Download What is an Operating System? ¯ Three views of an operating system

Intro
1
What is an Operating System?
¯ Three views of an operating system
Application View: what services does it provide?
System View: what problems does it solve?
Implementation View: how is it built?
An operating system is part cop, part facilitator.
CS350
Operating Systems
Fall 2005
Intro
2
Application View of an Operating System
¯ The OS provides an execution environment for running programs.
– The execution environment provides a program with the processor time
and memory space that it needs to run.
– The execution environment provides interfaces through which a program
can use networks, storage, I/O devices, and other system hardware
components.
£ Interfaces provide a simplified, abstract view of hardware to application
programs.
– The execution environment isolates running programs from one another
and prevents undesirable interactions among them.
CS350
Operating Systems
Fall 2005
Intro
31
Other
What
Views
is anofOperating
an Operating
System?
System
System View: The OS manages the hardware resources of a computer system.
¯ Resources include processors, memory, disks and other storage devices,
network
I/O devices
¯ Three
viewsinterfaces,
of an operating
systemsuch as keyboards, mice and monitors, and
so on. View: what services does it provide?
Application
¯ The operating
system
allocates
System
View: what
problems
doesresources
it solve? among running programs. It
controls the sharing of resources among programs.
Implementation View: how is it built?
¯ The OS itself also uses resources, which it must share with application
programs.
Implementation View: The OS is a concurrent, real-time program.
An operating system is part cop, part facilitator.
¯ Concurrency arises naturally in an OS when it supports concurrent
applications, and because it must interact directly with the hardware.
¯ Hardware interactions also impose timing constraints.
CS350
Operating Systems
Fall 2005
Intro
42
Application
Schematic View
Viewof
ofan
anOperating
OperatingSystem
System
User Programs
¯ The OS provides an execution environment for running programs.
system call
system
calls
– The execution
environment
provides a program
results with the processor time
and memory space that it needs to run.
system call interface
– The execution environment provides interfaces through which a program
can use networks, storage, I/O devices, and other system hardware
Operating System
components.
£ Interfaces provide a simplified, abstract view of hardware to application
programs.
commands
data and interrupts
and data
– The execution environment isolates running programs from one another
and prevents undesirable interactions among them.
Resources
CS350
Operating Systems
Fall 2005
Intro
531
Other
Operating
What
Views
is anof
System
Operating
an Operating
Abstractions
System?
System
System View: The OS manages the hardware resources of a computer system.
¯ The execution environment provided by the OS includes a variety of abstract
¯ Resources include processors, memory, disks and other storage devices,
entities that can be manipulated by a running program. Examples:
network
I/O devices
¯ Three
viewsinterfaces,
of an operating
systemsuch as keyboards, mice and monitors, and
filessoand
systems: abstract view of secondary storage
on.file View:
Application
what services does it provide?
address
spaces:
abstract
view of primary
memory
¯ The operating
system
allocates
System
View: what
problems
doesresources
it solve? among running programs. It
processes,
abstract
view ofamong
program
execution
controlsthreads:
the sharing
of resources
programs.
Implementation View: how is it built?
sockets,
pipes:
view
of network
or it
other
channels
¯ The OS
itselfabstract
also uses
resources,
which
mustmessage
share with
application
programs.
¯ This course will cover
Implementation
The OS
a concurrent,
real-time
program.
– why theseView:
abstractions
areisdesigned
the way
they are
An operating system is part cop, part facilitator.
arises naturally
in an OS when
it supportsprograms
concurrent
–¯ Concurrency
how these abstractions
are manipulated
by application
applications, and because it must interact directly with the hardware.
– how these abstractions are implemented by the OS
¯ Hardware interactions also impose timing constraints.
CS350
Operating Systems
Fall 2005
Intro
642
Application
Schematic View
View
Course
of
ofan
an
Outline
Operating
OperatingSystem
System
User Programs
¯ Introduction
¯ The OS provides an execution environment for running programs.
¯ Processes and Threads
system call
system
calls
– The execution
environment
provides a program
results with the processor time
¯ Concurrency
andspace
Synchronization
and memory
that it needs to run.
system call interface
– The execution
environment
provides interfaces through which a program
¯ Address
Spaces and
Virtual Memory
can use networks, storage, I/O devices, and other system hardware
¯ Scheduling
Operating System
components.
¯ Devices
and Device
Management
£ Interfaces
provide
a simplified, abstract view of hardware to application
programs.
commands
¯ File Systems
data and interrupts
and data
– The execution environment isolates running programs from one another
¯ Interprocess Communication and Networking
and prevents undesirable interactions among them.
¯ Security
Resources
CS350
Operating Systems
Fall 2005
Intro
531
Other
Operating
What
Views
is anof
System
Operating
an Operating
Abstractions
System?
System
System View: The OS manages the hardware resources of a computer system.
¯ The execution environment provided by the OS includes a variety of abstract
¯ Resources include processors, memory, disks and other storage devices,
entities that can be manipulated by a running program. Examples:
network
I/O devices
¯ Three
viewsinterfaces,
of an operating
systemsuch as keyboards, mice and monitors, and
filessoand
systems: abstract view of secondary storage
on.file View:
Application
what services does it provide?
address
spaces:
abstract
view of primary
memory
¯ The operating
system
allocates
System
View: what
problems
doesresources
it solve? among running programs. It
processes,
abstract
view ofamong
program
execution
controlsthreads:
the sharing
of resources
programs.
Implementation View: how is it built?
sockets,
pipes:
view
of network
or it
other
channels
¯ The OS
itselfabstract
also uses
resources,
which
mustmessage
share with
application
programs.
¯ This course will cover
Implementation
The OS
a concurrent,
real-time
program.
– why theseView:
abstractions
areisdesigned
the way
they are
An operating system is part cop, part facilitator.
arises naturally
in an OS when
it supportsprograms
concurrent
–¯ Concurrency
how these abstractions
are manipulated
by application
applications, and because it must interact directly with the hardware.
– how these abstractions are implemented by the OS
¯ Hardware interactions also impose timing constraints.
CS350
Operating Systems
Fall 2005
Intro
642
Application
Schematic View
View
Course
of
ofan
an
Outline
Operating
OperatingSystem
System
User Programs
¯ Introduction
¯ The OS provides an execution environment for running programs.
¯ Processes and Threads
system call
system
calls
– The execution
environment
provides a program
results with the processor time
¯ Concurrency
andspace
Synchronization
and memory
that it needs to run.
system call interface
– The execution
environment
provides interfaces through which a program
¯ Address
Spaces and
Virtual Memory
can use networks, storage, I/O devices, and other system hardware
¯ Scheduling
Operating System
components.
¯ Devices
and Device
Management
£ Interfaces
provide
a simplified, abstract view of hardware to application
programs.
commands
¯ File Systems
data and interrupts
and data
– The execution environment isolates running programs from one another
¯ Interprocess Communication and Networking
and prevents undesirable interactions among them.
¯ Security
Resources
CS350
Operating Systems
Fall 2005