Advanced operating systems
Download
1 / 37

Advanced Operating Systems - PowerPoint PPT Presentation


  • 167 Views
  • Uploaded on
  • Presentation posted in: General

Advanced Operating Systems. Welcome to this course, in Fall Semester 1389-90 Main TextBooks 1- Tanenbaum’s book 2- Chow’s Book 3- Singhal’s Book Other extra references: 1- Attieh’s book 2- Lynch’s book. Advanced Operating Systems. Assistants: to be announced. Evaluation:

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha

Download Presentation

Advanced Operating Systems

An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -

Presentation Transcript


Advanced Operating Systems

  • Welcome to this course, in Fall Semester 1389-90

  • Main TextBooks

    1- Tanenbaum’s book

    2- Chow’s Book

    3- Singhal’s Book

  • Other extra references:

    1- Attieh’s book

    2- Lynch’s book

OS2-Sharif University of Technology - Sem1-89-90; R. Jalili


Advanced Operating Systems

  • Assistants: to be announced.

  • Evaluation:

    • Mid-Term Exam

    • Project

    • Review Paper

    • Final Exam

  • The course Home page and Mailing-list …

  • Office Hours: Sunday and Tuesday 8 - 9

OS2-Sharif University of Technology - Sem1-89-90; R. Jalili


1Introduction to Distributed Systems and Distributed Operating Systems (DOSs)(From Tanenbaum’sBook)

OS2-Sharif University of Technology - Sem1-89-90; R. Jalili


Definition of a Distributed System (1)

A distributed system is:

A collection of independent computers that appears to its users as a single coherent system.

OS2-Sharif University of Technology - Sem1-89-90; R. Jalili


Definition of a Distributed System (2)

1.1

A distributed system organized as middleware.Note that the middleware layer extends over multiple machines.


Goals in DSs

  • Connecting Users and Resources

  • Transparency

  • Openness

  • Scalability

    Will be discussed in the next slides.

OS2-Sharif University of Technology - Sem1-89-90; R. Jalili


Transparency in Distributed Systems

Different forms of transparency in a distributed system.


Degree of Transparency

  • Is transparency good anytime and everywhere?

  • Tradeoff between transparency and performance.

    - Updating a replicated database!

OS2-Sharif University of Technology - Sem1-89-90; R. Jalili


Openness

  • Offering services based on standards.

  • Services are specified through interfaces, described in IDL (Interface Definition Language)

  • Interoperability: two implementations of a system to co-exist and work together; or

    multiple systems developed by different vendors to be able to work with each other.

  • Portability: An application developed to work on A can be executed on another system B.

  • Separating policy from mechanism

OS2-Sharif University of Technology - Sem1-89-90; R. Jalili


Scalability

  • Definition of an scalable system?

  • 3 different dimensions

    • Size: Adding more users and resources to the system.

    • Geography: Users and resources can lie far apart.

    • Administration: Many administration organization!

OS2-Sharif University of Technology - Sem1-89-90; R. Jalili


Scalability Obstacles

Examples of scalability limitations.


Scalability Solutions

  • Hiding communication latencies: try to avoid waiting for responses to remote service requests  Use Asynchronous Communication

    • Many applications cannot run on an asynch communication system

    • Next slide example.

  • Distribution: DNS as example

  • Replication: Caching and consistency!

OS2-Sharif University of Technology - Sem1-89-90; R. Jalili


Scaling Techniques (1)

1.4

  • The difference between letting:

  • a server or

  • a client check forms as they are being filled


Scaling Techniques (2)

1.5

An example of dividing the DNS name space into zones.


Hardware Concepts

1.6

Different basic organizations and memories in distributed computer

systems


Multiprocessors

A bus-based multiprocessor.

1.7

  • Memory is Coherent.

  • The bus is overloaded.

  • Caching: hit-rate?

  • Scalability?

OS2-Sharif University of Technology - Sem1-89-90; R. Jalili


Software Concepts

An overview of

  • DOS (Distributed Operating Systems)

  • NOS (Network Operating Systems)

  • Middleware

OS2-Sharif University of Technology - Sem1-89-90; R. Jalili


Uniprocessor Operating Systems

Separating applications from operating system code through

a microkernel.

1.11

OS2-Sharif University of Technology - Sem1-89-90; R. Jalili


Multiprocessor Operating Systems (1)

A monitor to protect an integer against concurrent access.

monitor Counter {

private:

int count = 0;

public:

int value() { return count;}

void incr () { count = count + 1;}

void decr() { count = count – 1;}

}

OS2-Sharif University of Technology - Sem1-89-90; R. Jalili


Multiprocessor Operating Systems (2)

A monitor to protect an integer against concurrent access, but

blocking a process.

monitor Counter {

private:

int count = 0;

int blocked_procs = 0;

condition unblocked;

public:

int value () { return count;}

void incr () {

if (blocked_procs == 0)

count = count + 1;

else

signal (unblocked);

}

void decr() {

if (count ==0) {

blocked_procs = blocked_procs + 1;

wait (unblocked);

blocked_procs = blocked_procs – 1;

}

else

count = count – 1;

}

}

OS2-Sharif University of Technology - Sem1-89-90; R. Jalili


Multicomputer Operating Systems (1)

General structure of a multicomputer operating system

Message Passing

1.14

OS2-Sharif University of Technology - Sem1-89-90; R. Jalili


Distributed Shared Memory Systems (1)

  • Pages of address space distributed among four machines

  • Situation after CPU 1 references page 10

  • Situation if page 10 is read only and replication is used

OS2-Sharif University of Technology - Sem1-89-90; R. Jalili


DSM – An Interesting Scenario!

False sharing of a page between two independent processes.

1.18

False Sharing!

OS2-Sharif University of Technology - Sem1-89-90; R. Jalili


Network Operating System (1)

General structure of a network operating system.

1-19

OS2-Sharif University of Technology - Sem1-89-90; R. Jalili


Network Operating System (2)

Two clients and a server in a network operating system.

1-20

OS2-Sharif University of Technology - Sem1-89-90; R. Jalili


Network Operating System (3)

Different clients may mount the servers in different places.

1.21

OS2-Sharif University of Technology - Sem1-89-90; R. Jalili


Positioning Middleware

General structure of a distributed system as middleware.

1-22

OS2-Sharif University of Technology - Sem1-89-90; R. Jalili


Middleware and Openness

In an open middleware-based distributed system, the protocols used by each middleware layer should be the same, as well as the interfaces they offer to applications.

1.23

OS2-Sharif University of Technology - Sem1-89-90; R. Jalili


Comparison between Systems

OS2-Sharif University of Technology - Sem1-89-90; R. Jalili


Clients and Servers

General interaction between a client and a server.

1.25

OS2-Sharif University of Technology - Sem1-89-90; R. Jalili


An Example Client and Server (1)

The header.h file used by the client and server.

OS2-Sharif University of Technology - Sem1-89-90; R. Jalili


An Example Client and Server (2)

A sample server.

OS2-Sharif University of Technology - Sem1-89-90; R. Jalili


An Example Client and Server (3)

A client using the server to copy a file.

1-27 b

OS2-Sharif University of Technology - Sem1-89-90; R. Jalili


Application Layering:Processing Level

The general organization of an Internet search engine into three different layers

1-28

OS2-Sharif University of Technology - Sem1-89-90; R. Jalili


Multitiered Architectures (1)

Alternative client-server organizations (a) – (e).

1-29

OS2-Sharif University of Technology - Sem1-89-90; R. Jalili


Multitiered Architectures (2)

An example of a server acting as a client.

1-30

OS2-Sharif University of Technology - Sem1-89-90; R. Jalili


Modern Architectures

An example of horizontal distribution of a Web service.

1-31

OS2-Sharif University of Technology - Sem1-89-90; R. Jalili


ad
  • Login