operating system introduction and types with function
- 2. 2 Outlin e • What is an Operating System? • Operating System Functions • Operating System features • Operating System variants
- 3. 3 Operating System • A modern computer system consists of: – one or more processors, – main memory, disks, printers, – a keyboard, a display, – network interfaces, and – other input output devices, – All in all, a complex system. • In order to: – Manage all these devices for granting proper function and interaction with each other, – To create user friendly environment, and – User programs with a simpler interface to the hardware, • there is a program known as Operating system.
- 4. 4 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: – Manage computer system resources. – Make the computer system convenient to use. • Use the computer hardware in an efficient manner. • To manage and share/multiplex resources in time and space (resource manager). – Time multiplexing – E.g. sharing CPU, printer... – Resource multiplexing – E.g. sharing main memory
- 5. 5 What is an Operating System?... An operating system is: A collection of software components that • Provides useful abstractions and • Manages resources to • Support application programs, and • Provide an interface for users and programs Resource allocator – manages and allocates resources. Control program – controls the execution of user programs and operations of I/O devices.
- 6. What does Operating System do? • Manages all the resources in a computer (including processor, memory, i/o devices) • Provides an interface between the hardware and application software. • Three layers: • Inner layer, computer hardware • Middle layer, operating system • Outer layer, different software 6
- 7. 7 Operating System Functions • An operating system’s main functions are: – Multiprogramming, multiprocessor – Computer resource management – Provides a user interface – Runs software utilities and programs – Schedule jobs – Provide tools to configure the operating system and hardware – Administers user actions and accounts – Enforce security measures
- 8. 8 Operating System Functions… An operating system’s main functions are: … • Schedule processes & multiplex CPU • Provide mechanisms for IPC and synchronization • Manage main memory • Manage other resources (E.g, Input/Output) • Provide convenient persistent storage (files) • Maintain system integrity, handle failures • Enforce security policies (e.g., access control) • Give users and processes an interface
- 10. Operating System features • Authentication of users – password, passphrase comparison, biometrics, digital authentication (SSL, CA, PKI, Kerberos, DS) • Mandatory (enforce multilevel security by classifying the data and users into various security classes) and • Discretionary Access Control (grant privileges to users) • Protection of memory – user space, paging, segmentations • File and I/O device access control – access control matrix • Enforcement of sharing resources – To preserve integrity, consistency (critical section) 10 10
- 11. 11 Operating System features… • Fair service – no starvation and deadlock • Inter-process communication & synchronization – Shared variable (e.g, using semaphores) • Protection of data – encryption, isolation – …
- 12. 12 Computer System Components 1.Hardware – provides basic computing resources (CPU, memory, I/O devices). 2.Operating system – controls and coordinates the use of the hardware among the various application programs for the various users. 3.Applications programs – define the ways in which the system resources are used to solve the computing problems of the users (compilers, database systems, video games, business programs). 4.Users (people, machines, other computers).
- 13. Abstract View of System Components 13
- 15. 15 Mainframe Systems • The Operating systems for main frames are heavily oriented towards processing of many jobs at once (many I/O devices). • Reduce setup time by batching similar jobs. • Automatic job sequencing – automatically transfers control from one job to another. • They typically offer three kinds of services: – Batch System – Transaction processing system – Time sharing system
- 16. Memory Layout for a Simple Batch System Batch system - is one that processes routine jobs in the absence of interactive user. E.g: Multiprogrammed Batch Systems Several jobs are kept in main memory at the same time, and the CPU is multiplexed among them. 16
- 17. 17 OS Features Needed for Multiprogramming • I/O routine supplied by the system. • Memory management – the system must allocate the memory to several jobs. • CPU scheduling – the system must choose among several jobs ready to run. • Allocation of resources.
- 18. 18 Transaction processing system • handles large number of small requests. • Each unit of work is small but the system must handle thousands per second. • E.g. check processing at bank, airline reservation.
- 19. 19 Time-Sharing Systems–Interactive Computing • The CPU is multiplexed among several jobs that are kept in memory and on disk (the CPU is allocated to a job only if the job is in memory). – A job swapped in and out of memory to the disk. – On-line communication between the user and the system is provided; • when the operating system finishes the execution of one command, it seeks the next “control statement” from the user’s keyboard. – On-line system must be available for users to access data and code.
- 20. 20 Desktop Operating Systems • Personal computers – computer system dedicated to a single user. – I/O devices – keyboards, mice, display screens, small printers. – User convenience and responsiveness. • Often individuals have sole use of computer and do not need advanced CPU utilization of protection features. • May run several different types of operating systems (Windows, MacOS, UNIX,…) • Linux (RedHat, OpenSuSe, Fedora, Obuntu,..)
- 21. 21 Parallel Systems (Multiprocessor OS) • Connecting multiples CPU’s into a single system. • Multiprocessor systems with more than on CPU in close communication. • Tightly coupled system – processors share bus, memory, clock and peripheral device. • communication usually takes place through the shared memory. • Advantages of parallel system: – Increased throughput – Economical - they can share mass storage, peripherals,… – Increased reliability • If one fail, the other will take responsibility
- 22. Multiprocessors OS… • Like a uniprocessor operating system • Manage multiple CPUs transparently to the user • Each processor has its own hardware cache – Maintain consistency of cached data A b u s - b 22
- 23. 23 Multiprocessor OS… • Are similar to multiprogrammed uniprocessor operating systems in many respects and – they perform resource management and – hide unpleasant features of the hardware to provide a high-level machine abstraction to the users. • Are more complex because multiple processors execute tasks concurrently – with physical concurrency as opposed to virtual concurrency in multiprogrammed uniprocessors.
- 24. Parallel Systems (Multiprocessor OS)… • Symmetric multiprocessing (SMP) – Each processor runs an identical copy of the operating system. – There is one copy of the supervisor or kernel that can be executed by all processors concurrently. – Many processes can run at once without performance deterioration. 24 Bus • Most modern operating systems support SMP • It permits the parallel execution of a single task. • Examples : Hydra OS
- 25. Parallel Systems (Multiprocessor OS)… • Asymmetric multiprocessing – Master-slave. Operating system in master processor. – Each processor except master is assigned a specific task – master processor schedules and allocated work to slave processors. – More common in extremely large systems 25 Issues • Failure of the master processor. • The master can become a bottleneck • Examples : Cyber 170 and DEC(Digital Equipment corporation) Bus
- 26. Multiprocessor OS… Separate supervisor Configuration • Each CPU has its own operating system • There is very little coupling among processors and • each processor acts as an autonomous, independent system. Bus • There are some common data structures for the interaction among processors The access to which is protected by using some synchronization mechanism (such as semaphores). 26
- 27. Uniprocessor Operating Systems Separating applications from OS code through a microkernel 27
- 28. Multicomputer (DS) Operating Systems General structure of a multicomputer operating system More complex than multiprocessor OS – Because communication has to be done through explicit message passing 28
- 29. Server Operating System • They run on servers, which are very large personal computers, workstations, or even mainframes. • They serve multiple users at once over a network. • They allow the users to share HW and SW resources. • E.g. Server can provide print service, file service, or web service. • Typical server operating systems are UNIX, Window 2003, and Linux… 29
- 30. Network Operating System • Bridges, Routers, Wireless access points 30
- 31. Network Operating System… General structure of a network operating system 31
- 32. Network Operating System… Employs a client-server model Two clients and a server in a network operating system 32
- 33. 33 Network Operating System… • Users are aware of multiplicity of machines. • Access to resources of various machines is done explicitly by • Remote logging into the appropriate remote machine. • Transferring data from remote machines to local machines, via the File Transfer Protocol (FTP) mechanism.
- 34. Distributed Operating System • Distribute the computation among several physical processors. • Loosely coupled system – each processor has its own local memory, clock, peripheral devices,… • processors communicate with one another through various communications lines, such as high-speed buses or telephone lines. • Advantages of distributed systems. – Resources Sharing – Computation speed up – load sharing – Reliability – Communications 34
- 35. Distributed Operating System… • Users not aware of multiplicity of machines. • Manages resources in a distributed system – Seamlessly and transparently to the user • Looks to the user like a centralized OS – But operates on multiple independent CPUs • Provides transparency – Location, migration, concurrency, replication,… • Presents users with a virtual uniprocessor 35
- 36. 36 Distributed Operating Systems… • Requires networking infrastructure. • Local area networks (LAN) or Wide area networks (WAN) • May be either client-server or peer-to- peer systems.
- 37. Distributed OS vs. Network OS. User is not aware of the multiple CPUs. Each machine runs a part of the Distributed Operating System. The system is fault- tolerant. User is aware of the existence of multiple CPUs. Each machine has its own private Operating System. The system is not fault- tolerant . 37
- 38. Positioning Middleware General structure of a distributed system as middleware 38
- 39. 39 Types of Operating Systems An overview of • DOS (Distributed Operating Systems) • NOS (Network Operating Systems) • Middleware System Description Main Goal DOS Tightly-coupled OS for multi-processors and homogeneous multicomputers Hide and manage hardware resources NOS Loosely-coupled OS for heterogeneous multicomputers (LAN and WAN) Offer local services to remote clients Middleware Additional layer a top of NOS implementing general-purpose services Provide distribution transparency
- 40. Middleware and Openness • In an open middleware-based distributed system, - the protocols used by each middleware layer should be the same, - the interfaces they offer to applications should also be the same 40
- 41. 41 Role of Middleware (MW) • MW tried to provide the illusion that a collection of separate machines was a single computer. • MW also supports seamless access to remote services, doesn’t try to look like a general-purpose OS • Examples of Middleware – CORBA (Common Object Request Broker Architecture) – DCOM (Distributed Component Object Management) – RPC (Remote Procedure Call) – RMI (Remote Method Invocation) – Socket (TCP,UDP)
- 42. 42 Middleware Examples… • All of the previous examples support communication across a network: • They provide: – protocols that allow a program running on one kind of computer, – using one kind of operating system, – to call a program running on another computer – with a different operating system • The communicating programs must be running the same middleware.
- 43. 43 Real-Time Operating Systems • Often used as a control device in a dedicated application such as controlling scientific experiments, industrial control systems,… • These systems are characterized by having time as a key parameter. – E.g. Governor, which is used to control the flow of water in the production of power, Industrial process controls system. • If the action absolutely must occur at a certain moment (or within a certain range), we have a hard real time OS. – E.g. Governor, flight control system, air bag in a car… • Another kind of real time system is a soft real time operating system, in which missing an occasional deadline is acceptable. – E.g. Digital audio or multimedia systems.
- 44. Embedded Operating Systems • Personal Digital Assistants (PDAs) • Cellular telephones, smart phones,… • E.g, Windows CE (Consumer Electronics) • PalmOS, Android OS,… • Issues: – Limited memory – Slow processors – Small display screens. 49
- 45. What is an embedded system? Embedded System = Computer Inside a Product. 50
- 46. Embedded systems… • Embedded computing systems – Computing systems embedded within electronic devices – Billions of units produced yearly, versus millions of desktop units – Perhaps >50 per household and per automobile – A lot more programming is done for embedded systems than desktop computers or servers Computers are in here... and here... and even here... Lots more of these, though they cost a lot less each. 51
- 47. Embedded Operating Systems… • Many different platforms: – J2ME – Android – Apple iPhone – Microsoft Windows Mobile – Blackberry – PalmWebOS – Nokia (C/C++, Python) • Symbian (S60, S80) 52
- 48. Product: Cannon EOS 3D Digital Camera 48 Microprocessor: DIGIC II Image Processor Media players are embedded systems. Microsoft’s Zune Multimedia player uses an ARM processor and the Windows CE Operating System. Product: Microsoft’s Zune Portable Media Device Microprocessor: ARM OS: Windows CE
- 49. Embedded OS… Industrial Automation • Process and plant control systems in nuclear power plants, Hydro power plants, industries. 49
- 50. Embedded OS… • Dashboard electronics such as the radio, air conditioning, and satellite navigation system, Airbags,… Efficient automatic gearboxes, media, safety … Automotive Electronics Product: S class Mercedes Microprocessors: around 100 embedded processors ! 50
- 51. Embedded OS… Aircrafts • Flight control systems, • Pilot information systems, • Power supply system, • Entertainment system, 51
- 52. Product: Samsung BlackJack II Smartphone Microprocessor: TI OMAP (ARM + DSP) OS: Windows Mobile 6 (CE) 58 Embedded OS…
- 53. WSN Operating systems TinyOS FreeRTOS RETOS C/OS II AMBIENT RT Nano- Qplus Android Windows CE Contiki 62 The “Linux” of sensor node OS Developed by ETRI Developed for mobile phone
- 54. Wireless Sensor Networks Control (actuator) and monitor (sensor) networks Initial approach Data collecting networks Wired Present approach Ad-hoc capacity Local processing Wireless Easy deployment 63
- 55. 55 Smart card operating system • The smallest operating system runs on smart card. • Contains CPU chip. • Processing power and memory constraints. • They handle a single function like electronic payment • Some of them are java oriented.