Chapter 2 Operating system overview, after studying this chapter, you should be able to: Summarize, at a top level, the key functions of an operating system (OS); discuss the evolution of operating systems for early simple batch systems to modern complex systems; discuss the key design areas that have been instrumental in the development of modern operating systems;...
Trang 1Chapter 2 Operating System Overview
Patricia Roy Manatee Community College, Venice, FL
Trang 3Operating System Objectives
• Ability to evolve
Trang 4Layers and Views
Trang 5Services Provided by the OS
Trang 6Services Provided by the OS
Trang 7Services Provided by the OS
– Internal and external hardware errors
– Software errors
– Operating system cannot grant request of application
Trang 8Services Provided by the OS
– Collect usage statistics
– Monitor performance
– Used to anticipate future enhancements
– Used for billing purposes
Trang 9Operating System
software
– It is a program that is executed
the processor
Trang 10OS as Resource Manager
Trang 11memory
Trang 15Evolution of Operating
Systems
– Monitor
• Software that controls the sequence of events
• Batch jobs together
• Program returns control to monitor when finished
Trang 16Job Control Language
– What compiler to use
– What data to use
Trang 19Memory Protection
– Certain instructions may not be executed
Trang 20Memory Protection
– Kernel mode
– Privileged instructions are executed
– Protected areas of memory may be accessed
Trang 21System Utilization Example
Trang 22complete before proceeding
Trang 23processor can switch to the other job
Trang 24Multiprogramming
Trang 25Utilization Histograms
Trang 26Example
Trang 27Time Sharing Systems
interactive jobs
users
system through terminals
Trang 28Batch Multiprogramming versus
Time Sharing
Trang 29CTSS Operation
Trang 30Major Achievements
Trang 32– A single sequential thread of execution– A current state
– An associated set of system resources
Trang 33Difficulties with Designing
System Software
Trang 35Process
Trang 36Memory Management
Trang 37Virtual Memory
files
from a logical point of view
Trang 38number of fixed-size blocks, called pages
offset within the page
main memory
main memory address
Trang 39Virtual Memory
Trang 40Virtual Memory Addressing
Trang 41Information Protection and
– Assuring that users cannot read data for
which access is unauthorized
Trang 42Information Protection and
Trang 43Scheduling and Resource
Trang 44Scheduling and Resource
Management
– Maximize throughput, minimize response time, and accommodate as many uses as possible
Trang 45Key Elements of an Operating
System
Trang 46System Structure
functions
perform more primitive functions
of more manageable subproblems
Trang 47– Processor’s instruction set
– Operations such as add, subtract, load, and store
Trang 49Concepts Related to Multiprogramming
– Process as a program in execution
– Suspend and resume processes
– Secondary storage devices
– Transfer of blocks of data
Trang 50Concepts Related to Multiprogramming
– Creates logical address space for processes– Organizes virtual address space into blocks
Trang 51Deal with External Objects
Trang 52Deal with External Objects
Trang 53Modern Operating Systems
Trang 54Modern Operating Systems
– Process is divided into threads that can run concurrently
• Thread
– Dispatchable unit of work
– executes sequentially and is interruptable
• Process is a collection of one or more threads
Trang 55Modern Operating Systems
– There are multiple processors
– These processors share same main memory and I/O facilities
– All processors can perform the same
functions
Trang 56Multiprogramming and
Multiprocessing
Trang 57Modern Operating Systems
– Provides the illusion of a single main memory space and single secondary memory space
Trang 58Modern Operating Systems
– Used for adding modular extensions to a small kernel
– Enables programmers to customize an
operating system without disrupting system integrity