Operating System Concepts - PDF

Chapter 1: Introduction Operating System Concepts – 10 h Edition Silberschatz, Galvin and Gagne ©2018  Chapter 1: Introduction ▪ What Operating Systems Do ▪ Computer-System Organization ▪ Computer-System Architecture ▪ Operat...

Chapter 1: Introduction Operating System Concepts – 10 h Edition Silberschatz, Galvin and Gagne ©2018  Chapter 1: Introduction ▪ What Operating Systems Do ▪ Computer-System Organization ▪ Computer-System Architecture ▪ Operating-System Operations ▪ Resource Management ▪ Security and Protection ▪ Virtualization ▪ Distributed Systems ▪ Kernel Data Structures ▪ Computing Environments ▪ Free/Libre and Open-Source Operating Systems Operating System Concepts – 10 th Edition 1.2 Silberschatz, Galvin and Gagne ©2018  Objectives ▪ Describe the general organization of a computer system and the role of interrupts ▪ Describe the components in a modern, multiprocessor computer system ▪ Illustrate the transition from user mode to kernel mode ▪ Discuss how operating systems are used in various computing environments ▪ Provide examples of free and open-source operating systems Operating System Concepts – 10 th Edition 1.3 Silberschatz, Galvin and Gagne ©2018  What Does the Term Operating System Mean? ▪ An operating system is “fill in the blanks” ▪ What about: Car Airplane Printer Washing Machine Laptop Mobile Microwave Etc. Operating System Concepts – 10 th Edition 1.4 Silberschatz, Galvin and Gagne ©2018  What is an Operating System? ▪ A program that acts as an intermediary between a user of a computer and the computer hardware ▪ Operating system goals: Execute user programs and make solving user problems (instructions) easier Make the computer system convenient to use Use the computer hardware in an efficient manner Operating System Concepts – 10 th Edition 1.5 Silberschatz, Galvin and Gagne ©2018  Computer System Structure ▪ Computer system can be divided into four components: Hardware – provides basic computing resources  CPU, memory, I/O devices Operating system  Controls and coordinates use of hardware among various applications and users Application programs – define the ways in which the system resources are used to solve the computing problems of the users  Word processors, compilers, web browsers, database systems, video games Users  People, machines, other computers Operating System Concepts – 10 th Edition 1.6 Silberschatz, Galvin and Gagne ©2018  Abstract View of Components of Computer Operating System Concepts – 10 th Edition 1.7 Silberschatz, Galvin and Gagne ©2018  What Operating Systems Do ▪ Depends on the point of view ▪ Users want ease of use and good performance Don’t care about resource utilization ▪ But shared computer such as mainframe must keep all users happy Operating system is a resource allocator and control program making efficient use of HW and managing execution of user programs ▪ Mobile devices like smartphones and tablets are resource poor, optimized for usability and battery life Mobile user interfaces such as touch screens, voice recognition ▪ Some computers have little or no user interface, such as embedded computers in devices Run primarily without user intervention Operating System Concepts – 10 th Edition 1.8 Silberschatz, Galvin and Gagne ©2018  Operating System Definition ▪ No universally accepted definition ▪ “The one program running at all times on the computer” is the kernel, part of the operating system ▪ Everything else is either A system program (ships with the operating system, but not part of the kernel) , or An application program, all programs not associated with the operating system ▪ Today’s OS also include middleware – a set of software frameworks that provide additional services to application developers such as databases, multimedia Operating System Concepts – 10 th Edition 1.9 Silberschatz, Galvin and Gagne ©2018  Overview of Computer System Structure Operating System Concepts – 10 th Edition 1.10 Silberschatz, Galvin and Gagne ©2018  Computer System Organization ▪ Computer-system operation One or more CPUs, device controllers connect through common bus providing access to shared memory Concurrent execution of CPUs Devices competing for memory cycles Operating System Concepts – 10 th Edition 1.11 Silberschatz, Galvin and Gagne ©2018  Computer-System Operation ▪ Each device controller is in charge of a particular device type ▪ Each device controller has a local buffer ▪ Each device controller type has an operating system device driver to manage it ▪ CPU moves data from/to main memory to/from local buffers ▪ I/O is from the device to local buffer of controller ▪ Device controller informs CPU that it has finished its operation by causing an interrupt Operating System Concepts – 10 th Edition 1.12 Silberschatz, Galvin and Gagne ©2018  Common Functions of Interrupts ▪ Interrupt transfers control to the interrupt service routine generally, through the interrupt vector ▪ Interrupt architecture must save the address of the interrupted instruction ▪ A trap or exception is a software-generated interrupt caused either by an error or a user request ▪ An operating system is interrupt driven Operating System Concepts – 10 th Edition 1.13 Silberschatz, Galvin and Gagne ©2018  Interrupt Timeline Operating System Concepts – 10 th Edition 1.14 Silberschatz, Galvin and Gagne ©2018  Interrupt Handling ▪ The operating system preserves the state of the CPU by storing the registers and the program counter ▪ Determines which type of interrupt has occurred: ▪ Separate segments of code determine what action should be taken for each type of interrupt Operating System Concepts – 10 th Edition 1.15 Silberschatz, Galvin and Gagne ©2018  Interrupt-drive I/O Cycle Operating System Concepts – 10 th Edition 1.16 Silberschatz, Galvin and Gagne ©2018  Computer Startup ▪ Bootstrap program is loaded at power-up or reboot Typically stored in ROM or EPROM, generally known as firmware Initializes all aspects of system Loads operating system kernel and starts execution Operating System Concepts – 10 th Edition 1.17 Silberschatz, Galvin and Gagne ©2018  Storage Structure Operating System Concepts – 10 th Edition 1.18 Silberschatz, Galvin and Gagne ©2018  Storage Structure ▪ Main memory – only large storage media that the CPU can access directly Random access Volatile Random-access memory in the form of Dynamic Random-access Memory (DRAM) ▪ Secondary storage – extension of main memory that provides large nonvolatile storage capacity Hard Disk Drives (HDD)  Disk surface is logically divided into tracks, which are subdivided into sectors Non-Volatile Memory (NVM) devices– faster than hard disks, nonvolatile Operating System Concepts – 10 th Edition 1.19 Silberschatz, Galvin and Gagne ©2018  Storage-Device Hierarchy Operating System Concepts – 10 th Edition 1.20 Silberschatz, Galvin and Gagne ©2018  Storage Hierarchy ▪ Storage systems organized in hierarchy Speed Cost Volatility ▪ Caching – copying information into faster storage system; main memory can be viewed as a cache for secondary storage ▪ Device Driver for each device controller to manage I/O Operating System Concepts – 10 th Edition 1.21 Silberschatz, Galvin and Gagne ©2018  Storage Definitions and Notation Review The basic unit of computer storage is the bit. A bit can contain one of two values, 0 and 1. All other storage in a computer is based on collections of bits. Given enough bits, it is amazing how many things a computer can represent: numbers, letters, images, movies, sounds, documents, and programs, to name a few. A byte is 8 bits, and on most computers it is the smallest convenient chunk of storage. For example, most computers don’t have an instruction to move a bit but do have one to move a byte. A less common term is word, which is a given computer architecture’s native unit of data. A word is made up of one or more bytes. For example, a computer that has 64-bit registers and 64-bit memory addressing typically has 64-bit (8-byte) words. A computer executes many operations in its native word size rather than a byte at a time. Computer storage, along with most computer throughput, is generally measured and manipulated in bytes and collections of bytes. A kilobyte, or KB , is 1,024 bytes; a megabyte, or MB, is 1,0242 bytes; a gigabyte, or GB, is 1,0243 bytes; a terabyte, or TB, is 1,0244 bytes; and a petabyte, or PB, is 1,0245 bytes. Computer manufacturers often round off these numbers and say that a megabyte is 1 million bytes and a gigabyte is 1 billion bytes. Networking measurements are an exception to this general rule; they are given in bits (because networks move data a bit at a time). Operating System Concepts – 10 th Edition 1.22 Silberschatz, Galvin and Gagne ©2018  How a Modern Computer Works A von Neumann architecture Operating System Concepts – 10 th Edition 1.23 Silberschatz, Galvin and Gagne ©2018  Direct Memory Access Structure ▪ Used for high-speed I/O devices able to transmit information at close to memory speeds ▪ Device controller transfers blocks of data from buffer storage directly to main memory without CPU intervention ▪ Only one interrupt is generated per block, rather than the one interrupt per byte Operating System Concepts – 10 th Edition 1.24 Silberschatz, Galvin and Gagne ©2018  THANK YOU Operating System Concepts – 10 th Edition 1.25 Silberschatz, Galvin and Gagne ©2018