as requested and identifies the 3 main points from the document in concise sentences: understanding process management, understanding semaphores, and inter process communication.
MC0085 – Advanced Operating Systems - Master of Computer Science - MCA - SMU DEAravind NC
This document contains 5 questions related to advanced operating systems. Question 1 defines message passing systems and discusses their desirable features such as simplicity, efficiency, reliability, correctness, flexibility and security. Question 2 discusses remote procedure calls (RPC) and how they allow remote subroutine execution. It explains the sequence of events during an RPC including client/server stubs and message passing. Question 3 covers distributed shared memory including memory coherence models, implementation strategies, and centralized server algorithms. Question 4 discusses resource management approaches like task assignment, load balancing, and load sharing. Question 5 outlines challenges in distributed file systems like transparency, flexibility, reliability and performance, and discusses client and server perspectives on file services and access semantics.
The document provides an overview of parallel programming using MPI and OpenMP. It discusses key concepts of MPI including message passing, blocking and non-blocking communication, and collective communication operations. It also covers OpenMP parallel programming model including shared memory model, fork/join parallelism, parallel for loops, and shared/private variables. The document is intended as lecture material for an introduction to high performance computing using MPI and OpenMP.
The document discusses various performance measures for parallel computing including speedup, efficiency, Amdahl's law, and Gustafson's law. Speedup is defined as the ratio of sequential to parallel execution time. Efficiency is defined as speedup divided by the number of processors. Amdahl's law provides an upper bound on speedup based on the fraction of sequential operations, while Gustafson's law estimates speedup based on the fraction of time spent in serial code for a fixed problem size on varying processors. Other topics covered include performance bottlenecks, data races, data race avoidance techniques, and deadlock avoidance using virtual channels.
The document discusses principles of concurrency in operating systems, including mutual exclusion and synchronization. It covers various techniques for managing concurrent processes such as hardware support using interrupt disabling or compare-and-swap instructions. It also covers higher-level synchronization methods like semaphores, monitors, and message passing. It provides examples of how these techniques can solve concurrency issues like the bounded buffer problem and readers-writers problem.
The document discusses various techniques for implementing subprograms in programming languages. It covers:
1) The general semantics of calls and returns between subprograms and the actions involved.
2) Implementing simple subprograms with static local variables and activation records.
3) Implementing subprograms with stack-dynamic local variables using run-time stacks and activation records.
4) Techniques for implementing nested subprograms using static linking chains to access nonlocal variables.
This document discusses priority queuing, which assigns different priority levels to packets in a queue to address impatient customers. It describes how priority can be determined by packet headers, source/destination addresses, ports, or other criteria. The document outlines preemptive and non-preemptive priority queuing, provides state transition diagrams and performance measures, and gives an example comparing FCFS, preemptive priority, and non-preemptive priority queuing for a router handling video and audio packets.
This document discusses data replication in distributed systems. It describes two types of replication: synchronous and asynchronous. For asynchronous replication, there is primary site asynchronous and peer-to-peer asynchronous. The document then focuses on the lazy master framework, outlining components like the primary/secondary copies, ownership, propagation, refreshment, and configuration. It provides details on the system architecture involving log monitors, propagators, receivers, and refreshers. Finally, it covers topics like failure and recovery handling.
Practical byzantine fault tolerance by altanaiALTANAI BISHT
Byzantine Fault Tolerance
state machine replication algorithm that is safe in asynchronous systems such as the Internet.Used to build highly available systems
incorporates mechanisms to defend against Byzantine-faulty clients
BFT provides safety and liveness if fewer than 1/3 of the replicas fail during the lifetime of the
system
Recovers replicas proactively : provided fewer than 1/3 of the replicas become faulty within a
small window of vulnerability
3f+1 replicas to survive the failures
3 phases protocol (pre-prepare, prepare, and commit)
Uses cryptographic hash function to compute message digests
And message authentication codes (MACs) to authenticate all messages
Allow for a very strong adversary
MC0085 – Advanced Operating Systems - Master of Computer Science - MCA - SMU DEAravind NC
This document contains 5 questions related to advanced operating systems. Question 1 defines message passing systems and discusses their desirable features such as simplicity, efficiency, reliability, correctness, flexibility and security. Question 2 discusses remote procedure calls (RPC) and how they allow remote subroutine execution. It explains the sequence of events during an RPC including client/server stubs and message passing. Question 3 covers distributed shared memory including memory coherence models, implementation strategies, and centralized server algorithms. Question 4 discusses resource management approaches like task assignment, load balancing, and load sharing. Question 5 outlines challenges in distributed file systems like transparency, flexibility, reliability and performance, and discusses client and server perspectives on file services and access semantics.
The document provides an overview of parallel programming using MPI and OpenMP. It discusses key concepts of MPI including message passing, blocking and non-blocking communication, and collective communication operations. It also covers OpenMP parallel programming model including shared memory model, fork/join parallelism, parallel for loops, and shared/private variables. The document is intended as lecture material for an introduction to high performance computing using MPI and OpenMP.
The document discusses various performance measures for parallel computing including speedup, efficiency, Amdahl's law, and Gustafson's law. Speedup is defined as the ratio of sequential to parallel execution time. Efficiency is defined as speedup divided by the number of processors. Amdahl's law provides an upper bound on speedup based on the fraction of sequential operations, while Gustafson's law estimates speedup based on the fraction of time spent in serial code for a fixed problem size on varying processors. Other topics covered include performance bottlenecks, data races, data race avoidance techniques, and deadlock avoidance using virtual channels.
The document discusses principles of concurrency in operating systems, including mutual exclusion and synchronization. It covers various techniques for managing concurrent processes such as hardware support using interrupt disabling or compare-and-swap instructions. It also covers higher-level synchronization methods like semaphores, monitors, and message passing. It provides examples of how these techniques can solve concurrency issues like the bounded buffer problem and readers-writers problem.
The document discusses various techniques for implementing subprograms in programming languages. It covers:
1) The general semantics of calls and returns between subprograms and the actions involved.
2) Implementing simple subprograms with static local variables and activation records.
3) Implementing subprograms with stack-dynamic local variables using run-time stacks and activation records.
4) Techniques for implementing nested subprograms using static linking chains to access nonlocal variables.
This document discusses priority queuing, which assigns different priority levels to packets in a queue to address impatient customers. It describes how priority can be determined by packet headers, source/destination addresses, ports, or other criteria. The document outlines preemptive and non-preemptive priority queuing, provides state transition diagrams and performance measures, and gives an example comparing FCFS, preemptive priority, and non-preemptive priority queuing for a router handling video and audio packets.
This document discusses data replication in distributed systems. It describes two types of replication: synchronous and asynchronous. For asynchronous replication, there is primary site asynchronous and peer-to-peer asynchronous. The document then focuses on the lazy master framework, outlining components like the primary/secondary copies, ownership, propagation, refreshment, and configuration. It provides details on the system architecture involving log monitors, propagators, receivers, and refreshers. Finally, it covers topics like failure and recovery handling.
Practical byzantine fault tolerance by altanaiALTANAI BISHT
Byzantine Fault Tolerance
state machine replication algorithm that is safe in asynchronous systems such as the Internet.Used to build highly available systems
incorporates mechanisms to defend against Byzantine-faulty clients
BFT provides safety and liveness if fewer than 1/3 of the replicas fail during the lifetime of the
system
Recovers replicas proactively : provided fewer than 1/3 of the replicas become faulty within a
small window of vulnerability
3f+1 replicas to survive the failures
3 phases protocol (pre-prepare, prepare, and commit)
Uses cryptographic hash function to compute message digests
And message authentication codes (MACs) to authenticate all messages
Allow for a very strong adversary
This document summarizes key concepts from Chapter 12 of the distributed systems textbook. It covers coordination and agreement problems in distributed systems, including distributed mutual exclusion, elections to choose a unique process, multicast communication, and the consensus problem. Algorithms discussed include a central server algorithm, ring-based algorithm, and algorithm using logical clocks for distributed mutual exclusion. Maekawa's voting algorithm for mutual exclusion is also summarized.
A Beginner’s Guide to Programming Logic, Introductory
Chapter 2
Working with Data, Creating Modules, and Designing High-Quality Programs
Objectives
In this chapter, you will learn about:
- Declaring and using variables and constants
- Assigning values to variables
- The advantages of modularization
- Modularizing a program
- The most common configuration for mainline logic
COURSE TECHNOLOGY
CENGAGE Learning
The document discusses the phases of a compiler. It describes the eight main phases as lexical analysis, syntax analysis, semantic analysis, intermediate code generation, code optimization, code generation, symbol table management, and error handling. The first six phases comprise the formal phases and transform the source code through various representations. The last two phases are informal but support the formal phases. The document also provides details on the symbol table manager, describing it as a data structure that stores attributes of identifiers used during compilation.
Global state recording in Distributed SystemsArsnet
This document describes algorithms for recording consistent global states (snapshots) in distributed systems. It discusses models of communication, system models, and issues in recording global states. It then summarizes the Spezialetti-Kearns algorithm for FIFO systems, which uses markers to distinguish messages to include in snapshots. For non-FIFO systems, it covers the Lai-Yang algorithm using message coloring and Mattern's algorithm based on vector clocks.
This document discusses hardware and software parallelism in computer architecture. It defines hardware parallelism as the number of instruction issues per machine cycle that a processor can handle, such as a 3-issue processor. Software parallelism comes from aspects of the algorithm, programming style, and program design, and can be seen from the program flow graph. Mismatch can occur between hardware and software parallelism. Examples show how a program with higher software than hardware parallelism would take longer on a processor, and how adding more processors reduces cycle time. The mismatch problem can be addressed by improving compilation or redesigning hardware.
Chapter 1 - An Overview of Computers and Programming LanguagesAdan Hubahib
The document summarizes a chapter in a textbook on Java programming. It discusses the history of computers, the hardware and software components of a computer system, programming languages, how Java programs are processed, problem-solving techniques, and structured and object-oriented programming methodologies. The chapter objectives are listed at the beginning and key concepts are defined and explained throughout with figures.
This document discusses subprograms (also called subroutines) in programming languages. It covers:
- The basic definitions and characteristics of subprograms, including headers, parameters, and local variables.
- Different parameter passing methods like pass-by-value, pass-by-reference, and their implementation in common languages.
- Additional features of subprograms including overloading, generics, and functions passing subprograms as parameters.
The compilation process consists of multiple phases that each take the output from the previous phase as input. The phases are: lexical analysis, syntax analysis, semantic analysis, intermediate code generation, code optimization, and code generation.
The analysis phase consists of three sub-phases: lexical analysis, syntax analysis, and semantic analysis. Lexical analysis converts the source code characters into tokens. Syntax analysis constructs a parse tree from the tokens. Semantic analysis checks that the program instructions are valid for the programming language.
The entire compilation process takes the source code as input and outputs the target program after multiple analysis and synthesis phases.
A macro processor is a system software. Macro is that the Section of code that the programmer writes (defines) once, and then can use or invokes many times.
This document discusses subprograms and parameters in programming languages. It covers:
1. Characteristics of subprograms like having a single entry point and control returning to the caller.
2. Definitions related to subprograms like subprogram definitions, calls, headers, and parameters.
3. Issues with parameter passing like positional vs keyword parameters, default values, and different passing methods.
4. Design considerations for subprograms like parameter types, local variables, nested and overloaded subprograms, and independent compilation.
The document discusses various algorithms for achieving distributed mutual exclusion and process synchronization in distributed systems. It covers centralized, token ring, Ricart-Agrawala, Lamport, and decentralized algorithms. It also discusses election algorithms for selecting a coordinator process, including the Bully algorithm. The key techniques discussed are using logical clocks, message passing, and quorums to achieve mutual exclusion without a single point of failure.
The document discusses the history and development of the MPI standard for parallel programming. It describes how MPI was developed in the early 1990s to create a common standard for message passing programming that could unite the various proprietary interfaces that existed at the time. The first MPI standard was released in 1994 after several years of development and input from vendors, national labs, and researchers. MPI was quickly adopted due to a reference implementation and its ability to provide a portable abstraction while allowing for high-performance implementations.
This document discusses key concepts related to variables in programming languages including names, bindings, scopes, and lifetimes. It covers different types of variables such as static, stack dynamic, and heap dynamic variables. It also compares static and dynamic scoping models and how they determine variable visibility. The referencing environment is defined as the collection of all visible variables for a given statement.
This document discusses message passing architectures. The key points are:
1) Message passing architectures allow processors to communicate data without a global memory by sending messages. Each processor has local memory and communicates via messages.
2) Important factors in message passing networks are link bandwidth and network latency.
3) Processes running on different processors use external channels to exchange messages, while processes on the same processor use internal channels. This avoids the need for synchronization.
This document summarizes topics related to distributed mutual exclusion and algorithms for coordinating processes to ensure only one can access a shared resource at a time. It describes essential requirements for mutual exclusion including safety, liveness, and ordering. It then summarizes several algorithms for distributed mutual exclusion including a central server algorithm, ring-based algorithm, multicast-based algorithm using logical clocks, and Maekawa's voting algorithm. For each algorithm, it highlights how the requirements are satisfied and discusses performance factors like bandwidth consumption and throughput.
The document discusses the Practical Byzantine Fault Tolerance (PBFT) algorithm. PBFT is a consensus algorithm that allows a distributed system to tolerate Byzantine faults. It replicates services across multiple servers and uses a three-phase protocol (pre-prepare, prepare, commit) to ensure replicas apply requests in the same order. PBFT can tolerate up to f faulty replicas as long as there are 2f+1 total replicas. The algorithm guarantees safety by ensuring all non-faulty replicas agree on a total order of requests, and liveness by allowing the system to make progress even if the primary replica fails.
The document discusses the phases of a compiler and how a program is processed. It explains that a source program goes through multiple phases including lexical analysis, syntax analysis, semantic analysis, intermediate code generation, optimization, and code generation to produce target machine code. The compiler performs analysis and synthesis to process the source code in 6 main phases and generate executable code from the input source code.
The document discusses the phases of a compiler, which are typically divided into analysis and synthesis phases. The analysis phase includes lexical analysis, syntax analysis, and semantic analysis. The synthesis phase includes intermediate code generation, code optimization, and code generation. Other topics discussed include symbol tables, error handlers, examples of common compilers, and reasons for learning about compilers.
This document discusses implementing a parallel merge sort algorithm using MPI (Message Passing Interface). It describes the background of MPI and how it can be used for communication between processes. It provides details on the dataset used, MPI functions for initialization, communication between processes, and summarizes the results which show a decrease in runtime when increasing the number of processors.
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.
This document discusses various methods of interprocess communication (IPC). It describes two main models of IPC - shared memory and message passing. Several IPC mechanisms are then explained in detail, including pipes, signals, semaphores, sockets, shared memory, message queues, and potential issues like deadlocks that can arise with improper synchronization.
This document summarizes key concepts from Chapter 12 of the distributed systems textbook. It covers coordination and agreement problems in distributed systems, including distributed mutual exclusion, elections to choose a unique process, multicast communication, and the consensus problem. Algorithms discussed include a central server algorithm, ring-based algorithm, and algorithm using logical clocks for distributed mutual exclusion. Maekawa's voting algorithm for mutual exclusion is also summarized.
A Beginner’s Guide to Programming Logic, Introductory
Chapter 2
Working with Data, Creating Modules, and Designing High-Quality Programs
Objectives
In this chapter, you will learn about:
- Declaring and using variables and constants
- Assigning values to variables
- The advantages of modularization
- Modularizing a program
- The most common configuration for mainline logic
COURSE TECHNOLOGY
CENGAGE Learning
The document discusses the phases of a compiler. It describes the eight main phases as lexical analysis, syntax analysis, semantic analysis, intermediate code generation, code optimization, code generation, symbol table management, and error handling. The first six phases comprise the formal phases and transform the source code through various representations. The last two phases are informal but support the formal phases. The document also provides details on the symbol table manager, describing it as a data structure that stores attributes of identifiers used during compilation.
Global state recording in Distributed SystemsArsnet
This document describes algorithms for recording consistent global states (snapshots) in distributed systems. It discusses models of communication, system models, and issues in recording global states. It then summarizes the Spezialetti-Kearns algorithm for FIFO systems, which uses markers to distinguish messages to include in snapshots. For non-FIFO systems, it covers the Lai-Yang algorithm using message coloring and Mattern's algorithm based on vector clocks.
This document discusses hardware and software parallelism in computer architecture. It defines hardware parallelism as the number of instruction issues per machine cycle that a processor can handle, such as a 3-issue processor. Software parallelism comes from aspects of the algorithm, programming style, and program design, and can be seen from the program flow graph. Mismatch can occur between hardware and software parallelism. Examples show how a program with higher software than hardware parallelism would take longer on a processor, and how adding more processors reduces cycle time. The mismatch problem can be addressed by improving compilation or redesigning hardware.
Chapter 1 - An Overview of Computers and Programming LanguagesAdan Hubahib
The document summarizes a chapter in a textbook on Java programming. It discusses the history of computers, the hardware and software components of a computer system, programming languages, how Java programs are processed, problem-solving techniques, and structured and object-oriented programming methodologies. The chapter objectives are listed at the beginning and key concepts are defined and explained throughout with figures.
This document discusses subprograms (also called subroutines) in programming languages. It covers:
- The basic definitions and characteristics of subprograms, including headers, parameters, and local variables.
- Different parameter passing methods like pass-by-value, pass-by-reference, and their implementation in common languages.
- Additional features of subprograms including overloading, generics, and functions passing subprograms as parameters.
The compilation process consists of multiple phases that each take the output from the previous phase as input. The phases are: lexical analysis, syntax analysis, semantic analysis, intermediate code generation, code optimization, and code generation.
The analysis phase consists of three sub-phases: lexical analysis, syntax analysis, and semantic analysis. Lexical analysis converts the source code characters into tokens. Syntax analysis constructs a parse tree from the tokens. Semantic analysis checks that the program instructions are valid for the programming language.
The entire compilation process takes the source code as input and outputs the target program after multiple analysis and synthesis phases.
A macro processor is a system software. Macro is that the Section of code that the programmer writes (defines) once, and then can use or invokes many times.
This document discusses subprograms and parameters in programming languages. It covers:
1. Characteristics of subprograms like having a single entry point and control returning to the caller.
2. Definitions related to subprograms like subprogram definitions, calls, headers, and parameters.
3. Issues with parameter passing like positional vs keyword parameters, default values, and different passing methods.
4. Design considerations for subprograms like parameter types, local variables, nested and overloaded subprograms, and independent compilation.
The document discusses various algorithms for achieving distributed mutual exclusion and process synchronization in distributed systems. It covers centralized, token ring, Ricart-Agrawala, Lamport, and decentralized algorithms. It also discusses election algorithms for selecting a coordinator process, including the Bully algorithm. The key techniques discussed are using logical clocks, message passing, and quorums to achieve mutual exclusion without a single point of failure.
The document discusses the history and development of the MPI standard for parallel programming. It describes how MPI was developed in the early 1990s to create a common standard for message passing programming that could unite the various proprietary interfaces that existed at the time. The first MPI standard was released in 1994 after several years of development and input from vendors, national labs, and researchers. MPI was quickly adopted due to a reference implementation and its ability to provide a portable abstraction while allowing for high-performance implementations.
This document discusses key concepts related to variables in programming languages including names, bindings, scopes, and lifetimes. It covers different types of variables such as static, stack dynamic, and heap dynamic variables. It also compares static and dynamic scoping models and how they determine variable visibility. The referencing environment is defined as the collection of all visible variables for a given statement.
This document discusses message passing architectures. The key points are:
1) Message passing architectures allow processors to communicate data without a global memory by sending messages. Each processor has local memory and communicates via messages.
2) Important factors in message passing networks are link bandwidth and network latency.
3) Processes running on different processors use external channels to exchange messages, while processes on the same processor use internal channels. This avoids the need for synchronization.
This document summarizes topics related to distributed mutual exclusion and algorithms for coordinating processes to ensure only one can access a shared resource at a time. It describes essential requirements for mutual exclusion including safety, liveness, and ordering. It then summarizes several algorithms for distributed mutual exclusion including a central server algorithm, ring-based algorithm, multicast-based algorithm using logical clocks, and Maekawa's voting algorithm. For each algorithm, it highlights how the requirements are satisfied and discusses performance factors like bandwidth consumption and throughput.
The document discusses the Practical Byzantine Fault Tolerance (PBFT) algorithm. PBFT is a consensus algorithm that allows a distributed system to tolerate Byzantine faults. It replicates services across multiple servers and uses a three-phase protocol (pre-prepare, prepare, commit) to ensure replicas apply requests in the same order. PBFT can tolerate up to f faulty replicas as long as there are 2f+1 total replicas. The algorithm guarantees safety by ensuring all non-faulty replicas agree on a total order of requests, and liveness by allowing the system to make progress even if the primary replica fails.
The document discusses the phases of a compiler and how a program is processed. It explains that a source program goes through multiple phases including lexical analysis, syntax analysis, semantic analysis, intermediate code generation, optimization, and code generation to produce target machine code. The compiler performs analysis and synthesis to process the source code in 6 main phases and generate executable code from the input source code.
The document discusses the phases of a compiler, which are typically divided into analysis and synthesis phases. The analysis phase includes lexical analysis, syntax analysis, and semantic analysis. The synthesis phase includes intermediate code generation, code optimization, and code generation. Other topics discussed include symbol tables, error handlers, examples of common compilers, and reasons for learning about compilers.
This document discusses implementing a parallel merge sort algorithm using MPI (Message Passing Interface). It describes the background of MPI and how it can be used for communication between processes. It provides details on the dataset used, MPI functions for initialization, communication between processes, and summarizes the results which show a decrease in runtime when increasing the number of processors.
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.
This document discusses various methods of interprocess communication (IPC). It describes two main models of IPC - shared memory and message passing. Several IPC mechanisms are then explained in detail, including pipes, signals, semaphores, sockets, shared memory, message queues, and potential issues like deadlocks that can arise with improper synchronization.
Processes communicate through interprocess communication (IPC) using two main models: shared memory and message passing. Shared memory allows processes to access the same memory regions, while message passing involves processes exchanging messages through mechanisms like mailboxes, pipes, signals, and sockets. Common IPC techniques include semaphores, shared memory, message queues, and sockets that allow processes to synchronize actions and share data in both blocking and non-blocking ways. Deadlocks can occur if processes form a circular chain while waiting for resources held by other processes.
In 1965, Dijkstra proposed a new and very significant technique for managing concurrent processes by using the value of a simple integer variable to synchronize the progress of interacting processes.
This integer variable is called semaphore. So it is basically a synchronizing tool and is accessed only through two low standard atomic operations, wait and signal designated by P() and V() respectively.
The classical definition of wait and signal are :
Wait : decrement the value of its argument S as soon as it would become non-negative.
Signal : increment the value of its argument, S as an individual operation.
Inter-process communication (IPC) allows processes to communicate and synchronize actions. There are two main models - shared memory, where processes directly read/write shared memory, and message passing, where processes communicate by sending and receiving messages. Critical sections are parts of code that access shared resources and must be mutually exclusive to avoid race conditions. Semaphores can be used to achieve mutual exclusion, with operations P() and V() that decrement or increment the semaphore value to control access to the critical section. For example, in the producer-consumer problem semaphores can suspend producers if the buffer is full and consumers if empty, allowing only one process at a time in the critical section.
This document provides an overview of interprocess communication (IPC) structures. It discusses pipes, which allow for one-directional data flow between related processes using file descriptors. It also covers FIFOs which are similar to pipes but use pathnames and can be accessed by unrelated processes. The document outlines the main XSI IPC structures - message queues for communication via linked lists of messages, semaphores for controlling access to shared resources, and shared memory for processes to access the same memory region. It provides details on how each IPC structure is created, accessed, and removed in UNIX systems.
1. The document provides an overview of the history and development of UNIX/Linux operating systems. It originated from projects in the 1960s and was further developed by Ken Thompson, Dennis Ritchie and others.
2. UNIX became popular due to its modular design, use of a hierarchical file system, treating all system resources as files, and ability to combine simple programs together.
3. The basic architecture of UNIX involves application programs interacting with the kernel via system calls to perform tasks like process and memory management.
Thread vs Process
scheduling
synchronization
The thread begins execution with the C/C run-time library startup code.
The startup code calls your main or WinMain and execution continues until the main function returns and the C/C library code calls ExitProcess.
Reflection is the ability of a managed code to read its own metadata for the purpose of finding assemblies, modules and type information at runtime. The classes that give access to the metadata of a running program are in System.Reflection.
System.Reflection namespace defines the following types to analyze the module's metadata of an assembly:
Assembly, Module, Enum, ParameterInfo, MemberInfo, Type, MethodInfo, ConstructorInfo, FieldInfo, EventInfo, and PropertyInfo
Presentation - Programming a Heterogeneous Computing ClusterAashrith Setty
This document provides an overview of programming a heterogeneous computing cluster using the Message Passing Interface (MPI). It begins with background on heterogeneous computing and MPI. It then discusses the MPI programming model and environment management routines. A vector addition example is presented to demonstrate an MPI implementation. Point-to-point and collective communication routines are explained. Finally, it covers groups, communicators, and virtual topologies in MPI programming.
This document summarizes three papers presented at an S&P 2012 security conference session on system security. The first paper proposes a framework to eliminate backdoors from response-computable authentication systems. The second paper discusses replacing the standard program loader with a secure loader to prevent attacks on software-based fault isolation. The third paper presents a technique called ReDebug for finding unpatched code clones in entire OS distributions.
Inter-Process Communication in distributed systemsAya Mahmoud
Inter-Process Communication is at the heart of all distributed systems, so we need to know the ways that processes can exchange information.
Communication in distributed systems is based on Low-level message passing as offered by the underlying network.
This document discusses problems that can occur with concurrency, including sharing global resources, locating programming errors, and efficiently locking resources. It also covers solutions to concurrency issues like mutual exclusion using semaphores, monitors, and message passing between processes.
The document discusses basic operating system concepts including resource management, abstraction, and virtualization as main goals of an OS. It describes system calls as entry points for users to request OS services, and some common UNIX system calls. It also reviews key OS concepts like processes, threads, scheduling, synchronization, and memory management.
The objectives of Multithreaded Programming in Operating Systems are:
- To introduce the notion of a thread—a fundamental unit of CPU utilization that forms the basis of multithreaded computer systems.
- To discuss the APIs for the Pthreads, Windows, and Java thread libraries
- To explore several strategies that provide implicit threading.
- To examine issues related to multithreaded programming.
- To cover operating system support for threads in Windows and Linux.
Message Passing, Remote Procedure Calls and Distributed Shared Memory as Com...Sehrish Asif
Message Passing, Remote Procedure Calls and
Distributed Shared Memory as Communication Paradigms for Distributed Systems & Remote Procedure Call Implementation Using Distributed Algorithms
This document discusses multiprogramming and time sharing in operating systems. It defines multiprogramming as allowing multiple programs to execute concurrently by assigning pending work to idle processors and I/O devices. Time sharing extends multiprogramming by rapidly switching between programs so that each program executes for a fixed time quantum, giving users the impression that the entire system is dedicated to their use. The key aspects covered are the concepts of processes, CPU scheduling, and how multiprogramming and time sharing improve resource utilization.
Multiprocessing -Interprocessing communication and process sunchronization,se...Neena R Krishna
This document discusses interprocessor communication and process synchronization. It describes how independent processes can cooperate by exchanging data through interprocessor communication methods like shared memory and message passing. It also explains process synchronization techniques like semaphores, locks, and barriers that allow processes to coordinate access to shared resources and prevent race conditions. The key synchronization methods of semaphores, locks, and barriers are defined and semaphore implementation using wait and signal operations is demonstrated using the classic producer-consumer problem example.
The document discusses the fundamentals of computer systems, including definitions, components, and how they work together. It defines a computer as an electronic device that accepts input, processes it, and provides output. The key components are the input and output units, memory unit, CPU (consisting of the ALU and control unit), and secondary storage. The input and output units send and receive data, the memory unit temporarily stores programs and data, the CPU performs arithmetic/logical operations and coordinates tasks, and secondary storage provides long-term storage. Together these components work to accept user input, process the data, and provide the results.
The document discusses fundamental data types in C including integer, floating point, character, and void types. It describes how variables must be declared before use and explains basic type modifiers like short, long, and unsigned. The summary also covers integer storage sizes and ranges, floating point precision and representation, and type conversions in C using casts and arithmetic promotion.
This document provides an introduction and overview of Hibernate, an object-relational mapping tool for Java. It discusses what ORM is, why it is used, and defines key Hibernate concepts like entities, mapping files, configuration files, and the session factory. It also provides an example of creating a basic Hibernate project with an Employee entity class, mapping file, configuration file, and test case to load an employee object by ID from the database.
The document discusses the benefits of exercise for mental health. Regular physical activity can help reduce anxiety and depression and improve mood and cognitive function. Exercise causes chemical changes in the brain that may help protect against mental illness and improve symptoms.
A JDBC type 2 driver converts JDBC API calls to database driver native API calls. It has a two-tier architecture and is faster than other drivers but is database dependent. A type 4 driver converts JDBC calls to database native network calls. It is platform independent, lightweight, and portable but requires implementing network protocols. A type 3 driver converts JDBC calls to database independent network calls and supports three-tier architectures and distributed transactions.
The document discusses the JDBC API and the basic steps for working with it to access a tabular datastore from a Java application. It covers:
1. The JDBC API provides an abstraction layer for Java programs to access database services via JDBC drivers.
2. The basic steps involve obtaining a database connection, executing SQL statements, and processing the results.
3. Obtaining a connection involves instantiating a Driver object, constructing a JDBC URL to identify the database, and passing this along with authentication properties to the Driver's connect method.
The document discusses obtaining a connection to a database in Java using JDBC. It provides code examples of creating a database connection using the DriverManager class and Oracle's JDBC Thin driver. The code inserts a record into an EMP table for demonstration purposes. Best practices for database connectivity in a Java project are then covered, such as using the DAO pattern to separate data access logic from business logic. This improves testability, reusability and flexibility in switching database types.
The document discusses improving the Data Access Object (DAO) design pattern implementation in a project using JDBC for database connectivity. It describes how the current DAO implementation creates a new Driver object on every request, which is inefficient. It recommends using the DriverManager class instead to manage a single Driver instance and create connections. The DriverManager acts as a factory class to centralize the connection creation code and avoid multiple Driver instances, improving performance.
This document describes an example of using URL rewriting and hidden form fields to maintain client state. The Home page links to a Login page containing a form for a username and password. Submitting the form calls the LoginServlet, which validates the credentials against a database using a UserDAO. If valid, the user is redirected to a personalized page welcoming them by name.
This document discusses three ways to set internal styles in HTML:
1) Universal styles that apply to all instances of a tag throughout the page. For example, making all <font> tags bold.
2) Styles using identifiers that allow restricting styles to specific elements. An ID is added and referenced in the style sheet.
3) User-defined styles that can customize styles.
The examples demonstrate applying a green color to all <a> links universally and then using IDs to style two <a> links differently. Internal styles only affect the current page.
The document discusses HTML elements and their structure. It explains that HTML elements contain a start tag, element content, and end tag. Elements can be nested within other elements. Common elements like <p>, <body>, and <html> are used to demonstrate how elements are structured and nested to form an HTML document. The document also covers empty elements, case sensitivity of tags, and the importance of including closing tags.
Attributes provide additional information about HTML elements. They are specified in name/value pairs within start tags. Attribute names and values are case-insensitive but it is recommended to use lowercase according to W3C standards. Common attributes include class, id, style, and title, and attribute values should always be enclosed in single or double quotes.
This document discusses HTML (Hypertext Markup Language), the most widely used language for creating web pages. It describes what HTML is, how it uses markup tags to provide structure and layout for web content. The document also explains how HTML pages are rendered and displayed in web browsers, and provides examples of common HTML tags and elements used to create basic HTML documents.
This document provides information on HTML headings, horizontal lines, and comments. It explains that headings are defined using tags from <h1> to <h6>, with <h1> being the most important and <h6> the least important. Horizontal lines are created using the <hr> tag to separate content. HTML comments are written using <!-- and --> and are ignored by browsers.
HTML forms allow users to enter and submit data to a server. The <form> element is used to create an HTML form, which can contain various input elements like text fields, checkboxes, radio buttons, and submit buttons. Common input element types include text, password, radio buttons, checkboxes, and submit buttons. Radio buttons allow a single selection from options, while checkboxes allow zero or more selections. The submit button submits the form data to the action page specified in the form tag.
1. The document provides an overview of CSS (Cascading Style Sheets) and how it can be used to style web pages by applying styles to HTML elements.
2. Styles can be applied inline, via embedded style blocks, or through external style sheets. External style sheets allow controlling styles across entire websites.
3. CSS properties like font, color, size, and other attributes can be set for elements using selectors like element names, classes, IDs to format text. Additional properties control layout aspects like margins, padding, borders.
VIEWs allow users to select subsets of data from one or more tables. A VIEW acts like a virtual table but contains no data itself - it just represents the result set of a SELECT statement. VIEWs provide a layer of security by restricting access to specific rows, columns, or tables. The CREATE VIEW statement is used to define a new VIEW, ALTER VIEW modifies an existing VIEW definition, and DROP VIEW removes a VIEW.
VIEWs allow users to select subsets of data from one or more tables. A VIEW acts like a virtual table but contains no data itself - it just represents the result set of a SELECT statement. VIEWs provide a layer of security by restricting access to specific rows, columns, or tables. The CREATE VIEW statement is used to define a new VIEW, ALTER VIEW modifies an existing VIEW definition, and DROP VIEW removes a VIEW.
VIEWs allow users to select subsets of data from one or more tables. A VIEW acts like a virtual table but contains no data itself - it just represents the result set of a SELECT statement. VIEWs provide a layer of security by restricting access to specific rows, columns, or tables. The CREATE VIEW statement is used to define a new VIEW, ALTER VIEW modifies an existing VIEW definition, and DROP VIEW removes a VIEW.
JDBC allows Java applications to connect to MySQL databases. The document provides instructions to install MySQL, download the MySQL JDBC driver from online, and select the platform-independent ZIP file version of the driver.
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CPP TUTORIALS
2
3. Recap
In last class, you have learnt :
• Multilevel Queue Scheduling
• Types of Queues
• Multilevel Feed Back Queue Scheduling
3
4. Objectives
On completion of this class, you would be able to
know
• Understand Semaphores
• Inter Process Communication
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5. Semaphores
• Semaphore is basically a synchronizing tool
• Used as a solution to critical section problems
What is critical section?
– To control access to shared resources, we declare a
section of code to be critical
– We regulate access to that section
5
6. Semaphores
Example :
• System consisting of n threads {TO, T1…Tn-1}
• Each thread has a segment of code, called “critical section”
• Where the thread may be changing common variables,
updating a table & so on
• Important feature of a system is that, when one thread is
executing in its critical section, no other thread is allowed
to execute in its critical section 6
7. Semaphores
•Semaphore is used to identify whether the operation is to
be executed or the CPU has to wait
• Semaphore is an integer, it is accessed through two
operations ie. wait and signal
• Wait is used to test for operation
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• Signal is used to increment the integer
8. Interprocess Communication
• Inter process communication provides a mechanism
•to allow processes to communicate and to synchronize
their actions
•without sharing the same address space
• IPC is provided by message passing systems
• If a Process want to communicate they must send
message and receive messages from each other via a
communication link existing between them
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10. Interprocess Communication
• This link can be implemented in many ways
– Direct or Indirect communication
– Symmetric or Asymmetric communication
– Automatic or Explicit buffering
– Send a copy directly or Send by reference
– Fixed sized or Variable sized messages
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11. Summary
In this class, you have learnt :
---- Critical Section problem
---- Semaphores
---- Inter Process Communication
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12. Frequently Asked Questions
1. What is a Semaphores?
2. Explain Critical Section problem
3. Explain Inter Process Communication
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14. 1. Semaphore is basically a ---------- tool
a) Critical section
b) A synchronous
c) Synchronizing
d) None
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15. 2. --------- is used to identify whether the operation is
to be executed or the CPU has to wait
a) Critical – Section
b) Semaphore
c) Both
d) None
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16. 3. ---------is provided by message passing systems
a) Critical section
b) Semaphore
c) IPC
d) None
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17. 4. Semaphore is an integer it is accessed through ----
a) IPC
b) Critical section
c) Wait & signal
d) None
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