SMD149 - Operating Systems · Operating Systems Hardware and Software Concepts Summary SMD149 ... Operating Systems by H. M. Deitel, ... More advanced services …

IntroductionOperating Systems

Hardware and Software ConceptsSummary

SMD149 - Operating Systems

Roland Parviainen

October 31, 2005

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OverviewCourse Information

Roland Parviainen

E-mail: [email protected], [email protected]

Phone: 070-5317170

Office: ?Web: http://parviainen.org

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Outline

Introduction to the course

Introduction to Operating systems and a brief history

Hardware and software concepts

Summary

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Course Objectives

Fundamental course in systems programming and operating systems(theory and development)

By the end of this course, you should

Have gained an understanding of the evolution and purpose of anoperating systemBe able to describe the key elements of an operating system andtheir functionalities and interdependencesHave learnt the significance of application programming interface(API)Have gained hands-on experience in implementing some OSfunctionalities

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Course Information

Prerequisites

SMD135 Program and data structures

SMD137 Computer organization and logic design

SMD138 Real-time systems

Course textbook

Operating Systems by H. M. Deitel, P. J. Deitel and D. R. Choffnes,Prentice Hall Publication, 3rd edition, 2004 (ISBN: 0131246968)

Available at Bokis (680 kr)

Other modern Operating Systems books should work as well

http://www.sm.luth.se/csee/courses/smd/149/

Home work assignments, labs, news, slides, etc.

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Course Structure

Modules

Theoretical

IntroductionProcesses and ThreadsPhysical and Virtual MemorySecondary Storage and File SystemsProcessors: Performance and ManagementNetworking and Distributed ComputingSecurity Issues

Laborations

Systems programming (C/Unix) and Operating systemsprogramming (Java/Nachos)

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Lectures and labs

15 scheduled, but only 14 will be used

2 lectures will cover laborations (systems programming, nachos)

10 scheduled labos

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Examination and grading

No final exam

Continuous examinationFive homework assignments (each worth 40 points)

You will generally have one week per homeworkLate submissions will NOT be gradedRedo or repair of assignments is not permitted; exception: if youneed 10 points or less to pass the course

Three lab assignments (each worth 100 points)

You will will generally have two weeks per labLate submission can only get a maximum of “pass grade”Submissions after LP-2 (2005/06) ends will NOT be graded

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Examination and grading

Maximum achievable number of points in the course is 500 (200theoretical + 300 laborations)

To pass the course (i.e., grade ’3’), you need to have passed boththe theoretical and practical parts of the course

At least 100 points to pass the theory partAt least 150 points to pass the laborations part

Grade ’4’ - at least 325 points and passed both parts

Grade ’5’ - at least 400 points and passed both parts

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IntroductionHistoryArchitectures

Operating systems

What is an operating system

“The software that controls the hardware”

“...all the software that is required in order for the user to managethe system and to run third-party application software for thatsystem.”

“In computing, an operating system (OS) is the system softwareresponsible for the direct control and management of hardware andbasic system operations. Additionally, it provides a foundation uponwhich to run application software such as word processing programsand web browsers.”

Resource manager

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Operating systems

Components

Kernel

Shell

Core components

Often in the kernel:

Processor scheduler

Memory manager

I/O manager

Interprocess communication (IPC) manager

File system manager

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Operating systems

What is part of an operating system

Kernel, Shells, Software Libraries, Application Programs, GUIs?

Controversy

United States v. Microsoft antitrust trials

GNU/Linux naming controversy

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Brief history

40s and 50s

Early computers had no operating system

Single job at a time

Faster computers - job switching overhead increased

Single stream batch-processing systems

Programs and data submitted at the same time

Machine operators, not users, handled computers

Replaced by operating systems...

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60s

Several jobs at a time

I/O bound and processour bound jobs

Multiprogramming

1964: System/360 with OS/360 from IBM (later MFT, MVT, SVS,MVS, MVS/XA, MVS/ESA, OS/390 and z/OS)

Interactive users

Timesharing

Real-time systems

response in bounded time periods

CTSS (Compatible time-sharing system), TSS (Time-sharingsystem), Multics, CP/CMS (Control program/ConversationalMonitor System)

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60s

Multics

Developed using CTSSHigh level languageHardware: 400-1000 KMIPSPartly inspired Unix (Unics - Multics - bad pun...)

Virtual Memory

Unix

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70s

Commercialization of time-sharing systems

Ethernet/LANs

Foundations of Internet are started

TCP, TCP/IP

Personal computing starts

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80s

TCP/IP replaces NCP, DNS is developed

8 and 16 bit personal computers

GUIs

Xeroc Palo Alto Research Center (Xerox PARC)Apple Macintosh

Distributed computing - client/server

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90s

HTTP and WWW

Distributed computing explosion

PCs with hundreds of MIPS

Microsoft domination

Plug and play

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00s

Middleware

Web services

Small and mobile devices

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Architectures

Components

Kernel

Shell

Core components

Processor scheduler

Memory manager

I/O manager

Interprocess communication (IPC) manager

File system manager

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Monolithic

All core components inside the kernel

Modules can communicate directly through function calls

Highly efficient

Bugs and errors can be hard to isolate

Security?

Linux, many BSD systems, Solaris

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Layered

Groups similar functions in layers

Layers communicate only with the layer above or below

Interfaces hides implementation

Calls may have to go through several layers

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Microkernel

Kernel only provides a small number of services (MM, IPC,synchronization)

More advanced services are implemented as user processes

Often inefficient: intermodule communication, context switches areexpensive, etc.

Mach, L4, QNX, BeOS, Minix

Not to be confused with modular monolithic operating systems

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Microkernel vs. Monolithic vs. Layered

Famous discussion: Linus Torvalds vs. Andy Tanenbaum, 1992:“Linux is obsolete”(http://www.oreilly.com/catalog/opensources/book/appa.html)

Often partly mixed

MacOS X, Windows NT (and XP, Vista, etc)

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Network and distributed systems

Network Operating systems

Runs on one computer

Allows its processes to access resources on remote computers

Distributed operating systems

Single OS that manages resources on more than one computersystem

Amoeba, Chord

Goals

Transparent performanceScalabilityFault toleranceConsistency

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Hardware components

A computer’s hardware typically consists of:

processor(s)main memoryinput/output devices

Printed Circuit Board (PCB)

Hardware component that provides electrical connections betweendevices

The mainboard is the central PCB in a computer

Devices such as processors and main memory are attachedInclude chips to perform low-level operations (e.g., BIOS)

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Processor

A processor is hardware that executes machine- language

CPU executes the instructions of a program

Coprocessor executes special-purpose instructions

Registers are high-speed memory located on processorsData must be in registers before a processor can operate on itInstruction length is the size of a machine-language instruction

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Main memory and storage

Memory

Main memory consists of volatile random access memory (RAM)

Processes can access data locations in any orderCommon forms of RAM include:

dynamic RAM (DRAM) - requires refresh circuitstatic RAM (SRAM) - does not require refresh circuit

Secondary storage

Secondary storage stores large quantities of persistent data at lowcost

Accessing data on a hard disk is slower than main memory

Mechanical movement of read/write headRotational latencyTransfer time

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Buses

A bus is a collection of traces

Traces are thin electrical connections that transport informationbetween hardware devices

A port is a bus that connects exactly two devices

An I/O channel is a bus shared by several devices to perform I/Ooperations

Example, the frontside bus (FSB) connects a processor to mainmemory

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Direct Memory Access (DMA)

DMA improves data transfer between memory and I/O devices

Devices and controllers transfer data to and from main memorydirectlyProcessor is free to execute software instructionsDMA channel uses an I/O controller to manage data transfer

Notifies processor when I/O operation is complete

Improves performance in systems that perform large numbers of I/Ooperations (e.g., mainframes and servers)

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Processor support for Operating Systems

Processor protection mechanismns for operating systems

Prevents processes from accessing privileged instructions or memory

Computer systems generally have several different execution modes:User mode (user state or problem state)

User may execute only a subset of instructions

Kernel mode (supervisor state)

Processor may access privileged instructions and resources on behalfof processes

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Interrupts and exceptions

Discovering changes

Polling

Interrupts

Exception

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Timers and Clocks

Timers

An interval timer periodically generates an interrupt

Operating systems use interval timers to prevent processes frommonopolizing the processor

Clocks

Provide a measure of continuity

A time-of-day clock enables an OS to determine the current timeand date

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Bootstrapping

Loading initial OS components into memoryPerformed by a computer’s Basic Input/Output System (BIOS)

Initializes system hardwareLoads instructions into main memory from a region of secondarystorage called the boot sector

If the system is not loaded, the user will be unable to access any ofthe computer’s hardware

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Caching

Caches

Relatively fast memory

Maintain copies of data that will be accessed soon

Increase program execution speed

Examples include:

L1 and L2 processor cachesMain memory can be viewed as a cache for hard disks and othersecondary storage devices

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Buffering and Spooling

Buffers

Temporary storage area that holds data during I/O transfers

Primarily used to:

Coordinate communications between devices operating at differentspeedsStore data for asynchronous processingAllow signals to be delivered asynchronously

Spooling

Buffering technique in which an intermediate device, such as a disk,is interposed between a process and a low-speed I/O device

Allows processes to request operations from a peripheral devicewithout requiring that the device be ready to service the request

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Software support

Programming languages

Some are directly understandable by computers, others requiretranslationClassified generally as either:

Machine languageAssembly languageHigh-level language

Compilers, Interpreters, Loaders

Firmware

Middleware

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Compiling, Linking and Loading

Before a high-level-language program can execute, it must be:

Translated into machine languageLinked with various other machine-language programs on which itdependsLoaded into memory

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Compiling

Translating high-level code to machine code

Accepts source code as input and returns object code

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Linking

Create a single executable unit

Integrate precompiled modules called libraries referenced by aprogram

Assign relative addresses to different program or data units

Resolve all external references between subprograms

Produce an integrated module called a load module

Linking can be performed at compile time, before loading, at loadtime or at runtime

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Dynamic linking

Executable contains undefined symbols

and a list with objects/libraries that provides definitions

Libraries need to be stored in one location only

Errors in libraries can easily be fixed

Multiple versions of libraries?

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Loading

Convert relative addresses to physical addresses

Place each instruction and data unit in main memory

Techniques for loading a program into memoryAbsolute loading

Place program at the addresses specified by programmer or compiler(assuming addresses are available)

Relocatable loading

Relocate the program’s addresses to correspond to its actual locationin memory

Dynamic loading

Load program modules upon first use

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Firmware and Middleware

Firmware contains executable instructions stored in persistentmemory attached to a device

Programmed with microprogramming

Layer of programming below a computer’s machine-languageMicrocode: simple, fundamental instruction necessary to implementall machine-language operations

More and more frequently: high-level languages

Middleware is software for distributed systems

Enables interactions among multiple processes running on one ormore computers across a networkFacilitates heterogeneous distributed systemsSimplifies application programming

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Summary

http://www.sm.luth.se/csee/courses/smd/149/

Home work assignment 1 deadline: 14 Nov.

Next: Processes and threads

Chapters 3, 4, 5 (Sections 5.1- 5.3), 8 (Sections 8.1- 8.7.5)

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SMD149 - Operating Systems · Operating Systems Hardware and Software Concepts Summary SMD149 ... Operating Systems by H. M. Deitel, ... More advanced services …