CHAPTER 1: OPERATING SYSTEM FUNDAMENTALS

Size: px

Start display at page:

Download "CHAPTER 1: OPERATING SYSTEM FUNDAMENTALS"

May Price
6 years ago
Views:

1 CHAPTER 1: OPERATING SYSTEM FUNDAMENTALS What is an operating system? A collection of software modules to assist programmers in enhancing system efficiency, flexibility, and robustness An Extended Machine from the users viewpoint A Resource Manager from the system s viewpoint What are the primary functions of an operating system? multiplexing the processor(s) scheduling processes coordinating interaction among processes, interprocess communication and synchronization managing system resources (I/O, memory, data files) enforcing access control and protection maintaining system integrity and performing error recovery providing an interface to the users 1

2 Evolution of modern operating systems 1. Centralized operating system: resource management and extended machine to support Virtuality (a) Resident Monitor (RM) - user=operator, single process (b) Batch Systems - user operator, single multiple processes (c) Timesharing Systems - interactive, multiple processes (d) Personal Computers - user=operator, single multiple processes 2. Network operating system: resource sharing to achieve Interoperability 3. Distributed operating system: a single computer view of a multiplecomputer system for Transparency 4. Cooperative autonomous system: cooperative work with Autonomicity A spectrum of modern operating systems 1st Decreasing Degree of Hardware and Software Coupling 3rd 4th 2nd centralized operating system distributed operating system cooperative autonomous system network operating system Decreasing Degree of Transparency 2

3 Operating system structuring methods modularization vertical partitioning (layered one-in-one-out structure) horizontal partitioning client/server model minimal (or micro) kernel subsystem with API and SPI Example of OS Partitioning: Applications accounting word processing manufacturing Subsystems programming environment database system Utilities compiler command interpreter library System Services file system memory manager scheduler Kernel CPU multiplexing, interrupt handling, device drivers synchronization primitives, interprocess communication 3

4 API and SPI: Applications API system services SPI (or HAL) Extensible Portable Platforms Windows NT: an example of operating system structure OS / 2 client Win 32 client POSIX client OS / 2 Win 32 POSIX subsystem subsystem subsystem User Mode system service API Kernel Mode object manager security reference monitor process manager local procedure call virtual memory manager I / O manager Executives kernel with hardware abstraction hardware platform 4

5 Overview of centralized operating systems: Resource Manager Process management interprocess communication process synchronization process scheduling Memory management memory allocation and deallocation logical to physical address mapping virtual memory support: segmentation and paging protection Device management device driver buffering spooling Data management file access file sharing concurrency control data replication 5

6 Process management interprocess communication process synchronization process scheduling Process States: Starting Halting Initialize PCB Halt/ABEND Dispatch/Context switch Ready Running TRO/Context switch Unblock Block Blocked 6

7 Memory management memory allocation and deallocation logical to physical address mapping virtual memory support: segmentation and paging protection Paged Memory: Logical Address Physical Address Page Number Offset Page Frame Offset Page Table Control Bits Page Frame V D S 7

8 Device management device driver buffering spooling Device Drivers and DMA: Hardware Independent Interface Generic Driver Code Hardware Dependent Code Physical Device Interface CPU RAM System Bus DMA Device 1 Device N 8

9 Data management file access file sharing concurrency control data replication Memory Management Unit: CPU TLB MMU Cache RAM System Bus 9

10 Unix File System: Directory Disk Blocks File Name my_file.txt i node number 0x001af38 i node Table i node Owner UID Owner GID RC drwxrwxrwx Direct Blk 10 Direct Blk 0 Direct Blk 1 Direct Blk 11 Direct Blk 521 Primary IB 0 Secondary IB 1 IB 1 1 IB 2 Direct Blk 522 Direct Blk IB

11 Unix File Tables: Proc Ctl Blk Sys File Tbl i node Table PID Proc File Tbl PFT ptr rc loc mode i node # FID 11

12 Network operating system interoperability: ability of information exchange among heterogeneous systems supported by network communication protocols transport service: the primary interface between operating system and computer network characterized by common network applications (servers) remote login file transfer messaging browsing remote execution A network file system example application processes local file system file service network file system device transport management service device network drivers KERNEL service peer communication protocols application processes network file system transport service network service file service KERNEL local file system device management device drivers local hardware communication network local hardware 12

13 Distributed operating system transparency servers for supporting resource sharing and distributed processing algorithms to implement transparencies details in latter chapters Service Decomposition vs. Integration Services Decomposition in distributed systems Integration in autonomous systems 13

14 Cooperative autonomous system client/server model object model software bus (middleware, broker, or trader) CORBA and ODP Peer-to-Peer (P2P) systems Service Oriented Architecture (SOA) systems An example of cooperative autonomous system communication channels real estate agency Yellow Pages servers realtor realtor client well known server client buyer newspaper seller 14

15 Service Oriented Architecture (SOA) (from architecture) Guiding Principles Reuse, granularity, modularity, composability, componentization, interoperability Standards compliance Service identification and categorization, provisioning and delivery, monitoring and tracking SOA Elements General idea of usage is to orchestrate services to develop application. 15

16 Specific SOA Architectural Principles Service encapsulation - minimal interface Service loose coupling - minimize dependencies Service contract - documented specification and agreement Service abstraction - internals hidden Service reusability - intentional packaging of multi-use services Service composability - composite services formed from building blocks Service autonomy - owners control logic encapsulated by services offered Service optimization - clients can shop for the best service Service discoverability - meaningful descriptions available through discovery mechanisms Service relevance - granularity is right for meaningful service Why do we need distributed control algorithms? An algorithm is sometimes called protocol if it specifies coordination more than computation. algorithm changes due to message passing need for consensus algorithms due to lack of global information concurrency control algorithms to avoid interference in resource sharing coherency control algorithms to maintain consistency for data replication protocols for group communication in distributed applications fault-tolerance algorithms for handling failure and recovery real-time and distributed scheduling algorithms 16

Distributed OS and Algorithms

Distributed OS and Algorithms Fundamental concepts OS definition in general: OS is a collection of software modules to an extended machine for the users viewpoint, and it is a resource manager from the