Operating Systems Chapter 2 PDF

Operatin g Systems: Chapter 2 Internals and Operating Design Principle System Overview Ninth Edition, Global Edition s...

Operatin g Systems: Chapter 2 Internals and Operating Design Principle System Overview Ninth Edition, Global Edition s By William Stallings Copyright © 2018 Pearson Education, Ltd. All Rights Reserved.  Operating System A program that controls the execution of application programs An interface between applications and hardware Main objectives of an OS: Convenience Efficiency Ability to evolve Copyright © 2018 Pearson Education, Ltd. All Rights Reserved. Copyright © 2018 Pearson Education, Ltd. All Rights Reserved.  Operating System Services Program development Program execution Access I/O devices Controlled access to files System access Error detection and response Accounting Copyright © 2018 Pearson Education, Ltd. All Rights Reserved.  Key Interfaces Instruction set architecture (ISA) Application binary interface (ABI) Application programming interface (API) Copyright © 2018 Pearson Education, Ltd. All Rights Reserved.  The Operating System as Resource Manager The OS is responsible for controlling the use of a computer’s resources, such as I/O, main and secondary memory, and processor execution time Copyright © 2018 Pearson Education, Ltd. All Rights Reserved.  Operating System as Resource Manager Functions in the same way as ordinary computer software Program, or suite of programs, executed by the processor Frequently relinquishes control and must depend on the processor to allow it to regain control Copyright © 2018 Pearson Education, Ltd. All Rights Reserved. Copyright © 2018 Pearson Education, Ltd. All Rights Reserved.  Evolution of Operating Systems  A major OS will evolve over time for a number of reasons: Hardware upgrades New types of hardware New services Fixes Copyright © 2018 Pearson Education, Ltd. All Rights Reserved.  Evolution of Operating Systems  Stages include: Time Sharing Multiprogramme Systems d Batch Systems Simple Batch Systems Serial Processin g Copyright © 2018 Pearson Education, Ltd. All Rights Reserved.  Serial Processing Earliest Problems: Computers: Scheduling: No operating system Most installations used a Programmers hardcopy sign-up sheet to interacted directly with reserve computer time the computer hardware Time allocations could run short or Computers ran from a long, resulting in console with display lights, wasted computer toggle switches, some form time of input device, and a printer Setup time A considerable amount of Users have access to the computer in “series” time was spent on setting up the program to run Copyright © 2018 Pearson Education, Ltd. All Rights Reserved.  Simple Batch Systems Early computers were very expensive Important to maximize processor utilization Monitor User no longer has direct access to processor Job is submitted to computer operator who batches them together and places them on an input device Program branches back to the monitor when finished Copyright © 2018 Pearson Education, Ltd. All Rights Reserved.  Monitor Point of View Monitor controls the sequence of events Resident Monitor is software always in memory Monitor reads in job and gives control Job returns control to monitor Copyright © 2018 Pearson Education, Ltd. All Rights Reserved.  Processor Point of View Processor executes instruction from the memory containing the monitor Executes the instructions in the user program until it encounters an ending or error condition “Control is passed to a job” means processor is fetching and executing instructions in a user program “Control is returned to the monitor” means that the processor is fetching and executing instructions Copyright from © 2018 Pearson Education, Ltd.the monitor program All Rights Reserved.  Job Control Language (JCL) Special type of programming language used to provide instructions to the monitor What compiler to use What data to use Copyright © 2018 Pearson Education, Ltd. All Rights Reserved.  Desirable Hardware Features Memory protection While the user program is executing, it must not alter the memory area containing the monitor Timer Prevents a job from monopolizing the system Privileged instructions Can only be executed by the monitor Interrupts Gives OS more flexibility in controlling user programs Copyright © 2018 Pearson Education, Ltd. All Rights Reserved.  Modes of Operation User Mode Kernel Mode User program executes Monitor executes in in user mode kernel mode Certain areas of Privileged instructions memory are protected may be executed from user access Protected areas of Certain instructions may memory may be not be executed accessed Copyright © 2018 Pearson Education, Ltd. All Rights Reserved.  Simple Batch System Overhead Processor time alternates between execution of user programs and execution of the monitor Sacrifices: Some main memory is now given over to the monitor Some processor time is consumed by the monitor Despite overhead, the simple batch system improves utilization of the computer Copyright © 2018 Pearson Education, Ltd. All Rights Reserved.  Multiprogrammed Batch Systems I/O devices are slow compared to processor Even with automati c job sequenci ng Processor is often idle Copyright © 2018 Pearson Education, Ltd. All Rights Reserved. Copyright © 2018 Pearson Education, Ltd. All Rights Reserved.  Uniprogramming The processor spends a certain amount of time executing, until it reaches an I/O instruction; it must then wait until that I/O instruction concludes before proceeding Copyright © 2018 Pearson Education, Ltd. All Rights Reserved.  Multiprogramming There must be enough memory to hold the OS (resident monitor) and one user program When one job needs to wait for I/O, the processor can switch to the other job, which is likely not waiting for I/O Copyright © 2018 Pearson Education, Ltd. All Rights Reserved.  Multiprogramming Also known as multitasking Memory is expanded to hold three, four, or more programs and switch among all of them Copyright © 2018 Pearson Education, Ltd. All Rights Reserved.  Multiprogramming Example Table 2.1 Sample Program Execution Attributes Copyright © 2018 Pearson Education, Ltd. All Rights Reserved. Copyright © 2018 Pearson Education, Ltd. All Rights Reserved.  Time-Sharing Systems Can be used to handle multiple interactive jobs Processor time is shared among multiple users Multiple users simultaneously access the system through terminals, with the OS interleaving the execution of each user program in a short burst or quantum of computation Copyright © 2018 Pearson Education, Ltd. All Rights Reserved.  Table 2.3 Batch Multiprogramming versus Time Sharing Copyright © 2018 Pearson Education, Ltd. All Rights Reserved.  Compatible Time- Sharing System (CTSS) One of the first time-sharing operating systems Developed at MIT by a group known as Project MAC The system was first developed for the IBM 709 in 1961 Ran on a computer with 32,000 36-bit words of main memory, with the resident monitor consuming 5000 of that Utilized a technique known as time slicing System clock generated interrupts at a rate of approximately one every 0.2 seconds At each clock interrupt the OS regained control and could assign the processor to another user Thus, at regular time intervals the current user would be preempted and another user loaded in To preserve the old user program status for later resumption, the old user programs and data were written out to disk before the new user programs and data were read in Old user program code and data were restored in main memory when that program was next given a turn Copyright © 2018 Pearson Education, Ltd. All Rights Reserved. Copyright © 2018 Pearson Education, Ltd. All Rights Reserved.  Major Achievements Operating Systems are among the most complex pieces of software ever developed Major advances in development include: Processes Memory management Information protection and security Scheduling and resource management System structure Copyright © 2018 Pearson Education, Ltd. All Rights Reserved.  Process Fundamental to the structure of operating systems A process can be defined as: A program in execution An instance of a running program The entity that can be assigned to, and executed on, a processor A unit of activity characterized by a single sequential thread of execution, a current state, and an associated set of system resources Copyright © 2018 Pearson Education, Ltd. All Rights Reserved.  Components of a Process A Theexecution context process contains three is essential: It is the internal data by components: which the OS is able to supervise and control the An executable process program Includes the contents of The associated data the various process needed by the registers Includes information such program (variables, as the priority of the work space, buffers, process and whether the etc.) process is waiting for the The execution completion of a particular I/O event context Copyright (orEducation, © 2018 Pearson “process Ltd. All Rights Reserved.  Process Management  The entire state of the process at any instant is contained in its context  New features can be designed and incorporated into the OS by expanding the context to include any new information needed to support the feature Copyright © 2018 Pearson Education, Ltd. All Rights Reserved.  Causes of Errors Improper Nondeterminate synchronization program operation It is often the case that a When programs share memory, routine must be suspended awaiting an event elsewhere in and their execution is the system interleaved by the processor, Improper design of the they may interfere with each signaling mechanism can result other by overwriting common in loss or duplication memory areas in unpredictable ways The order in which programs Failed mutual exclusion are scheduled may affect the More than one user or program outcome of any particular attempts to make use of a program shared resource at the same time Deadlocks There must be some sort of It is possible for two or mutual exclusion mechanism more programs to be that permits only one routine at hung up waiting for a time to perform an update each other against Copyright the © 2018 file Education, Ltd. All Rights Pearson Reserved.  Memory Management The OS has five principal storage management responsibilities: Automatic Support of allocation Protection Process modular Long-term and and access isolation programmi storage manageme control ng nt Copyright © 2018 Pearson Education, Ltd. All Rights Reserved.  Virtual Memory A facility that allows programs to address memory from a logical point of view, without regard to the amount of main memory physically available Conceived to meet the requirement of having multiple user jobs reside in main memory concurrently Copyright © 2018 Pearson Education, Ltd. All Rights Reserved.  Paging Allows processes to be comprised of a number of fixed-size blocks, called pages Program references a word by means of a virtual address, consisting of a page number and an offset within the page Each page of a process may be located anywhere in main memory The paging system provides for a dynamic mapping between the virtual address used in the program and a real address (or physical Copyright © 2018 Pearson Education, Ltd. All Rights Reserved. Copyright © 2018 Pearson Education, Ltd. All Rights Reserved. Copyright © 2018 Pearson Education, Ltd. All Rights Reserved.  Information Protection and Security The nature of the threat that concerns Main an organization will vary greatly issu Availability modular depending on the programming es circumstances The problem involves controlling Authenticity Confidentiality access to computer systems and the Data information stored integrity in them Copyright © 2018 Pearson Education, Ltd. All Rights Reserved.  Scheduling and Resource Management Key responsibility of an OS is Efficienc Fairness managing y resources Resource Differential responsiven allocation policies ess must consider: Copyright © 2018 Pearson Education, Ltd. All Rights Reserved. Copyright © 2018 Pearson Education, Ltd. All Rights Reserved.  Different Architectural Approaches Demands on operating systems require new ways of organizing the OS Different approaches and design elements have been tried: Microkernel architecture Multithreading Symmetric multiprocessing Distributed operating systems Object-oriented design Copyright © 2018 Pearson Education, Ltd. All Rights Reserved.  Microkernel Architecture Assigns only a few essential functions to the kernel: Address Interprocess space Basic communicatio manageme scheduling n (IPC) nt The approach: Simplifies Well suited to Provides implementatio a distributed flexibility n environment Copyright © 2018 Pearson Education, Ltd. All Rights Reserved.  Multithreading Threa Proce Technique in d ss which a process, Dispatchable unit of work A collection of one or more threads and executing an Program counter, stack pointer associated system resources application, is divided into By breaking a single application into multiple threads, a threads that Includes a processor context and its own programmer has greater control over the can run data area for a stack modularity of the application and the concurrently timing of application- related events Executes sequentially and is interruptible Copyright © 2018 Pearson Education, Ltd. All Rights Reserved.  Symmetric Multiprocessing (SMP) Term that refers to a computer hardware architecture and also to the OS behavior that exploits that architecture The OS of an SMP schedules processes or threads across all of the processors The OS must provide tools and functions to exploit the parallelism in an SMP system Multithreading and SMP are often discussed together, but the two are independent facilities An attractive feature of an SMP is that the existence of©multiple Copyright processors 2018 Pearson Education, is transparent to the user Ltd. All Rights Reserved.  SMP Advantages More than one process can be Performa running simultaneously, each nce on a different processor Availabilit Failure of a single process y does not halt the system Incremen Performance of a system tal can be enhanced by adding Growth an additional processor Vendors can offer a range of products based on the number Scaling of processors configured in the system Copyright © 2018 Pearson Education, Ltd. All Rights Reserved. Copyright © 2018 Pearson Education, Ltd. All Rights Reserved.  OS Design Distributed Object-Oriented Operating System Design Lends discipline to the Provides the illusion of a single main memory space process of adding modular extensions to a small kernel and a single secondary memory space plus other Enables programmers to unified access facilities, such customize an operating as a distributed file system system without disrupting system integrity State of the art for distributed operating Also eases the development systems lags that of of distributed tools and full- uniprocessor and SMP blown distributed operating operating systems systems Copyright © 2018 Pearson Education, Ltd. All Rights Reserved.  Questions 1) An __________ is a program that controls the execution of application programs and acts as an interface between applications and the computer hardware. 2) The portion of the monitor that is always in main memory and available for execution is referred to as the _________. 3) __________ is a technique in which a process, executing an application, is divided into threads that can run concurrently. 4) Two major problems with early serial processing systems were scheduling and __________. 5) The central idea behind the simple batch-processing scheme is the use of a piece of software known as the _________. 6) Any resource allocation and scheduling policy must consider three factors: Fairness, Differential responsiveness, and __________. 7) A __________ is set at the beginning of each job to prevent any single job from monopolizing the system. 8) The OS has five principal storage management responsibilities: process isolation, automatic allocation and management, support of modular programming, protection and access control, and __________. Copyright © 2018 Pearson Education, Ltd. All Rights Reserved.  Questions 9) The earliest computers employed __________ processing, a name derived by the way the users have access to the systems. 10) __________ was designed to keep the processor and I/O devices, including storage devices, simultaneously busy to achieve maximum efficiency. 11) In a time-sharing, multiprogramming system, multiple users simultaneously access the system through __________. 12) The principal objective of __________ is to maximize processor use. 13) Three major lines of computer system development created problems in timing and synchronization that contributed to the development of the concept of the process: multiprogramming batch operation, time sharing, and __________. 14) ___________ is a facility that allows programs to address memory from a logical point of view, without regard to the amount of main memory physically available. 15) Security and protection as it relates to operating systems is grouped into four categories: Availability, Data integrity, Authenticity, and __________. Copyright © 2018 Pearson Education, Ltd. All Rights Reserved.  Questions 16) The technique where a system clock generates interrupts, and at each clock interrupt the OS regains control and assigns the processor to another user, is __________. A) time slicing B) multithreading C) round robin D) clock cycle 16 17) is where the OS must prevent independent processes from interfering with each other's memory, both data and instructions. A) Support of modular programming B) Process isolation C) Automatic allocation and management D) Protection and access control 18) A special type of programming language used to provide instructions to the monitor is __________. A) FPL B) JCL C) DML D) SML Copyright © 2018 Pearson Education, Ltd. All Rights Reserved.