operating systems sameer mahajan. overview process management interrupts memory management file...
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Operating Systems
Sameer Mahajan
Overview• Process management• Interrupts• Memory management• File system• Device drivers• Networking (TCP/IP, UDP)• Security (Process/Memory protection)• I/O
History
• 1940’s First Generation – no OS• 1950’s Second Generation – single stream
batch• 1960’s Third Generation – multiprogramming
batch• Fourth Generation – microprocessor
Types
• Realtime• Single user vs. Multi user• Multi-tasking vs. Single-tasking• Distributed• Embedded
Examples
• UNIX – 1%• Mac OS (Lion, Snow Leaopard, Leopard, X
Server) – 6%• Google chrome• AmigaOS• MS Windows (8, 7, Vista, XP, w2k8, w2k3) – 90%• Mobile Devices – iOS, Android, Windows Phone
7, Symbian
Components• Kernel• Program Execution (Process)• Interrupts• Modes• Memory Management – virtual vs physical• Multitasking – scheduling• File systems – VFS• Device drivers• Networking• Security• User interface (GUI, CLI)
Kernel
File system• Boot block• Super block• Inode Table• Data blocks• User File Descriptor (FD) table • File Table• ls, df, mount (UNIX); Explorer (windows)
File system
Process• Unit of execution• User and kernel mode• Context: stack, registers, PC• thread• Virtual memory – physical memory• ps (UNIX); Process Explorer (Windows)
Process Management
Scheduling Algorithms• FCFS Scheduling• Round Robin Scheduling• Priority Scheduling• Multilevel Queue Scheduling• Multilevel Feedback Queue Scheduling• SJF Scheduling• SRT Scheduling
IO subsystem• Open, close, read, write• Character device – ioctl• Block device – strategy• Major, minor device number• Stream – full duplex connection• Buffer cache• Memory mapped IO
Inter process communication• Messages (msg*)• Shared memory (shm*)• Semaphores (sem*)• Sockets• Pipes
Windows 8 features
• Metro User Interface• Internet Explorer 10• Apps and App Store• New Hardware and Form Factors – multitude
of devices (touch is primary interface)• Security Changes• Storage Changes (de-dupe, live disk repair)• Virtualization Changes
Hardware Virtualization