دانلود رایگان ترجمه مقاله بررسی زمان واقعی سیستم عامل RTOS – نشریه IEEE 2014

بررسی زمان واقعی سیستم عامل: RTOS

The Survey Of Real Time Operating System: Rtos

Abstract

The paper discusses the literature survey of RTOS (Real Time Operating Systems) and its contributions to the embedded world. RTOS is defined as a system in which the correctness of the system does not depend only on the logical results of computation but also on the time at which the results are produced. It has to perform critical tasks on priority basis keeping the context switching time minimum. It is often associated with few misconceptions & we have tried to throw some light on it. Since last 20 years, RTOS is undergoing continuous evolution and has resulted into development of many commercial RTOS products. We have selected few commercial RTOS of different categories of real-time applications and have discussed its real-time features. A comparison of the commercial RTOSs’ is presented. We conclude by discussing the results of the survey and comparing the RTOS based on performance parameters.

I- Introduction

Last few years have seen the remarkable rise in the demand of embedded systems in human affairs. It has made its mark in every field ranging personal home affairs, business, and process automation in industries, communications, entertainment and defense. As we know, embedded system is a combination of hardware and software and perhaps other mechanical parts designed to perform a specific function [1]. We realize its contribution in making our life comfortable and safe, for that it has to satisfy time and memory constraints. The performance of these systems depends on the OS which are used. Most of these systems require RTOS for such a precise task. The first RTOS was produced more than 20 years ago by DEC for the PDP family of machines, which then undergone the process of evolution. Real time operating System (RTOS), as the name suggests provides a deadline associated with tasks and an RTOS adheres to this deadline as missing a deadline can cause affects ranging from undesired to catastrophic. RTOS must be deterministic and pre-emptive. An RTOS is effective and allows the real-time applications to be designed and expanded more easily whilst meeting the performances required. Abbreviations and Acronyms: IPC – Interprocess communication MPU – Microprocessor unit DEC – Digital Equipment Corporation LoC– Lines of code An operating system generally consists of two parts: kernel space (kernel mode) and user space (user mode).The basic part of any OS and which acts as a bridge between applications and the actual data processing at the hardware level, is a kernel. A kernel can provide the lowest-level abstraction layer for the resources (especially processors and I/O devices).

VII- CONCLUSIONS

Real time applications have become popular these days due to the complexity in the system. To meet those complexities, the developers are given the invariable task of making the real time software. There are quite large numbers of RTOS available in the market and one does get confused as to which one to select; such that it provides the efficient embedded systems design in terms of cost, power consumption, reliability, speed etc. Ranking RTOS is a tricky and difficult because there are so many good choices are available in the market. The developer can choose either commercial RTOS (44% developers are using) or opensource RTOS (20) or internally developed RTOS (17 %). From comparison and study of these selected commercial RTOS, we can infer that – RTAI and VxWorks provide a wide range of supported platforms. RTAI, an Open-source RTOS is most suited for small applications, such as robotics and medical devices. Whereas, VxWorks is dominant in highly complex and high performance applications. When we have many interrupts VxWorks is the better pick & it is faster than RTAI. Applications which are getting number of interrupts continuously in such case VxWorks should be preferred. Interrupts will tend to increase when number of inputs is applied to the RTOS simultaneously. In terms of message send/receive latency, RTAI is a better performer than VxWorks by a marginal difference. As mentioned earlier, these figures might vary to a large extent depending on the IPC implementation (IPC can be implemented using shared memory).