Operating Systems Overview

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Lecture 2

• Operating Systems Overview

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?? ??

• ????? ??
• ????? ?? ??
• 1) ?? ?? ???
• 2) ?? ???? ???
• 3) ?? ???? ???? ???
• 4) ??? ???
• ?? ????? ??
• ??? ??
• ????? ??

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Operating System

• ?? ????? ??? ???? ????
• OS? ???? ??? ??? ?? ????? ??? ??? ????
• OS? ??? ?? ???? ??? ???? ?? ??? ????
• ???? ???? ??? ?????
• ?? ????? ???? ??? ?? ????? ??? ?? ??? ???
  (Masking)
• ? ????? ???, ??? ?? ?
• OS? ????? ???? ??? ????? ??

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• ??? ???? ??? ??

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OS Services(1)

• ???? ?? ?? ??
• editors, compilers, linkers, and debuggers
• ???? ??
• loading in memory, I/O and file initialization
• I/O ? ??? ?? ??
• ?? ??? ?? ??? ? ?? ???
• ??? ??
• ??? ?? ? ???? ?? ?? ??
• ??? ?? ?? ?? ??

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OS Services(2)

• ?? ??
• ?? ? ?? ???? ??
• memory error
• device failure
• ????? ??
• arithmetic overflow
• access forbidden memory locations
• ???? ??

• ?? ??
• ??? ?? ???
• ?????? ???
• ?? ???? ??

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OS Services(3)

• ?? ??
• ??? ?? ??? ?? ?? ??
• ??? ?? ???? (eg response time)
• ??? ?? ?? ??
• ?? ?? ?? (on multiuser systems)

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????? ??

• OS? ????? ???? ? ??? ??? ????? ??? ????? ??
• Character vs graphic terminals
• paging hardware ?
• OS? ??? ???? ????? ??
• ? internet support ?
• OS? ?? ? ?? ??? ?? ??? ???
• modular construction with clean interfaces
• object oriented methodology

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????? ?? ??

• ?? ?? ???(Serial Processing)
• ?? ???? ???(Simple Batch Processing)
• ?? ???? ?? ?? ??? (Multiprogrammed Batch
  Processing)
• ??? ???(Time-Sharing Systems)
• Modern Operating Systems
• ?? ???(Parallel Systems) SMP
• ?? ???(Distributed Systems)
• ??? ???(Real-Time Systems)
• ??? ???(Embedded Systems)

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?? ?? ???(Serial Processing)

• ?? ??? ??? ??? ??
• (late 1940smid 1950s)
• ?????? ?? ??? ????? ??
• ????? ??
• ?? ???
• Scheduling ????? job scheduling
• Setup time ??? job? ???? ?? setup time? ??? ??

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?? ?? ?? ??? (1)

• ??? ?? ?? (mid-1950s)
• ?? ??
• ???? ?? ??? ??? ??(job)? ??? ???? ????
• ??? ???? ??? ??? ??? ?? ????(batch)? ???? ????
• ???(Monitor) ????? ????? ? ??? ???? ????
• ?? ???(Resident monitor)? ?? ???? ?? ?????? ????
• ??? ????? ??? ?? ?????? ????(loading)

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?? ?? ?? ??? (2)

• Early batch system
• bring cards to 1401
• read cards to tape
• put tape on 7094 which does computing
• put tape on 1401 which prints output

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(No Transcript)
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???(Monitor)

• ???? ????(?????)?? ? ??(??? ????)? ??? ?? ??
  ?????? ????(loading)
• ??? ???? ?? ??? ???? ??? ????
• ??? ????? ?? ?? ?? ????
• end-of-program ???
• ?? ??
• ??? ??? ????? ???? ?? ???? ????.

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Job Control Language (JCL) (1)

• ????? ?? ??? ??? ??? ?? ?? ??
• what compiler to use
• what data to use
• ?? ??? ? -----------------gtgt
• FTN ? ????? ?? ?? ???? ??? ?? ??? ??
• LOAD? ??? ?? ??? ?????? ???(loading)
• RUN ? ??? ????? ????

JOB FTN ... FORTRAN program ... LOAD RUN ...
Data ... END
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Job Control Language (JCL) (2)

• Structure of a typical FMS job 2nd generation

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?? ?? ????

• CPU ? ?? ??? ??? ????? ??
• ??? ????? ???? ???? ??? CPU? ??? ??? ??? ??? idle
  ??? ???
• ??? ????? ??? ????? ??? ????
• ????? ?? ?? ????? ???? ?? ???? ???? ???? ??? ???
  ??

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???? ?? ??(1)

• ??? ??
• ??? ????? ??? ??? ???? ??? ? ??? ??? ?? ?? ??
• ???
• ??? ??? ???? ???? ?? ???
• ??? ??? ??? ????? ????

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???? ?? ??(2)

• ?? ???
• ??? CPU ??? ?? ??
• ??? ??
• ??? ??(?? ?????(Supervisor) ??)
• ???? ???? ???? ???
• ??? ????? ???? ???? ??
• ????
• ??? ????? ??? ??? ??? ??? ????? ? ? ??? ??

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?? ???? ???? ???(1)

• I/O ??? ????? ?? ???? ??? ??? ???
• I/O ???? ?? ????? ???? ??? ???? ????? ????
• ??? ?????? ??? ????? ?? ??(uniprogramming)?? CPU?
  ???? ????

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?? ???? ???? ???(2)

• ?? ?????? ?? ?? ????? ?? ??, ??? ????? ??? ???
  ???? ?? CPU ? ?? ????? ??? ? ??.
• multitasking (multiprogramming)

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?? ???? ???? ???(3)
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?? ? ?? ????? ?? (1)

• ??

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?? ? ?? ????? ?? (2)
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?? ? ?? ????? ?? (3)
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?? ????? ?? ??

• Hardware support
• I/O interrupts and (possibly) DMA
• Memory management
• Memory protection (data and programs)
• Software support from the OS
• Scheduling (which program is to be run next)
• To manage resource contention

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??? ???(Time Sharing Systems)(1)

• ?? ???? ???? ???? ???? ??? ??? ???? ???
• ? ?? ?? ??(Job Turnaround Time)
• ???? ?? ??? ??? ??? ????? ?? 2? ???? ?? ??????
  ????
• ??? ??? ?? 30?? ???? ???? ??? ? ??

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??? ???(Time Sharing Systems)(2)

• ??? ???? ??? ??? ??? ???? ??? ?? ????? ??? ???
  ?????
• ??? ????? ???? ??? ????? ??
• Time Slice ??? ??? ????? ???? ??
• ?? ?? ??(Respone Time)
• ??? ???? ????? ??? ???? ??? ? ??(??? ?? ??)
• ?? ??? ?? ????? ??

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??? ???(Time Sharing Systems)(3)
?
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Batch Multiprogramming vs. Time Sharing
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Early Example CTSS

• Compatible Time-Sharing System (CTSS)
• Developed at MIT as project MAC
• Time Slicing
• When control was passed to a user
• User program and data loaded
• Clock generates interrupts about every 0.2 sec
• At each interrupt OS gained control and could
  assign processor to another user

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CTSS Operation
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Problems and Issues

• ??? ??
• Multiple jobs in memory must be protected from
  each others data
• ????? ??
• File system must be protected so that only
  authorised users can access
• ?? ?? ??
• Contention for resources must be handled
• Printers, storage etc

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Modern Operating Systems? ??(1)

• ??? ????? ??? ????? ?? ?? ??
• ??? ????? ??
• multiprocessor machines
• high-speed networks
• faster processors and larger memory
• ??? ????? ???
• multimedia applications
• Internet and Web access
• Client/Server applications

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Modern Operating Systems? ??(2)

• Microkernel Architecture
• Multithreading
• Symmetric Multiprocessing
• Distributed Systems
• Embedded Systems
• Object-Oriented Design

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Microkernel architecture

• ???? ?? ???? ???? ??
• primitive memory management (address space)
• Interprocess communication (IPC)
• basic scheduling
• ?? OS ???? ??? ?? ????(servers) ?? ??
• device drivers, file system, virtual memory
• More flexibility, extensibility, portability
• ?? ????? microkernel ??? ???? ?? ??(? Window-NT
  ?)

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Multithreading

• ??? ????? ??? ?? ??? thread ?? ????
• ????? ??? ??? ?? task? ????? ?? ????? ?? ????
• ?? ???? ??? ???? ?
• ??? ????? ???? thread? ??? ???? ??? ????

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Symmetric Multiprocessing (SMP)

• ??? ????? ?? ???
• ? ????? ??? ??? ??? ?????? I/O ???
  ????(symmetric)
• ????? ????/???? ?????? ??????(real parallelism)
• Incremental growth
• just add another CPU!
• Robustness
• a single CPU failure does not halt the system,
  only the performance is reduced

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Example of parallel execution on SMP
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Distributed Systems

• ??? ????? ?? ???? ?? ???? ?? ?? ??? ??? ???
• Loosely-coupled multiprocessor systems
• Clustered Systems
• ?? ????? ??
• ?? ?? ??????? ?
• ???? ?? ????(load balancing) ?
• ???(reliability) HA(High Availability) ?

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Embedded Systems

• ??, ?? ?? ?? ??? ?? ?? ??? ???? ?? ??? ???
• PDA, ?????, ???? ?? ??? ???? ??? ???? ???
• ??? ??? ??
• ??, ??? ? ?? ??? ?? ??? ??
• ???? ???? ??
• RTOS(Real-time Operating System)- pSos etc
• Window-CE, Embedded Window-XP
• Embedded Linux

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Object-Oriented Design

• ?? ??? ???? ???? ?? ??
• ?? ?? ?? ??? ?? ??? ?? ?? ??? ????? ??? ? ??? ??
• ?????? ???? ???? ??? ???? ??? ??? ?? ????? ??? ?
  ??
• ?? ?? ? ??? ??? ??????? ??? ???? ??

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??? ?? (1)

• ??? ??(System Calls)
• ??? ????? ???? ?? ?????
• ?? ????? ??? ?? ??
• ????? ????? ?? ??
• ??? ?? ?? ? ?? ?? ????
• ?? ?? ?? ? ?? ?? ??? ?? ???
• ?? ?? ?? / ?? ?? ??
• ?? ?? / ?? ??
• ?? ??
• ??? ??
• ???? ??

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??? ?? (2)
??? ????
??? ??
????
????? ??
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??? ?? ?? ??

• There are 11 steps in making the system call read
  (fd, buffer, nbytes)

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??? ?? ?? (1)

• ???? ??(Process Control)
• ???? ?? ? ??
• ???? ?? ? ??
• ???? ?? ?? ? ?? ?

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??? ?? ?? (2)

• A stripped simple shell
• while (TRUE) / repeat forever /
• type_prompt( ) / display prompt /
• read_command (command, parameters) / input
  from terminal /
• if (fork() ! 0) / fork off child
  process /
• / Parent code /
• waitpid( -1, status, 0) / wait for
  child to exit /
• else
• / Child code /
• execve (command, parameters, 0) /
  execute command /

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??? ?? ?? (3)

• ?? ??(File Management)
• ?? ?? ? ??
• ?? ?? ? ??
• ?? ?? ? ??
• ?? ?? ?? ? ??

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??? ?? ?? (4)

• ???? ??(Directory Management)
• ???? ?? ? ??
• ???? ??
• ????? Mounting

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??? ?? ?? (5)

• ?? ??? ??
• ?? ??(Device Management)
• ?? ?? ? ??
• ??, ??, ???
• ?? ?? ?? ? ??
• ?? ?? ??(Information Maintenance)
• ??, ?? ?? ??
• ??? ?? ?? ?
• ??(Communication)
• ?? ?? ?? ? ??
• ?? ??? ?

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??? ?? ?? (6)
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??? ?? ?? (7)

• Some Win32 API calls

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???? ??(1)

• ??? ????
• ??? ??? ????
• ???? ??? ?? ?? ??
• ??? ?? ?? ??
• ?? ?? ?? ??
• ??? ??? ?? ??? ????? ??
• ? ????, ??? ???, ???, ??? ?

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???? ??(2)
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UNIX OS ??
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Modern UNIX Kernel
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Modern UNIX Systems

• System V Release 4 (SVR4)
• Solaris 9
• 4.4BSD
• Linux

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Windows Architecture

• Modular structure for flexibility
• Executes on a variety of hardware platforms
• Supports application written for other operating
  system

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(No Transcript)
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Operating System Organization

• Modified microkernel architecture
• Not a pure microkernel
• Many system functions outside of the microkernel
  run in kernel mode
• Any module can be removed, upgraded, or replaced
  without rewriting the entire system

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Kernel-Mode Components

• Executive
• Contains base operating system services
• Memory management
• Process and thread management
• Security
• I/O
• Interprocess communication
• Kernel
• Consists of the most used components

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Kernel-Mode Components

• Hardware abstraction layer (HAL)
• Isolates the operating system from
  platform-specific hardware differences
• Device drivers
• Translate user I/O function calls into specific
  hardware device I/O requests
• Windowing and graphics systems
• Implements the graphical user interface (GUI)

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Windows Executive

• I/O manager
• Cache manager
• Object manager
• Plug and play manager
• Power manager
• Security reference monitor
• Virtual memory manager
• Process/thread manager
• Configuration manager
• Local procedure call (LPC) facility

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User-Mode Processes

• Special system support processes
• Ex logon process and the session manager
• Service processes
• Environment subsystems
• User applications

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Client/Server Model

• Simplifies the Executive
• Possible to construct a variety of APIs
• Improves reliability
• Each service runs on a separate process with its
  own partition of memory
• Clients cannot not directly access hardware
• Provides a uniform means for applications to
  communicate via LPC
• Provides base for distributed computing

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Threads and SMP

• Operating system routines can run on any
  available processor
• Different routines can execute simultaneously on
  different processors
• Multiple threads of execution within a single
  process may execute on different processors
  simultaneously
• Server processes may use multiple threads
• Share data and resources between process

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Windows Objects

• Encapsulation
• Object consists of one or more data items and one
  or more procedures
• Object class or instance
• Create specified instances of an object
• Inheritance
• Support to some extent in the Executive
• Polymorphism