4003-440-02 Operating Systems I Module 1. OS Structures -- Lecture Notes Prof. Alan Kaminsky -- Winter Quarter 2012 Rochester Institute of Technology -- Department of Computer Science What Is an Operating System? Examples of OSes   Views of the computer Below the operating system Above the operating system Review of Computer Organization The three major parts of a computer   Input/output I/O devices Device controllers The two methods of transferring data from/to I/O devices   Interrupts and traps   Storage hierarchy Registers Level 1 cache Level 2 cache Main memory Electronic disk Magnetic disk Optical disk Magnetic tape Review of Computer Architecture Single processor computers   Multiprocessor computers Asymmetric multiprocessors Symmetric multiprocessors (SMPs)   Multicore processors   Cluster computers   Hybrid SMP cluster computers   Distributed systems   Relationship between computer architecture and OS Single processor OS SMP/multicore OS Cluster computers/distributed systems Separate independent OSes Distributed OS   Relationship between computer architecture and application design Multiple threads, shared memory Multiple processes, message passing   The coming importance of multiprocessor programming (parallel programming) Operating System Operations Multiprogramming Why multiprogramming is good Batch/non-interactive Time sharing/interactive   Interrupt handling Interrupts from I/O devices Traps from user programs User mode and kernel (privileged) mode Timer interrupts   Process management Job scheduling CPU scheduling Threads and processes   Interprocess communication Synchronization Shared memory Messages Streams Pipes Sockets   Storage management Swapping Virtual memory File system management Mass storage management Caching of mass storage data   I/O management Peripherals Network protocol stacks   Graphical user interface (GUI) management Integrated into the OS Above the OS   Protection and security User authentication Access control Operating System Structure Three major alternatives   Monolithic OS The entire OS is one big program that runs in kernel mode Example: Early Unix systems   Modular OS OS consists of a base program that is always loaded plus modules that are loaded only when needed, all running in kernel mode Examples: Linux (2.5 million lines of code), Windows (> 5 million lines of code)   Microkernel OS OS consists of a very small program running in kernel mode (microkernel) plus lots of manager processes running in user mode Examples: Minix (microkernel has 4,000 lines of code); many embedded and real-time OSes   Pros and cons   Article: "Can we make operating systems reliable and secure?" Operating System Interfaces and APIs OS interfaces: System calls How a system call works   OS application program interfaces (APIs): Programming language subroutines What an API routine does Examples of OS APIs Portable Operating System Interface (POSIX) -- IEEE Standard 1003 (available from the IEEE Xplore Database on the RIT Wallace Library web site) Single Unix Specification (SUS) -- defines the UNIX® trademarked operating system (http://www.unix.org/) Microsoft Windows API (http://msdn.microsoft.com/en-us/library/ms123401.aspx) Android API (http://developer.android.com/reference/packages.html)   Command interpreters Text oriented shells GUI desktops Virtual Machines Virtual machines to provide virtual hardware IBM's VM VMware   Virtual machines to provide a hardware-independent computing platform Java Virtual Machine (JVM) Android Dalvik Virtual Machine Microsoft .NET Operating Systems I • 4003-440-02 • Winter Quarter 2012 Course Page Alan Kaminsky • Department of Computer Science • Rochester Institute of Technology • 4486 + 2220 = 6706 Home Page Copyright © 2012 Alan Kaminsky. All rights reserved. Last updated 20-Nov-2012. Please send comments to ark­@­cs.rit.edu.