unit 1
DESCRIPTION
computer scienceTRANSCRIPT
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Operating SystemsUnit 1: OS objectives Mode of operation Components Architecture Linux Windows XPOperating Systems
COP 4994 - Operating Systems
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What Is an Operating System?Computer = set of able resourcesprocessor(s), memory, I/O & communication devicesOSenables use of resourcesmanages resourcesresources not limited to hardwareshift from: pure efficient use of resources toenhance user experience
COP 4994 - Operating Systems
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Mode of operationKernel:substance, core, center, essence, gist, heart, heart and soul, inwardness, marrow, meat, nub, pith, sum, nitty-gritty pieces of software that perform OS tasks
has privileged access to resources
COP 4994 - Operating Systems
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Terminologykernel mode or kernel space
user mode or user space
system call: user mode program invokes kernel mode functionality
COP 4994 - Operating Systems
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Operating System ComponentsProcessor schedulerMemory managerI/O managerInterprocess communication managerFile system manager
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Operating System ArchitecturesOperating systems tend to be complexProvide many services Support variety of hardware and softwareOperating system architectures help manage this complexityOrganize operating system componentsSpecify privilege with which each component executes
COP 4994 - Operating Systems
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Operating System Architecturesmonolithiclayeredmicro-kerneldistributed
COP 4994 - Operating Systems
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Monolithic ArchitectureMonolithic operating systemEvery component contained in kerneldirect communication among all elementshighly efficientProblems:complexitynew devices, emerging technologiesenabling, protection
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Monolithic Architecture
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Layered ArchitectureGroups components that perform similar functions into layersEach layer communicates only with adjacent layerSystem calls might pass through many layers before completion
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Layered Architecture
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Microkernel ArchitectureMicrokernelprovides only small number of servicesattempt to keep kernel small and scalableHigh degree of modularityExtensible, portable and scalableIncreased level of inter-module communication
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Microkernel Architecture
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Distributed Operating SystemsNetwork operating systemRuns on one computer but allows its processes to access remote resources
Distributed operating systemSingle OS manages resources on more than one computer
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Distributed Operating Systems
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Linux Kernel ArchitectureMonolithic kernel:Contains modular componentsProcess managementInterprocess communicationMemory managementFile system managementVFS: provides a single file system interfaceI/O managementNetworking
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Linux Kernel Architecture
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Loadable Kernel ModulesEnables code to be loaded on demandReduces the kernels memory footprint
Kmod: a kernel subsystem that manages modules without user interventionDetermines module dependencies and loads and unloads them on demand Problem: kernel and module versions
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Windows XP Kernel ArchitectureModified microkernel has layershas modular components within layer
MicrokernelBasic system mechanismsThread scheduling, interrupt dispatching, etc.Abstracts hardware specifics that differ between architectures
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Windows XP Kernel Architecture
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Windows XP Kernel ArchitectureExecutivemain operating system subsystems
Environment subsystemsProvide a specific computing environment for user-mode processes:Examples: Win32, SFU, WOW64
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Agenda for next week:Chapter 3: Process ConceptsChapter 4: Thread Concepts
Read ahead !
COP 4994 - Operating Systems