Contents
1. Concepts of Real time Systems (RTS)
2. Characteristics of RTS
3. Types of RTS
4. Comparison between Types of RTS
5. Applications of RTS
6. Challenges of RTS
Static modeling represents the static elements of software such as classes, objects, and interfaces and their relationships. It includes class diagrams and object diagrams. Class diagrams show classes, attributes, and relationships between classes. Object diagrams show instances of classes and their properties. Dynamic modeling represents the behavior and interactions of static elements through interaction diagrams like sequence diagrams and communication diagrams, as well as activity diagrams.
The document discusses clock-driven scheduling for real-time systems. It covers key concepts like static schedules, cyclic executives, frame size constraints, job slicing, and algorithms for constructing static schedules. Notations are introduced to represent periodic tasks, and assumptions made for clock-driven scheduling are explained. Methods to improve the average response time of aperiodic jobs through slack stealing are also summarized.
This document discusses real-time scheduling algorithms. It begins by defining real-time systems and their key properties of timeliness and predictability. It then discusses two common real-time scheduling algorithms: fixed-priority Rate Monotonic scheduling and dynamic-priority Earliest Deadline First scheduling. It covers how each algorithm prioritizes and orders tasks, and analyzes their schedulability and utilization bounds. It concludes by comparing the two approaches.
This document provides an overview of concepts related to time and clock synchronization in distributed systems. It discusses the need to synchronize clocks across different computers to accurately timestamp events. Physical clocks drift over time so various clock synchronization algorithms like Cristian's algorithm and Berkeley algorithm are presented to synchronize clocks within a known bound. The Network Time Protocol (NTP) used on the internet to synchronize client clocks to UTC sources through a hierarchy of time servers is also summarized. Logical clocks provide an alternative to physical clock synchronization by assigning timestamps to events based on their order of occurrence.
Unit 1 architecture of distributed systemskaran2190
The document discusses the architecture of distributed systems. It describes several models for distributed system architecture including:
1) The mini computer model which connects multiple minicomputers to share resources among users.
2) The workstation model where each user has their own workstation and resources are shared over a network.
3) The workstation-server model combines workstations with centralized servers to manage shared resources like files.
1. Real-time systems are systems where the correctness depends on both the logical result and the time at which the results are produced.
2. Real-time systems have performance deadlines where computations and actions must be completed. Deadlines can be time-driven or event-driven.
3. Real-time systems are classified as hard, firm, or soft depending on how critical meeting deadlines are. They are used in applications like medical equipment, automotive systems, and avionics.
A Distributed File System(DFS) is simply a classical model of a file system distributed across multiple machines.The purpose is to promote sharing of dispersed files.
Static modeling represents the static elements of software such as classes, objects, and interfaces and their relationships. It includes class diagrams and object diagrams. Class diagrams show classes, attributes, and relationships between classes. Object diagrams show instances of classes and their properties. Dynamic modeling represents the behavior and interactions of static elements through interaction diagrams like sequence diagrams and communication diagrams, as well as activity diagrams.
The document discusses clock-driven scheduling for real-time systems. It covers key concepts like static schedules, cyclic executives, frame size constraints, job slicing, and algorithms for constructing static schedules. Notations are introduced to represent periodic tasks, and assumptions made for clock-driven scheduling are explained. Methods to improve the average response time of aperiodic jobs through slack stealing are also summarized.
This document discusses real-time scheduling algorithms. It begins by defining real-time systems and their key properties of timeliness and predictability. It then discusses two common real-time scheduling algorithms: fixed-priority Rate Monotonic scheduling and dynamic-priority Earliest Deadline First scheduling. It covers how each algorithm prioritizes and orders tasks, and analyzes their schedulability and utilization bounds. It concludes by comparing the two approaches.
This document provides an overview of concepts related to time and clock synchronization in distributed systems. It discusses the need to synchronize clocks across different computers to accurately timestamp events. Physical clocks drift over time so various clock synchronization algorithms like Cristian's algorithm and Berkeley algorithm are presented to synchronize clocks within a known bound. The Network Time Protocol (NTP) used on the internet to synchronize client clocks to UTC sources through a hierarchy of time servers is also summarized. Logical clocks provide an alternative to physical clock synchronization by assigning timestamps to events based on their order of occurrence.
Unit 1 architecture of distributed systemskaran2190
The document discusses the architecture of distributed systems. It describes several models for distributed system architecture including:
1) The mini computer model which connects multiple minicomputers to share resources among users.
2) The workstation model where each user has their own workstation and resources are shared over a network.
3) The workstation-server model combines workstations with centralized servers to manage shared resources like files.
1. Real-time systems are systems where the correctness depends on both the logical result and the time at which the results are produced.
2. Real-time systems have performance deadlines where computations and actions must be completed. Deadlines can be time-driven or event-driven.
3. Real-time systems are classified as hard, firm, or soft depending on how critical meeting deadlines are. They are used in applications like medical equipment, automotive systems, and avionics.
A Distributed File System(DFS) is simply a classical model of a file system distributed across multiple machines.The purpose is to promote sharing of dispersed files.
The document discusses network planning models for project scheduling. It describes two main techniques: CPM (Critical Path Method) and PERT (Program Evaluation Review Technique). Both use an "activity-on-arrow" approach where activities are drawn as arrows between nodes representing start and end times. More recently, precedence networks use an "activity-on-node" approach where activities are represented as nodes and dependencies as lines between nodes. The document provides examples of constructing precedence networks and performing forward and backward passes to determine the critical path and calculate total float for activities.
The document discusses requirements analysis and analysis modeling principles for software engineering. It covers key topics such as:
1. Requirements analysis specifies a software's operational characteristics and interface with other systems to establish constraints. Analysis modeling focuses on what the software needs to do, not how it will be implemented.
2. Analysis modeling principles include representing the information domain, defining functions, modeling behavior, partitioning complex problems, and moving from essential information to implementation details.
3. Common analysis techniques involve use case diagrams, class diagrams, state diagrams, data flow diagrams, and data modeling to define attributes, relationships, cardinality and modality between data objects.
Group Communication (Distributed computing)Sri Prasanna
This document discusses different modes of communication in distributed systems including unicast, anycast, multicast, and broadcast. It then covers topics related to implementing group communication such as hardware vs software approaches, reliability, ordering of messages, and protocols like IP multicast and IGMP.
This document provides an overview of a reference model for real-time systems. It describes the key components of the model including the workload model (tasks and jobs), resource model (processors and resources), and scheduling algorithms. It defines temporal parameters for jobs, periodic and sporadic task models, and different types of dependencies. It also covers functional parameters, resource requirements, and defines concepts like feasibility and optimality for schedules. The goal is to characterize real-time systems and provide a framework for analyzing scheduling and resource allocation algorithms.
This document discusses real-time operating systems (RTOS). It defines RTOS as operating systems that are able to respond to inputs immediately within a specified time delay. It compares RTOS to general operating systems and discusses the types, characteristics, functions, and applications of RTOS. Examples of RTOS like VxWorks are provided. The key functions of an RTOS include task management, scheduling, resource allocation, and interrupt handling. RTOS are widely used in applications that require deterministic responses like avionics, medical devices, industrial automation, and more.
Fault tolerance is important for distributed systems to continue functioning in the event of partial failures. There are several phases to achieving fault tolerance: fault detection, diagnosis, evidence generation, assessment, and recovery. Common techniques include replication, where multiple copies of data are stored at different sites to increase availability if one site fails, and check pointing, where a system's state is periodically saved to stable storage so the system can be restored to a previous consistent state if a failure occurs. Both techniques have limitations around managing consistency with replication and overhead from checkpointing communications and storage requirements.
Synchronization in distributed computingSVijaylakshmi
Synchronization in distributed systems is achieved via clocks. The physical clocks are used to adjust the time of nodes. Each node in the system can share its local time with other nodes in the system. The time is set based on UTC (Universal Time Coordination).
The COCOMO model is a widely used software cost estimation model that predicts development effort and schedule based on project attributes. It includes basic, intermediate, and detailed models of increasing complexity. The intermediate model estimates effort as a function of source lines of code and cost drivers. The detailed model further incorporates the impact of cost drivers on development phases. COCOMO 2 expands on this with application composition, early design, reuse, and post-architecture models for different project stages.
This document provides an overview of PAC (Probably Approximately Correct) learning theory. It discusses how PAC learning relates the probability of successful learning to the number of training examples, complexity of the hypothesis space, and accuracy of approximating the target function. Key concepts explained include training error vs true error, overfitting, the VC dimension as a measure of hypothesis space complexity, and how PAC learning bounds can be derived for finite and infinite hypothesis spaces based on factors like the training size and VC dimension.
This document outlines a 10-step process called Step Wise for project planning. It involves selecting the project, identifying objectives and scope, analyzing project characteristics, identifying products and activities, estimating effort, identifying risks, allocating resources, reviewing and publishing the plan, and executing the plan through lower levels of detailed planning. Project planning establishes objectives, analyzes the project, and identifies an infrastructure, products, activities, resources, and quality controls to guide successful execution.
This document discusses key aspects of distributed file systems including file caching schemes, file replication, and fault tolerance. It describes different cache locations, modification propagation techniques, and methods for replica creation. File caching schemes aim to reduce network traffic by retaining recently accessed files in memory. File replication provides increased reliability and availability through independent backups. Distributed file systems must also address being stateful or stateless to maintain information about file access and operations.
This document discusses software architecture from both a management and technical perspective. From a management perspective, it defines an architecture as the design concept, an architecture baseline as tangible artifacts that satisfy stakeholders, and an architecture description as a human-readable representation of the design. It also notes that mature processes, clear requirements, and a demonstrable architecture are important for predictable project planning. Technically, it describes Philippe Kruchten's model of software architecture, which includes use case, design, process, component, and deployment views that model different aspects of realizing a system's design.
This document discusses resource management techniques in distributed systems. It covers three main scheduling techniques: task assignment approach, load balancing approach, and load sharing approach. It also outlines desirable features of good global scheduling algorithms such as having no a priori knowledge about processes, being dynamic in nature, having quick decision-making capability, balancing system performance and scheduling overhead, stability, scalability, fault tolerance, and fairness of service. Finally, it discusses policies for load estimation, process transfer, state information exchange, location, priority assignment, and migration limiting that distributed load balancing algorithms employ.
what is COCOMO Model in software project management
COCOMO Model in software project management defined
COCOMO Model in software project management
what is cocomo model
cocomo model and its application
Aspect-Oriented Software Development (AOSD) is a programming methodology that addresses limitations in object-oriented programming for modularizing cross-cutting concerns. AOSD uses aspects to encapsulate cross-cutting concerns so they can be separated from the core functionality. Aspects are automatically incorporated into the system by a weaver. This improves modularity and makes software easier to maintain and evolve over time.
Distributed deadlock occurs when processes are blocked while waiting for resources held by other processes in a distributed system without a central coordinator. There are four conditions for deadlock: mutual exclusion, hold and wait, non-preemption, and circular wait. Deadlock can be addressed by ignoring it, detecting and resolving occurrences, preventing conditions through constraints, or avoiding it through careful resource allocation. Detection methods include centralized coordination of resource graphs or distributed probe messages to identify resource waiting cycles. Prevention strategies impose timestamp or age-based priority to resource requests to eliminate cycles.
This document discusses different file models and methods for accessing files. It describes unstructured and structured file models, as well as mutable and immutable files. It also covers remote file access using remote service and data caching models. Finally, it discusses different units of data transfer for file access, including file-level, block-level, byte-level, and record-level transfer models.
Architecture design in software engineeringPreeti Mishra
The document discusses software architectural design. It defines architecture as the structure of a system's components, their relationships, and properties. An architectural design model is transferable across different systems. The architecture enables analysis of design requirements and consideration of alternatives early in development. It represents the system in an intellectually graspable way. Common architectural styles structure systems and their components in different ways, such as data-centered, data flow, and call-and-return styles.
This document discusses various topics related to synchronization in distributed systems, including distributed algorithms, logical clocks, global state, and leader election. It provides definitions and examples of key synchronization concepts such as coordination, synchronization, and determining global states. Examples of logical clock algorithms like Lamport clocks and vector clocks are provided. Challenges around clock synchronization and calculating global system states are also summarized.
Real-time operating systems are designed to handle tasks with strict timing constraints. They manage computer hardware resources and provide services to real-time computer programs. Real-time tasks must be completed by their deadlines to maintain the correct functionality of systems like digital controls that periodically sense status and actuate systems. Real-time operating systems prioritize predictability and ensuring tasks meet timing deadlines over average performance metrics. They schedule processors and allocate memory in a way that guarantees tasks will finish processing by their required times.
Survey of Real Time Scheduling AlgorithmsIOSR Journals
This document summarizes and reviews real-time scheduling algorithms. It discusses both static and dynamic scheduling algorithms for real-time tasks on uniprocessors and multiprocessors. The document reviews algorithms such as Earliest Deadline First, Least Laxity First, and Modified Instantaneous Utilization Factor Scheduling. It concludes that Modified Instantaneous Utilization Factor Scheduling provides better results than previous algorithms in terms of context switching, response time, and CPU utilization for uniprocessor scheduling.
Real-time systems include applications like digital control, command and control, and signal processing. These systems monitor physical processes using sensors and control them using actuators. A real-time controller estimates the current state of the physical process from sensor readings and computes control outputs to activate actuators and keep the process in a desired state. Many real-time systems have hard deadlines that must be met to avoid dangerous consequences. Examples include flight controllers and medical systems. Soft real-time systems have deadlines that are undesirable but not fatal to miss.
The document discusses network planning models for project scheduling. It describes two main techniques: CPM (Critical Path Method) and PERT (Program Evaluation Review Technique). Both use an "activity-on-arrow" approach where activities are drawn as arrows between nodes representing start and end times. More recently, precedence networks use an "activity-on-node" approach where activities are represented as nodes and dependencies as lines between nodes. The document provides examples of constructing precedence networks and performing forward and backward passes to determine the critical path and calculate total float for activities.
The document discusses requirements analysis and analysis modeling principles for software engineering. It covers key topics such as:
1. Requirements analysis specifies a software's operational characteristics and interface with other systems to establish constraints. Analysis modeling focuses on what the software needs to do, not how it will be implemented.
2. Analysis modeling principles include representing the information domain, defining functions, modeling behavior, partitioning complex problems, and moving from essential information to implementation details.
3. Common analysis techniques involve use case diagrams, class diagrams, state diagrams, data flow diagrams, and data modeling to define attributes, relationships, cardinality and modality between data objects.
Group Communication (Distributed computing)Sri Prasanna
This document discusses different modes of communication in distributed systems including unicast, anycast, multicast, and broadcast. It then covers topics related to implementing group communication such as hardware vs software approaches, reliability, ordering of messages, and protocols like IP multicast and IGMP.
This document provides an overview of a reference model for real-time systems. It describes the key components of the model including the workload model (tasks and jobs), resource model (processors and resources), and scheduling algorithms. It defines temporal parameters for jobs, periodic and sporadic task models, and different types of dependencies. It also covers functional parameters, resource requirements, and defines concepts like feasibility and optimality for schedules. The goal is to characterize real-time systems and provide a framework for analyzing scheduling and resource allocation algorithms.
This document discusses real-time operating systems (RTOS). It defines RTOS as operating systems that are able to respond to inputs immediately within a specified time delay. It compares RTOS to general operating systems and discusses the types, characteristics, functions, and applications of RTOS. Examples of RTOS like VxWorks are provided. The key functions of an RTOS include task management, scheduling, resource allocation, and interrupt handling. RTOS are widely used in applications that require deterministic responses like avionics, medical devices, industrial automation, and more.
Fault tolerance is important for distributed systems to continue functioning in the event of partial failures. There are several phases to achieving fault tolerance: fault detection, diagnosis, evidence generation, assessment, and recovery. Common techniques include replication, where multiple copies of data are stored at different sites to increase availability if one site fails, and check pointing, where a system's state is periodically saved to stable storage so the system can be restored to a previous consistent state if a failure occurs. Both techniques have limitations around managing consistency with replication and overhead from checkpointing communications and storage requirements.
Synchronization in distributed computingSVijaylakshmi
Synchronization in distributed systems is achieved via clocks. The physical clocks are used to adjust the time of nodes. Each node in the system can share its local time with other nodes in the system. The time is set based on UTC (Universal Time Coordination).
The COCOMO model is a widely used software cost estimation model that predicts development effort and schedule based on project attributes. It includes basic, intermediate, and detailed models of increasing complexity. The intermediate model estimates effort as a function of source lines of code and cost drivers. The detailed model further incorporates the impact of cost drivers on development phases. COCOMO 2 expands on this with application composition, early design, reuse, and post-architecture models for different project stages.
This document provides an overview of PAC (Probably Approximately Correct) learning theory. It discusses how PAC learning relates the probability of successful learning to the number of training examples, complexity of the hypothesis space, and accuracy of approximating the target function. Key concepts explained include training error vs true error, overfitting, the VC dimension as a measure of hypothesis space complexity, and how PAC learning bounds can be derived for finite and infinite hypothesis spaces based on factors like the training size and VC dimension.
This document outlines a 10-step process called Step Wise for project planning. It involves selecting the project, identifying objectives and scope, analyzing project characteristics, identifying products and activities, estimating effort, identifying risks, allocating resources, reviewing and publishing the plan, and executing the plan through lower levels of detailed planning. Project planning establishes objectives, analyzes the project, and identifies an infrastructure, products, activities, resources, and quality controls to guide successful execution.
This document discusses key aspects of distributed file systems including file caching schemes, file replication, and fault tolerance. It describes different cache locations, modification propagation techniques, and methods for replica creation. File caching schemes aim to reduce network traffic by retaining recently accessed files in memory. File replication provides increased reliability and availability through independent backups. Distributed file systems must also address being stateful or stateless to maintain information about file access and operations.
This document discusses software architecture from both a management and technical perspective. From a management perspective, it defines an architecture as the design concept, an architecture baseline as tangible artifacts that satisfy stakeholders, and an architecture description as a human-readable representation of the design. It also notes that mature processes, clear requirements, and a demonstrable architecture are important for predictable project planning. Technically, it describes Philippe Kruchten's model of software architecture, which includes use case, design, process, component, and deployment views that model different aspects of realizing a system's design.
This document discusses resource management techniques in distributed systems. It covers three main scheduling techniques: task assignment approach, load balancing approach, and load sharing approach. It also outlines desirable features of good global scheduling algorithms such as having no a priori knowledge about processes, being dynamic in nature, having quick decision-making capability, balancing system performance and scheduling overhead, stability, scalability, fault tolerance, and fairness of service. Finally, it discusses policies for load estimation, process transfer, state information exchange, location, priority assignment, and migration limiting that distributed load balancing algorithms employ.
what is COCOMO Model in software project management
COCOMO Model in software project management defined
COCOMO Model in software project management
what is cocomo model
cocomo model and its application
Aspect-Oriented Software Development (AOSD) is a programming methodology that addresses limitations in object-oriented programming for modularizing cross-cutting concerns. AOSD uses aspects to encapsulate cross-cutting concerns so they can be separated from the core functionality. Aspects are automatically incorporated into the system by a weaver. This improves modularity and makes software easier to maintain and evolve over time.
Distributed deadlock occurs when processes are blocked while waiting for resources held by other processes in a distributed system without a central coordinator. There are four conditions for deadlock: mutual exclusion, hold and wait, non-preemption, and circular wait. Deadlock can be addressed by ignoring it, detecting and resolving occurrences, preventing conditions through constraints, or avoiding it through careful resource allocation. Detection methods include centralized coordination of resource graphs or distributed probe messages to identify resource waiting cycles. Prevention strategies impose timestamp or age-based priority to resource requests to eliminate cycles.
This document discusses different file models and methods for accessing files. It describes unstructured and structured file models, as well as mutable and immutable files. It also covers remote file access using remote service and data caching models. Finally, it discusses different units of data transfer for file access, including file-level, block-level, byte-level, and record-level transfer models.
Architecture design in software engineeringPreeti Mishra
The document discusses software architectural design. It defines architecture as the structure of a system's components, their relationships, and properties. An architectural design model is transferable across different systems. The architecture enables analysis of design requirements and consideration of alternatives early in development. It represents the system in an intellectually graspable way. Common architectural styles structure systems and their components in different ways, such as data-centered, data flow, and call-and-return styles.
This document discusses various topics related to synchronization in distributed systems, including distributed algorithms, logical clocks, global state, and leader election. It provides definitions and examples of key synchronization concepts such as coordination, synchronization, and determining global states. Examples of logical clock algorithms like Lamport clocks and vector clocks are provided. Challenges around clock synchronization and calculating global system states are also summarized.
Real-time operating systems are designed to handle tasks with strict timing constraints. They manage computer hardware resources and provide services to real-time computer programs. Real-time tasks must be completed by their deadlines to maintain the correct functionality of systems like digital controls that periodically sense status and actuate systems. Real-time operating systems prioritize predictability and ensuring tasks meet timing deadlines over average performance metrics. They schedule processors and allocate memory in a way that guarantees tasks will finish processing by their required times.
Survey of Real Time Scheduling AlgorithmsIOSR Journals
This document summarizes and reviews real-time scheduling algorithms. It discusses both static and dynamic scheduling algorithms for real-time tasks on uniprocessors and multiprocessors. The document reviews algorithms such as Earliest Deadline First, Least Laxity First, and Modified Instantaneous Utilization Factor Scheduling. It concludes that Modified Instantaneous Utilization Factor Scheduling provides better results than previous algorithms in terms of context switching, response time, and CPU utilization for uniprocessor scheduling.
Real-time systems include applications like digital control, command and control, and signal processing. These systems monitor physical processes using sensors and control them using actuators. A real-time controller estimates the current state of the physical process from sensor readings and computes control outputs to activate actuators and keep the process in a desired state. Many real-time systems have hard deadlines that must be met to avoid dangerous consequences. Examples include flight controllers and medical systems. Soft real-time systems have deadlines that are undesirable but not fatal to miss.
The document provides information about real-time systems and real-time operating systems (RTOS). It defines a real-time system as one where the correctness depends not only on logical results but also the time when results are delivered. An RTOS is designed to meet the strict timing constraints of real-time applications through features like multitasking, interrupt handling, and predictable scheduling. Key considerations for selecting an RTOS include its real-time capabilities, footprint, interrupt latencies, available APIs, and development tools.
An embedded system is a combination of hardware and software that is designed to perform a dedicated function. Embedded systems monitor, respond to, or control external environments through sensors, actuators and other I/O interfaces. They must meet real-time constraints imposed by the environment. Common applications include industrial automation, medical devices, vehicles, and consumer electronics.
PREDICTIVE DETECTION OF KNOWN SECURITY CRITICALITIES IN CYBER PHYSICAL SYSTEM...cscpconf
A large number of existing Cyber Physical Systems (CPS) in production environments, also employed in critical infrastructures, are severely vulnerable to cyber threats but cannot be modified due to strict availability requirements and nearly impossible change management. Monitoring solutions are increasingly proving to be very effective in such scenarios. Since CPS are typically designed for a precise purpose, their behaviour is predictable to a good extent and often well known, both from the process and the cyber perspective. This work presents a cyber security monitor capable of leveraging such knowledge to detect illicit activities. It uses a formal language to specify critical conditions and an SMT-based engine to detect them through network traffic and log analysis. The framework is predictive, i.e. it recognises if the system is approaching a critical state before reaching it. An important novelty of the approach is the capability of dealing with unobservable variables, making the framework much more feasible in real cases. This work presents the formal framework and first experimental results validating the feasibility of the approach.
Real time systems must produce correct responses within defined time limits. Failure to do so can result in system degradation or malfunction. Real time systems are categorized based on their deadline requirements as hard, firm, or soft. Hard systems must meet deadlines or fail, while soft systems can tolerate missed deadlines with degraded performance. Real time systems are used in critical applications like aircraft control systems, medical equipment, traffic control and more. They interact with the physical world through sensors and actuators and require real time operating systems to ensure timing constraints are met.
Real-time operating systems (RTOS) are used in embedded systems, industrial robots, and other applications that require timely and predictable responses. An RTOS guarantees tasks will complete within specified time constraints. There are two main types of RTOS designs - event-driven systems that change state in response to events, and time-sharing systems that switch tasks on a time schedule. Common RTOS scheduling algorithms include priority-based preemptive scheduling, round-robin scheduling, and fixed-priority scheduling. An RTOS must efficiently schedule tasks, provide interprocess communication, and prevent processes from accessing shared data simultaneously.
This document discusses real-time data and real-time systems. It defines real-time systems as systems where the correctness depends on both the logical result and the time the result is produced. Real-time systems must respond to events in a fast and predictable way. The document discusses soft, firm, and hard deadlines and gives examples of hard real-time systems like nuclear reactor control. It also discusses challenges in validating that a real-time system can meet all its timing constraints and potential solutions like real-time operating systems and distributed systems.
This document discusses real-time systems and scheduling techniques. It defines real-time systems as those where timing requirements are as important as functional requirements. Examples include airplane control systems, medical equipment, and industrial control. Key aspects of real-time systems include predictability, isolation of critical and non-critical activities, and guaranteeing timing requirements through scheduling algorithms. The document then describes different scheduling approaches like static, dynamic, and hybrid techniques and algorithms like fixed-priority scheduling and earliest deadline first.
Benchmark methods to analyze embedded processors and systemsXMOS
xCORE multicore microcontrollers are 100x more responsive than traditional micros. The unparalleled responsiveness of the xCORE I/O ports is rooted in some fundamental features:
- Single cycle instruction execution
- No interrupts
- No cache
- Multiple cores allow concurrent independent task execution
- Hardware scheduler performs 'RTOS-like' functions
This document discusses real-time systems and real-time scheduling algorithms. It defines hard and soft real-time tasks and lists examples of real-time systems. It describes five key characteristics of real-time operating systems: determinism, responsiveness, user control, reliability, and fail-soft operation. Two popular scheduling algorithms are discussed: deadline scheduling, which prioritizes the task with the earliest deadline, and rate monotonic scheduling, which prioritizes tasks based on their periods so that higher rate tasks have higher priority. An example of each algorithm is provided.
The document discusses real-time embedded systems and real-time operating system (RTOS) scheduling. It introduces key concepts like hard and soft real-time systems, embedded systems, and RTOS scheduling techniques including round robin, function pointer based, and priority-based preemptive scheduling. The document also covers rate monotonic scheduling and static priority driven preemptive scheduling assumptions and theorems.
The document discusses real-time embedded systems and real-time operating system (RTOS) scheduling. It introduces key concepts like hard and soft real-time systems, embedded systems, and RTOS scheduling techniques including round robin, function pointer based, and priority-based preemptive scheduling. The document also covers rate monotonic scheduling and static priority driven preemptive scheduling assumptions and theorems.
The document discusses real-time systems and scheduling strategies for tasks in real-time systems. It defines real-time systems as systems that must respond to inputs within a specified time period. It describes different types of tasks (periodic, aperiodic, sporadic) and characteristics of real-time systems like determinism and responsiveness. It also summarizes common scheduling algorithms for real-time tasks like cyclic executive, rate monotonic scheduling, earliest deadline first scheduling and compares static priority versus dynamic priority scheduling.
Resource Management in (Embedded) Real-Time Systemsjeronimored
Rate monotonic analysis provides techniques for analyzing real-time systems with periodic tasks. It focuses on ensuring tasks meet deadlines through priority-based scheduling, where the highest priority is given to the task with the shortest period. The utilization bound test determines if a set of periodic tasks will always meet deadlines based on the total utilization being below a limit that depends on the number of tasks.
The document discusses embedded computing systems and outlines some key points:
- Embedded systems are part of larger systems that perform specific functions in constrained, reactive environments using a combination of hardware and software.
- They have real-time requirements and challenges include high complexity, distributed networks, and meeting deadlines with increasing functionality.
- Embedded systems come in many forms, from automotive and industrial control systems to wireless sensor networks and systems within the human body.
This document provides an overview of embedded systems and real-time systems. It discusses embedded software characteristics including responsiveness in real-time. Common architectural patterns for embedded systems like observe and react, environmental control, and process pipeline are described. The document also covers timing analysis, real-time operating systems components, and non-stop system components to ensure continuous operation.
The document provides an introduction to data structures and algorithms analysis. It discusses that a program consists of organizing data in a structure and a sequence of steps or algorithm to solve a problem. A data structure is how data is organized in memory and an algorithm is the step-by-step process. It describes abstraction as focusing on relevant problem properties to define entities called abstract data types that specify what can be stored and operations performed. Algorithms transform data structures from one state to another and are analyzed based on their time and space complexity.
Batteries -Introduction – Types of Batteries – discharging and charging of battery - characteristics of battery –battery rating- various tests on battery- – Primary battery: silver button cell- Secondary battery :Ni-Cd battery-modern battery: lithium ion battery-maintenance of batteries-choices of batteries for electric vehicle applications.
Fuel Cells: Introduction- importance and classification of fuel cells - description, principle, components, applications of fuel cells: H2-O2 fuel cell, alkaline fuel cell, molten carbonate fuel cell and direct methanol fuel cells.
Use PyCharm for remote debugging of WSL on a Windo cf5c162d672e4e58b4dde5d797...shadow0702a
This document serves as a comprehensive step-by-step guide on how to effectively use PyCharm for remote debugging of the Windows Subsystem for Linux (WSL) on a local Windows machine. It meticulously outlines several critical steps in the process, starting with the crucial task of enabling permissions, followed by the installation and configuration of WSL.
The guide then proceeds to explain how to set up the SSH service within the WSL environment, an integral part of the process. Alongside this, it also provides detailed instructions on how to modify the inbound rules of the Windows firewall to facilitate the process, ensuring that there are no connectivity issues that could potentially hinder the debugging process.
The document further emphasizes on the importance of checking the connection between the Windows and WSL environments, providing instructions on how to ensure that the connection is optimal and ready for remote debugging.
It also offers an in-depth guide on how to configure the WSL interpreter and files within the PyCharm environment. This is essential for ensuring that the debugging process is set up correctly and that the program can be run effectively within the WSL terminal.
Additionally, the document provides guidance on how to set up breakpoints for debugging, a fundamental aspect of the debugging process which allows the developer to stop the execution of their code at certain points and inspect their program at those stages.
Finally, the document concludes by providing a link to a reference blog. This blog offers additional information and guidance on configuring the remote Python interpreter in PyCharm, providing the reader with a well-rounded understanding of the process.
Comparative analysis between traditional aquaponics and reconstructed aquapon...bijceesjournal
The aquaponic system of planting is a method that does not require soil usage. It is a method that only needs water, fish, lava rocks (a substitute for soil), and plants. Aquaponic systems are sustainable and environmentally friendly. Its use not only helps to plant in small spaces but also helps reduce artificial chemical use and minimizes excess water use, as aquaponics consumes 90% less water than soil-based gardening. The study applied a descriptive and experimental design to assess and compare conventional and reconstructed aquaponic methods for reproducing tomatoes. The researchers created an observation checklist to determine the significant factors of the study. The study aims to determine the significant difference between traditional aquaponics and reconstructed aquaponics systems propagating tomatoes in terms of height, weight, girth, and number of fruits. The reconstructed aquaponics system’s higher growth yield results in a much more nourished crop than the traditional aquaponics system. It is superior in its number of fruits, height, weight, and girth measurement. Moreover, the reconstructed aquaponics system is proven to eliminate all the hindrances present in the traditional aquaponics system, which are overcrowding of fish, algae growth, pest problems, contaminated water, and dead fish.
Introduction- e - waste – definition - sources of e-waste– hazardous substances in e-waste - effects of e-waste on environment and human health- need for e-waste management– e-waste handling rules - waste minimization techniques for managing e-waste – recycling of e-waste - disposal treatment methods of e- waste – mechanism of extraction of precious metal from leaching solution-global Scenario of E-waste – E-waste in India- case studies.
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1. Real Time System (RTS)
The Islamic University
Department of
Computer Technical Engineering
Third Class
Lecturer
Asst. Lec. Karrar Shakir Muttair ALNomani
المحاضرهاالولى
(النظري)
2019-2020
2. Contents
Concepts of Real time Systems (RTS)
Characteristics of RTS
Types of RTS
Comparison between Types of RTS
Applications of RTS
Challenges of RTS
2
3. Concepts of Real time Systems(RTS)
3
Real-time is a quantitative notion of time measured using a physical clock.
Example: After a certain event occurs (temperature exceeds 50 degrees) the
corresponding action (coolant shower) must complete within 100 mSec.
System: As system is a mapping of a set of inputs into a set of outputs. When the
internal details of the system are not of interest, the mapping function can be
considered as a black box with one or more inputs entering and one or more
outputs existing the system Figure 1.1.
Figure 1.1: A system with (n) inputs and (m) outputs.
4. 4
Terms Associated with RTS
The response-time is the time between the presentation of a set of inputs to
a system and the realization of the required behavior, including the availability of
all associated outputs, is called the response time of the system.
A real-time system must satisfy response-time constraints or risk severe
consequences.
A failed system is a system that cannot satisfy one or more of the
requirements stipulated in the formal system specification.
Real time system means that the system is subjected to real time, i.e.,
response should be guaranteed within a specified timing constraint or system
should meet the specified deadline. For example: flight control system, real time
monitors etc.
Concepts of Real time Systems(RTS)
5. 5
Job : A job is a small piece of work that can be assigned to a processor and
may or may not require resources.
Tasks: A set of related jobs that jointly provide some system functionality.
Release time of a job: It is the time at which job becomes ready for execution.
Execution time of a job: It is the time taken by job to finish its execution.
Deadline of a job: It is the time by which a job should finish its execution.
Deadline is of two types:
1. Relative deadline: Deadline - Release time.
2. Absolute deadline is equal to its relative deadline plus its release time.
Absolute deadline= release time + relative deadline
Response time of a job: It is the length of time from release time of a job to
the instant when it finishes (Completion time).
Response time of a job= Completion time - Release time
Terms Associated with RTS
6. 6
Terms Associated with RTS
Released time = 3
Relative deadline = Deadline - Release time
= 10 – 3 = 7
Absolute deadline = release time + relative deadline
= 3 + 7 = 10
Response time = Completion time - Release time
= 9 – 3 = 6
Figure 1. 2: Descriptive example for some terms of RTS.
7. A Basic Model of RTS
7
Figure 1. 3: A Physical Model of a Real-Time System.
Figure 1. 4: A Model of a Real-Time System.
8. A Basic Model of RTS
8
Sensor: A sensor converts some physical characteristic of its environment into
electrical signals. An example of a sensor is a photo-voltaic cell which converts light
energy into electrical energy.
Actuator: An actuator is any device that takes its inputs from the output interface of a
computer and converts these electrical signals into some physical actions on its
environment. The physical actions may be in the form of motion, change thermal,
electrical. A popular actuator is a motors, heaters or pneumatic.
Signal Condition Units: The electrical signals produced by a computer can rarely be
used to directly drive an actuator. The computer signals usually need conditioning before
the can be used the actuator. This is termed output conditioning. Similarly, input
conditioning is required to be carried out on sensor signal before they can be accepted
by the computer this is termed input conditioning.
Interface Unit: The interface takes care of buffering and the handshake control
aspects. Analog to digital conversion are used in input interface and digital to analog
conversion are used in an output interface.
9. Overall Structure of RTS
9
AS shown on the Figure 1.5 the overall structure of RTS consists of:
Hardware: (CPU, I/O devices, memory… etc.)
A real time Operating System: function as standard OS, with predictable
behavior and well-defined functionality.
A collection of RT tasks/processes: (share resources, communicate/
synchronize with each other and the environment).
Figure 1.5: Overall structure of RTS.
10. Characteristics of RTS
10
1. Time constraints.
2. New Correctness Criterion.
3. Embedded.
4. Safety-Reliability.
5. Concurrency.
6. Distributed and Feedback Structure.
7. Task Criticality.
8. Custom Hardware.
9. Reactive.
10. Stability.
11. Exception Handling.
11. Important Characteristics
11
1.Safety
2.Reliability
Safety and reliability are related but distinct.
1. Safety is concerned with ensuring system cannot cause damage irrespective
of whether or not it conforms to its specification.
2. Reliability is concerned with conformance to a given specification and
delivery of service.
A safe system:
• Does not cause damage even when it fails.
A reliable system:
• Operates for long time without any failure.
12. Types of Real-Time Systems
12
Real-time systems are different from other systems:
Tasks have deadlines associated with them.
A real-time task can be classified into either hard, soft, or firm real-
time task depending on the consequences of a task missing its
deadline.
1. Hard real-time systems
2. Soft real-time systems
3. Firm real-time systems
13. 13
Hard Real-Time Systems
Time is very important and achieving the desired result is also important.
But if the target is achieved without time commitment, it means system
failure.
Many of these systems are considered to be safety critical.
An exceeds in response time leads to potential loss of life and/or big
financial damage.
Sometimes they are “only” mission critical, with the mission being very
expensive. In general there is a cost function associated with the system.
Hard Real-Time System Examples
Car airbag.
Anti lock breaking system (ABS).
Air craft control system.
14. Soft Real-Time Systems
14
There are time limits, but they can be tolerated.
The mistakes here do not lead to the damage of the system. And do not cause
a disaster.
There is a cost associated to overrunning, but this cost may be abstract.
Often connected to Quality-of-Service (QoS).
Soft Real-Time Systems
Video processing.
Digital camera.
Mobile phones.
15. 15
Comparison between Hard RTS and Soft RTS
Characteristics Hard RTS Soft RTS
Response Time Hard- Required Soft - Required
Peak Load Performance Predictable Degraded
Controlled by Environment Computer
Safety Critical Non Critical
Size of Data Small Large
Error Detection Autonomous User Assisted
Hard RTS Vs. Soft RTS
16. 16
Firm Real-Time System
Systems which are soft real-time but in which there is no benefit from late
delivery of service (which means a few missed deadlines will not lead to total
failure, but missing more than a few may lead to complete and catastrophic
system failure).
The computation is obsolete if the job is not finished on time.
Cost may be interpreted as loss of revenue.
Typical example are prediction systems.
Firm Real-Time System Examples
Video conferencing.
Satellite-based tracking of enemy movements.
17. Applications of RTS
17
Metal industry applications (Mechanical and Manufacturing Engineering).
Electric utility monitoring and control applications (Electrical Power Engineering).
Water plants applications (Civil and Environmental Engineering).
Aviation and space applications (Aeronautical Engineering).
Data Communication Applications (Electrical and Computer Engineering).
Petrochemical applications (Chemical Engineering, Petroleum
Engineering).
18. 18
Applications of RTS
Figure 1.6: Disciplines that impact on Real Time System Engineering
Real-Time
Systems
Control
Theory
Programming
Languages
Operations
Research
Algorithms
Queuing
Theory
Operating
Systems
Software
Engineering
Computer
Architecture
Data
Structures
19. Challenges of RTS
The design and implementation of real-time systems requires attention to numerous
problems. These include:
1. The selection of hardware and software.
2. Determine specification and design of real-time systems and correct
representation of temporal behavior.
3. Understanding the nuances of the programming language (s) and the real
time implications resulting from their translation into machine code.
4. Maximizing of system fault tolerance and reliability through careful
design.
5. The design and administration of tests.
6. Finally, measuring and predicting response time and reducing it.
19