are often complex and require formal verification to guarantee proper isolation. In this paper, we focus on algorithmic isolation, which is mainly related to scheduling-induced interferences. We address earliest-deadline-first (EDF) partitions to achieve compositionality and utilization, while imposing constraints on tasks' periods and enforcing budgets on these periodic partitions to ensure isolation between each other. The formal verification of such a real-time OS kernel is challenging due to the inherent complexity of the dynamic priority assignment on the partition level. We tackle this problem by adopting a dynamically constructed abstraction to lift the reasoning of a concrete scheduler into an abstract domain. Using this framework, we verify a real-time operating system kernel with budget-enforcing EDF partitions and prove that it indeed ensures isolation between partitions. All the proofs are mechanized in Coq.

Design of Embedded Ai Engine Based on the Microkernel Operating System

At present, the application of the embedded microkernel operating system in military and civil fields has begun to take shape, but it has not yet formed a unified method and standard. Due to its high performance, low frequency, and high reliability, dual-core embedded processors are getting the attention of many chip manufacturers. Compatibility has been favored by many telecom equipment manufacturers and embedded high-end application integrators, but the dual-core embedded processor needs a new real-time operating system to support it, so that it can give full play to the high performance of the dual-core. It paves the way for the application of its processor in the embedded field, but the design of embedded AI engine is not transparent to it; so, it needs the support of operating system. The user code is used to be in the operating system processor environment; so, it can be used on dual core processor first. In the real-time operating system that supports dual-core processors, the part that needs to be modified is mainly concentrated in the kernel part; so, the core design is the key point to support dual-core processors. This article is to seize this key point to carry out in-depth research. The difference and influence of hardware architecture between dual-core processor and single-core processor are the primary content of the study. Through the research of the dual-core processor architecture, the general abstraction of the dual-core processor architecture is obtained, which is the starting point of the follow-up research. This paper mainly studies the design of embedded AI engine based on the microkernel operating system, extracts the security requirements of the operating system, designs and implements the operating system from the perspective of formal verification, and considers the verification problem under the background of RTOS development, so as to avoid using too many complex data structures and algorithms in the system design and reduce the difficulty of experimental verification. In this paper, we use the spatiotemporal data model, data sharing security in the cloud environment, symmetric encryption scheme, and Paillier homomorphic encryption method to study the design of embedded AI engine based on the microkernel operating system. According to the idea of microkernel architecture, the kernel is divided into four main modules: task processing, semaphore, message queue, interrupt, and exception processing, and the lock mechanism to prevent reentrancy in software is analyzed separately. Three core function modules, initialization, process grinding, and interrupt processing, are extracted from the microkernel operating system to form the formal verification area of the operating system. At the same time, the system syntax and semantics of related rights are separated, and the main rationalization rules are described. The results show that the core of the microkernel operating system in five states adopts the microkernel architecture in the dual core environment. The microkernel architecture is a compact system kernel with good adjustability. Based on the analysis of the microkernel operating system, the internal structure of each module in the kernel is summarized, and the modules are modified according to the machine characteristics of the dual core processor; it corresponds to adding modules to meet the characteristics of dual core architecture. Kernel design is a systematic theoretical research process. This paper only uncovers the tip of the iceberg of real-time operating system kernel design on dual-core embedded processors. It is necessary to understand the kernel more deeply and master the kernel in the future work and study.

Research on A.C. Sampling Technique for the Electric Parameters Based on Embedded Linux and Frequency Self-Adapting

Directed at the traditional single chip microcomputer system which didn’t have the managing ability of the modern operating system, a technology of AC synchronization sampling was presented and implements which were based on embedded microprocessor S3C2410 and Linux real-time operating system kernel. The technology divided the sampling process into 2-part, frequency dynamic tracking and same-internal synchronization sampling .The multi-tasks, which process the different priorities, used to actualize sampling the signal and treating with the data. All tasks were scheduled by the preemptive Linux kernel. The technology has decreased the conflict between the precision and real-time property. The construction of hardware and software, method of constituting real-time operating system based on Linux kernel, signal frequency measuring, signal sampling and harmonic computing were introduced in detail.

PI-RTOS: Platform Independent RTOS

This paper proposes a Real-Time Operating System kernel for the 32-bit Leon3 processor. A system is said to be Real Time if it is required to complete its work and deliver its services on time. In a real-time system the correctness of its output, is an important factor, depends not only the logical computations carried out but also the time at which the results were delivered to the external interface. A Real time operating system (RTOS) is a class of operating system intended for real time applications. The requirements for developing an RTOS include RMS scheduling algorithm, file management scheme, interrupt handling, Timer etc. Most of these functions are in POSIX 1003.1b compliant. tsim simulator is used for compilation and debugging.. General Terms Interrupt handling, File management, Timer.

Research on Real-time Performance Testing Methods for Robot Operating System

To test real-time performance of RGMP-ROS, a robot operating system, this paper takes an in-depth study of the basic functions of real-time operating system kernel. By analyzing the main factors that affect the real-time performance of an operating system, we propose a set of real-time performance testing methods based on mixed load. This paper introduces the concept of the calibration procedure program. Takes the average execution time of the program as the standard time unit to normalize the test results of each test indicator, so as to shield the effect of the hardware test environment on the test results to a certain extent. While testing task preemption time and interrupt response time, we use background tasks that can trigger banning preemption or disabling interrupts to simulate the load, which makes the test results more real and reliable.

Research and Design of Embedded uC/OS-II Network Storage System

This article describes a network storage system, which is developed on the embedded system platform. It uses the open-source embedded real-time operating system kernel uCOS-II. Because the kernel is far from complete, such as the lack of a file system, device management, network protocol stack, graphical user interface, but it is small and open source.We extended its functions, such as to add LwIP network protocol stack, IDE hard drive, DM9000 NIC driver, NOR FALSH drive and a file system that supports large-capacity memory and etc, making it an embedded network storage system based on uCOS-II. DOI: http://dx.doi.org/10.11591/telkomnika.v11i4.2373

单侧Jacobi矩阵求逆算法及其DSP实现

链路自适应与先进接收机是宽带无线通信系统的核心技术，其设计与实现均涉及大量的矩阵分解以及矩阵求逆运算，提高矩阵分解和矩阵求逆运算的效率是提高宽带无线通信系统传输效能的基本途径。针对此目的，本文提出一种在经典Jacobi算法上改进的单侧Jacobi算法。由于该算法具有并行的特性，相比于串行（单核）实现在指令执行周期数上可提高至少两倍的运行效率。本文首先重点介绍改进的单侧Jacobi算法和TMS320C6474 DSP的内部架构与特性，然后重点阐述结合TI的实时多任务操作系统内核(DSP/BIOS)并行实现此算法，最后在同样精度的计算结果下比较并行算法与串行算法指令执行周期数，由此验证改进的单侧Jacobi算法在并行实现上的高效性。 Link adaptive transmission and advanced receiver are two key technologies in broadband wireless communi- cation system. The design and realization of the system both involve a large number of matrix decomposition and inver- sion. The basic way to improve transmission efficiency of broadband wireless communication system is to enhance the efficiency of matrix decompose and inverse computations. For this purpose, this paper develops a kind of one-sided Jacobi algorithm based on classic Jacobi. Since this algorithm has the characteristic of parallelism, it can increase the efficiency at least twice in terms of the instruction execution cycle numbers. This article will first focus on the im- proved one-sided Jacobi algorithm as well as internal architecture and characteristics of DSP TMS320C6474. It then elaborates on how to implement this algorithm in parallel using TI’s real-time multi-tasking operating system kernel (DSP/BIOS). Finally, this paper will compare instruction execution cycle numbers between parallel and serial algorithm under the same accuracy, proving the high efficiency of the improved one-sided Jacobi algorithm.

Опыт использования UniTESK как зеркало развития технологий тестирования на основе моделей

UniTESK (UNIfied TEsting and Specification toolKit) is a testing technology based on formal models (or specifications) of requirements to behavior of software or hardware components. It was created with experience gained during development of the framework for automated testing of a real-time operating system kernel during 1994-2000. Software contracts were the main kind of models in the first version of the technology. Automata models were also implemented to support generation of complicated test sequences. UniTESK was first used in 2000 in the development of the test suite for IPv6 implementation. It was the first experience of using contract specifications in testing of implementations of telecommunication protocols. This project demonstrated that contract specifications in combination with the technique of testing software systems with asynchronous interface developed within UniTESK are very effective. Applications of UniTESK to testing software components in Java include the project on testing of implementation of standard library for Java runtime support and the project on testing of infrastructure of information system for one of large mobile operators in Russia. The most significant application of UniTESK happened in 2005-2007 in the Open Linux Verification project. Formal specifications and tests for interfaces of the Linux Standard Base were created during the project. These results then were used in development of the test suite for Russian avionics real-time operating system. Positive lessons learned during development and using UniTESK include effective application of model based testing methods in large industrial projects, high level of test coverage achieved by the generated tests, applicability of model based testing to critical systems and applications. Negative lessons include the lack of well-defined and detailed models and specifications, extra development expenses caused by creation of test specific models, problems with introduction of model based testing technologies using bilingual test generation systems and specific notations.

RTOS kernel in portable electrocardiograph

This paper presents the use of a Real Time Operating System (RTOS) on a portable electrocardiograph based on a microcontroller platform. All medical device digital functions are performed by the microcontroller. The electrocardiograph CPU is based on the 18F4550 microcontroller, in which an uCOS-II RTOS can be embedded. The decision associated with the kernel use is based on its benefits, the license for educational use and its intrinsic time control and peripherals management. The feasibility of its use on the electrocardiograph is evaluated based on the minimum memory requirements due to the kernel structure. The kernel's own tools were used for time estimation and evaluation of resources used by each process. After this feasibility analysis, the migration from cyclic code to a structure based on separate processes or tasks able to synchronize events is used; resulting in an electrocardiograph running on one Central Processing Unit (CPU) based on RTOS.

Performance enhancement of real‐time computing for small unmanned helicopter autopilot

PurposeThe purpose of this paper is to make performance improvements and timely critical execution enhancements for operational flight program (OFP). The OFP is core software of autonomous control system of small unmanned helicopter.Design/methodology/approachIn order to meet the time constraints and enhance control application performance, two major improvements were done at real‐time operating system (RTOS) kernel. They are thread scheduling algorithm and lock‐free thread message communication mechanism. Both of them have a direct relationship with system efficiency and indirect relationship with helicopter control application execution stability through improved deadline keeping characteristics.FindingsIn this paper, the suitability of earliest deadline first (EDF) scheduling algorithm and non‐blocking buffer (NBB) mechanism are illustrated with experimental and practical applications. Results of this work show that EDF contributes around 15 per cent finer‐timely execution and NBB enhances kernel's responsiveness around 35 per cent with respect to the number of thread context switch and CPU utilization. These apply for OFP implemented over embedded configurable operating system (eCos) RTOS on x86 architecture‐based board.Practical implicationsThis paper illustrates an applicability of deadline‐based real‐time scheduling algorithm and lock‐free kernel communication mechanism for performance enhancement and timely critical execution of autonomous unmanned aerial vehicle control system.Originality/valueThis paper illustrates a novel approach to extend RTOS kernel modules based on unmanned aerial vehicle control application execution scenario. Lock‐free thread communication mechanism is implemented, and tested for applicability at RTOS. Relationship between UAV physical and computation modules are clearly illustrated via an appropriate unified modelling language (UML) collaboration and state diagrams. As experimental tests are conducted not only for a particular application, but also for various producer/consumer scenarios, these adequately demonstrate the applicability of extended kernel modules for general use.

A method to improve interrupt latency in real-time OS kernels

Interrupt latency has great impact on the real time and predictability of real-time operating system kernels. In traditional implementation of real-time kernels, interrupts are frequently disabled in system service routines, critical sections, etc., which causes kernel interrupt latency. In this paper we propose a method called PIL (Predictive Interrupt Latency). PIL reduces interrupt latency by never disabling interrupts during any system service routines. Moreover, it makes interrupt latency vary little, which improves the predictability in the response time for external events. We have implemented the PIL method in an OSEK-compatible operating system - SmartOSEK OS. Experimental results show PIL improves real time and predictability of real-time systems with low time and space overheads.

Design of a Digital System Dedicated for Electrical Drive Applications

The aim of this paper is to present the design of a rapid prototype drive system with small size, low cost and high effi-ciency. It depends basically on the personal computer (PC) processor without the need for any external processor (e.g. digital signal processor (DSP)) to get fast execution of control algorithms, and to support floating point operations. The PC-based rapid-prototyping system is dedicated for laboratory purposes and consists of an extension kit with all required interface boards to perform the simulation and implementation of electrical drive algorithms. Almost all designed boards are based on programmable-logic devices (PLD) to reduce cost and size.To operate the hardware of the proposed system, a free available open source real-time operating system (RTOS) kernel under Linux is used. A case study from electric drive area is selected and numerous experimental results are given in order to demonstrate the good functionality of the conceived system.

A SystemC refinement methodology for embedded software

This article presents a design environment that provides an interface for user-written SystemC modules that model application software to make calls to a real-time operating system (RTOS) kernel and cosimulate with user-written SystemC hardware modules. The environment also facilitates successive refinement through three abstraction layers for hardware-software codesign suitable for embedded-system design.

Development of an Ethernet-based equipment integration framework for factory automation

Traditional architectures of factory automation networks possess some shortcomings, such as needing gateways to transform communication data, using multiple different kinds of networks, needing higher maintenance cost, etc. To remedy the shortcomings, a novel Ethernet-based equipment integration framework is proposed in this paper. The proposed framework is qualified to be an equipment (synchronous) control network for the factory automation networking. Also, it conforms to the technical trend of replacing traditional industrial networks with Ethernet. Many technologies, including the master/slave model, Ethernet Switch, real-time operating system kernel, real-time transmission control protocol/Internet protocol application programming interface, and object request broker (ORB), are exploited to develop the framework. Simulation and experimental results for a laboratory-scale factory indicate that the proposed framework can perform well in real-time data transmission, that is, accomplishing the synchronous communication over 10 slave nodes within 1.4 ms. Additionally, the equipment integration framework can be easily integrated with the automation systems in the information-management layer through ORB. Worst-case performance evaluations and timing-parameter setting formulas for the proposed framework are also provided. The work presented here is believed to be a good paradigm for developing Ethernet-based factory automation networks.

A scalable single-chip multi-processor architecture with on-chip RTOS kernel

Now that system-on-chip technology is emerging, single-chip multi-processors are becoming feasible. A key problem of designing such systems is the complexity of their on-chip interconnects and memory architecture. It is furthermore unclear at what level software should be integrated. An example of a single-chip multi-processor for real-time (networked) embedded systems is the multi-microprocessor (MµP). Its architecture consists of a scalable number of identical master processors and a configurable set of shared co-processors. Additionally, an on-chip real-time operating system kernel is included to support transparent multi-tasking over the set of master processors. In this paper, we explore the main design issues of the architecture platform on which the MµP is based. In addition, synthesis results are presented for a lightweight configuration of this architecture platform.

REAL-TIME OBJECT-ORIENTED DISTRIBUTED SOFTWARE ENGINEERING AND THE TMO SCHEME

Real-time (RT) object-oriented (OO) distributed computing is a form of RT distributed computing realized with a distributed computer system structured in the form of an object network. Several approaches proposed in recent years for extending the conventional object structuring scheme to suit RT applications, are briefly reviewed. Then the approach to RT OO distributed computing which the author and his collaborators have been establishing in recent years will be reviewed in more detail. The approach named the TMO (Time-triggered Message-triggered Object) structuring scheme was formulated with the goal of instigating a quantum productivity jump in the design of complex real-time computing systems (RTCS's). The TMO scheme is intended to facilitate the pursuit of a new paradigm in designing RTCS's which is to realize real-time computing with a common and general design style that does not alienate the main-stream computing industry and yet to allow system engineers to confidently produce certifiable RTCS's for safety-critical applications. The TMO structuring scheme is a syntactically simple but semantically powerful extension of the conventional object structuring approaches and as such, its support tools can be based on various well-established OO programming languages such as C++ and JAVA and on ubiquitous commercial RT operating system kernels. The scheme enables a great reduction of the designer's efforts in guaranteeing timely service capabilities of application systems. Also, the scheme is applicable to structuring of not only complex distributed RTCS's but also application environment descriptors/simulators and requirement specifications.

Static priority scheduling of aperiodic real-time tasks

We investigate deadline meeting properties of the well-known (preemptive) static priority scheduling (SPS) algorithm, which is widespreadly used in commercial real-time operating system kernels. A discrete-time single server queueing system employing SPS for scheduling probabilistically arriving tasks at L priority levels is considered for this purpose. Model parameters are arrival and execution-time distribution A𝓁(z), L𝓁(z) and a (constant) deadline T𝓁∈ 𝒯L per level l. By means of a combinatorial technique (which does not require stable-state assumptions), we determine the probability distribution of the (random-)time the system operates without violating any task's deadline. This distribution is asymptotically exponential with parameter λ 𝒯 L , which decreases exponentially with the deadlines 𝒯L; simple asymptotic expressions for λ 𝒯 L and all associated quantities (probabilities, moments,…) for large 𝒯L are provided. Our numerical examples suggest that real-time systems based on SPS operate reasonably well only if computing performance is (more than) adequate. © 1997 John Wiley & Sons, Inc. Random Struct. Alg., 10, 257–303 (1997)

A tiny microcontroller dataflow kernel

A tiny real-time dataflow operating system kernel has been developed, named TERSE (Tiny Embedded Real-time Software Environment), initially for the 8051 series of microcontrollers, and version “G” is released into the public domain. Most embedded applications development, using small conventional-architecture single-chip microcontrollers, is done without an underlying software kernel, however the advantages of an operating system can be realised even at this low level. TERSE does not use the usual time-slicing/preemption of small RTOSs (Real-Time Operating Systems), but instead employs a cooperative dataflow model. The advantages seen, are modularity, easy parallelism, transparent distributed processing, a high level of determinism, object orientation, and timing enhancements for 1/O and real-time applications. Signature Scheduling, a combination of static and runtime scheduling, provides deterministic behaviour with the flexibility required of a reactive real-time system. It is also anticipated that there will be advantages in terms of reduced development time, in particular the meshing with high-level DFD/STD (Data Flow Diagram/State Transition Diagram) design tools, and easier maintenance, and a complementary flow-diagramming technique called tFlow has been developed. Also, TERSE is extremely easy to use, fast, and compact. The memory requirement of version G for the 8051, is about 420 bytes of ROM, including network interfacing, and the uniprocessor version is only 150 bytes.

Real time UNIX in embedded control-a case study within the context of LynxOS

Intelligent communication controllers for a layered protocol profile are a typical example of an embedded control application, where the classical approach for the software development is based on a proprietary real-time operating system kernel under which the individual layers are implemented as tasks. Based on the exemplary implementation of a derivative of MAP 3.0, an unusual and innovative approach is presented, where the protocol software is implemented under the UNIX-compatible real-time operating system LynxOS. The overall design of the embedded control application is presented under a more general view and economical implications as well as aspects of the development environment and performance are discussed.

Some Scheduling Experiments With Artie

In this paper we describe a new Architecture for hard Real-Time Environments (ARTIE). The architecture is essentially an asymmetrical two-processor system. It consists of a task processor for the application programs and the operating system's shell functions, and of a reliable co-processor for the real-time operating system kernel. We have formally derived the specifications for the kernel programs and proved that the programs behave according to the specifications. The practical performance of the system is evaluated by simulating a typical real-time application on a workstation.