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Pertemuan 3Konsep Sistem Operasi

Matakuliah : T0316/sistem Operasi

Tahun : 2005

Versi/Revisi : 5

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Learning Outcomes

Pada akhir pertemuan ini, diharapkan mahasiswa

akan mampu :• menjelaskan istilah dan konsep sistem operasi

(C2)

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Outline Materi

Konsep– Processes– Deadlock– Memory

management– I/O– File– Shell– System call

Struktur

–Monolithic

–Layered

–Virtual machine

–Exokernels

–Client-Server

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 Process     Program in execution

     Consist of:

o    Executable program, data, stack

o    Program counter, stack pointer, registers

     Process table array or linked list of structure of the process in execution

     Process has:

o    Address space (core image)o   Attribute/information in the process table

          OPERATING SYSTEM CONCEPT

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     A process tree:

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     Condition in which interacting process cannot be continued and there is no process that can get out of that condition.

Deadlock

(a) A potential deadlock. (b) an actual deadlock.

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Input/Output     Independent I/O software    Device dependent, eg. device drivers

Memory Management     Multiple program dalam memory needs:

o    Protection

o    Address space management

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      Files     Directory      Pathname     Protection mode

rwx bits     File descriptor

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     Mounted file system

Before mounting After mounting

     Special fileo    Blocko    Character

      Pipe

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       Shell     Unix command interpreter

     Prompt Example:datedate > filesort < file1 > file2cat file1 file2 file3 | sort > /dev/lpcat file1 file2 file3 | sort > /dev/lp &

      Security     Protection, eg. rwx bits

     Intruders, from human or non-human (eg. virus)

    Background job

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      SYSTEM CALLS

Interface between user program and operating system

Steps in Making a System Call

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    Example of system calls: 

o    Process Management

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o    File Management

o   Directory and file system management

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o    Miscellaneous

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Monolithic system

     The big mess    No structure 

          OPERATING SYSTEM STRUCTURE

Simple structuring model

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  Generalisation of layering concept at MULTICS concentric ring

Layered System      Hierarchical layer, each layer is built on top of the layer below

it.

    Eg: THE system

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Virtual Machine      Virtual machine monitor not an extended machine, but an exact

copy of the bare hardware

    CMS (Conversational Monitor System) 

   JVM (Java Virtual Machine)

Structure of VM/370 with CMS

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Exokernels

     Designed for a system that gives each user clone of the actual computer, but with a subset of resources

    Program run on the bottom layer to allocate resources to virtual machine

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Client-server model

     Mikrokernel     Client process     Server process    Mechanism vs policy

The client-server model

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 Advantages of distributed system model:     Smaller parts are easier to maintain      No direct access toward hardware    Adaptability

The client-server model in a distributed system