scholarly journals Using Hierarchical Scheduling to Support Soft Real-Time Applications in General-Purpose Operating Systems

2001 ◽  
Author(s):  
John D. Regehr
Keyword(s):  
Real Time ◽  
Operating Systems ◽  
General Purpose ◽  
Hierarchical Scheduling ◽  
Real Time Applications

scholarly journals Improving the Performance of CPU Architectures by Reducing the Operating System Overhead (Extended Version)

2016 ◽  
Vol 10 (1) ◽  
pp. 13-22
Author(s):  
Ionel Zagan ◽  
Vasile Gheorghita Gaitan
Keyword(s):  
Operating System ◽  
Real Time ◽  
Operating Systems ◽  
General Purpose ◽  
Program Counter ◽  
System Overhead ◽  
Multiple Threads ◽  
Real Time Applications ◽  
Hard Real Time ◽  
Time Systems

Abstract The predictable CPU architectures that run hard real-time tasks must be executed with isolation in order to provide a timing-analyzable execution for real-time systems. The major problems for real-time operating systems are determined by an excessive jitter, introduced mainly through task switching. This can alter deadline requirements, and, consequently, the predictability of hard real-time tasks. New requirements also arise for a real-time operating system used in mixed-criticality systems, when the executions of hard real-time applications require timing predictability. The present article discusses several solutions to improve the performance of CPU architectures and eventually overcome the Operating Systems overhead inconveniences. This paper focuses on the innovative CPU implementation named nMPRA-MT, designed for small real-time applications. This implementation uses the replication and remapping techniques for the program counter, general purpose registers and pipeline registers, enabling multiple threads to share a single pipeline assembly line. In order to increase predictability, the proposed architecture partially removes the hazard situation at the expense of larger execution latency per one instruction.

Real-Time Attributes in Operating Systems

2011 ◽  
pp. 275-287 ◽  
Author(s):  
Tommaso Cucinotta ◽  
Spyridon V. Gogouvitis
Keyword(s):  
Open Source ◽  
Real Time ◽  
Operating Systems ◽  
Distributed Applications ◽  
General Purpose ◽  
Multimedia Applications ◽  
Multimedia Contents ◽  
Wide Availability

General-Purpose Operating Systems (GPOSes) are being used more and more extensively to support interactive, real-time, and distributed applications, as found in the multimedia domain. In fact, the wide availability of supported multimedia devices and protocols, together with the wide availability of libraries and tools for handling multimedia contents, make them an almost ideal platform for the development of this kind of complex applications. However, contrarily to Real-Time Operating Systems, General-Purpose ones used to lack some important functionality needed for providing proper scheduling guarantees to application processes. Recently, the increasing use of GPOSes for multimedia applications is gradually pushing OS developers towards enriching the kernel of a GPOS so as to provide more and more real-time functionality, thus enhancing the performance and responsiveness of hosted time-sensitive applications. In this chapter, an overview is performed over the efforts done in the direction of enriching GPOSes with real-time capabilities, with a particular focus on the Linux OS. Due to its open-source nature and wide diffusion and availability, Linux is one of the most widely used OSes for such experimentations.

scholarly journals METHOD FOR ASSESSING OF RELIABILITY CHARACTERISTICS IN DESIGNING OF FAILURERESISTANT REAL-TIME OPERATING SYSTEMS

2020 ◽  
Vol 2 (61) ◽  
pp. 108-118
Author(s):  
P. Shvahirev ◽  
◽  
O. Lopakov ◽  
V. Kosmachevskiy ◽  
V. Salii ◽  
...  
Keyword(s):  
Response Time ◽  
Real Time ◽  
Operating Systems ◽  
Computer Systems ◽  
General Purpose ◽  
Input Output ◽  
Time System ◽  
Real Time System ◽  
Software Complex ◽  
External Events

For many years, real-time OS-based applications have been used in embedded special-purpose systems. Recently they have been used everywhere, from on-board control systems for aircraft, to household appliances. The development of multiprocessor computing systems usually aims to increase either the level of reliability or the level of system performance to values that are inaccessible or difficult to implement in traditional computer systems. In the first case, the question of the availability of special means of ensuring the fault tolerance of computer systems arises, the main feature (and advantage) of which is the absence of any single resource, failure of which leads to a fatal failure of the entire system. The use of a real-time operating system is always associated with equipment, with an object and with events occurring at an object. A real-time system, as a hardware-software complex, includes sensors that record events at an object, input / output modules that convert sensor readings into a digital form suitable for processing these readings on a computer, and finally, a computer with a program that responds to events occurring at the facility. The RTOS is focused on processing external events. It is this that leads to fundamental differences (compared with general-purpose OS) in the structure of the system as well as in the functions of the kernel and in the construction of the input-output system. The RTOS can be similar in its user interface to general-purpose operating systems, but it is completely different in its structure. In addition, the use of RTOS is always specific. If users (not developers) usually perceive a general-purpose OS as a ready-made set of applications, then the RTOS serves only as a tool for creating a specific hardware-software complex in real time. Therefore, the widest class of users of RTOS is the developers of real-time complexes, people designing control and data collection systems. When designing and developing a specific real-time system, the programmer always knows exactly what events can occur at the facility, and he knows the critical terms for servicing each of these events. We call a real-time system (SRV) a hardware-software complex that responds in predictable times to an unpredictable stream of external events. The system must have time to respond to the event that occurred at the facility, during the time critical for this event. The critical time for each event is determined by the object and by the event itself, and, of course, it can be different, but the response time of the system must be predicted (calculated) when creating the system. Lack of response at the predicted time is considered an error for real-time systems. The system must have time to respond to simultaneously occurring events. Even if two or more external events occur simultaneously, the system must have time to respond to each of them during time intervals critical for these events. In this study, as part of a network fault-tolerant technology, the RTOS becomes a special type of control software that is used to organize the operation of embedded applications, which are characterized by limited memory resources, low productivity and the requirements of a guaranteed response time (T<4 μs), high level availability and availability of auto-monitoring facilities.

scholarly journals Performance analysis of real-time and general-purpose operating systems for path planning of the multi-robot systems

2022 ◽  
Vol 12 (1) ◽  
pp. 285
Author(s):  
Seçkin Canbaz ◽  
Gökhan Erdemir
Keyword(s):  
Path Planning ◽  
Real Time ◽  
Operating Systems ◽  
General Purpose ◽  
High Priority Task ◽  
Tracking Tasks ◽  
Priority Task ◽  
Robot Systems ◽  
Robotic Applications ◽  
Multi Robot

In general, modern operating systems can be divided into two essential parts, real-time operating systems (RTOS) and general-purpose operating systems (GPOS). The main difference between GPOS and RTOS is the system istime-critical or not. It means that; in GPOS, a high-priority thread cannot preempt a kernel call. But, in RTOS, a low-priority task is preempted by a high-priority task if necessary, even if it’s executing a kernel call. Most Linux distributions can be used as both GPOS and RTOS with kernel modifications. In this study, two Linux distributions, Ubuntu and Pardus, were analyzed and their performances were compared both as GPOS and RTOS for path planning of the multi-robot systems. Robot groups with different numbers of members were used to perform the path tracking tasks using both Ubuntu and Pardus as GPOS and RTOS. In this way, both the performance of two different Linux distributions in robotic applications were observed and compared in two forms, GPOS, and RTOS.

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