Architecture-Neutral Operating System Components Daniel Lohmann - - PowerPoint PPT Presentation

Daniel Lohmann

Department of Computer Science IV Distributed Systems and Operating Systems Friedrich-Alexander University Erlangen-Nuremberg http://www4.informatik.uni-erlangen.de/~lohmann daniel.lohmann@informatik.uni-erlangen.de

Architecture-Neutral Operating System Components

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daniel.lohmann@informatik.uni-erlangen.de

The Tyranny of OS Architectures

Architecture defines fundamental properties and policies

Module structure and interaction schemes Scheduling and locking strategies Interrupt handling and synchronization Supported hardware platforms …

Architecture is usually considered as something static

Decisions are made at early stages of OS development Extremely costly to adapt later

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daniel.lohmann@informatik.uni-erlangen.de

But why... shouldn’t it be possible to configure architectural properties?

Optimize a server OS for a dedicated services demands

Database / network / internet service

Taylor down an embedded systems OS

Often very specific application demands

and extreme resource constraints

Cope better with architectural evolution

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daniel.lohmann@informatik.uni-erlangen.de

Interaction

The Problem

Architectural properties are inherent crosscutting

Synchronisation

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daniel.lohmann@informatik.uni-erlangen.de

Aspect-Oriented Programming

AOP has proven to be successful in

dealing with crosscutting concerns

With AspectC++ it is now possible to investigate

the benefits for system software development

Synchronisation Interaction

Component B Component C Component A

OS Component Code Aspect Code

«uses»

Aspect Weaver

http://www.aspectc.org

«uses»

Component B Component C Component A

Generated OS Code

«uses» «uses»

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daniel.lohmann@informatik.uni-erlangen.de

The CiAO Project (CiAO is Aspect Oriented)

Aspect-oriented family of operating systems

Designed in an aspect-oriented manner Full encapsulation of policies and architectural properties

Target: Embedded Systems

From deeply-embedded devices up to embedded UNIX systems High level of adaptability and configurability

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daniel.lohmann@informatik.uni-erlangen.de

The CiAO Vision: Architectural Transparency

Abstract Model

Component B Component C

«uses» «uses»

Component A

C

• m

p

• n

e n t s

Synchronisation Interaction

A s p e c t s

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daniel.lohmann@informatik.uni-erlangen.de

The CiAO Vision: Architectural Transparency

Configuration 1: Procedure based (monolithic)

Component B Component C Component A

C

• m

p

• n

e n t s

Synchronisation Interaction

A s p e c t s Semaphore Procedure call Call Call

address space

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daniel.lohmann@informatik.uni-erlangen.de

The CiAO Vision: Architectural Transparency

Configuration 2: Message oriented (threaded)

Component B Component C Component A

C

• m

p

• n

e n t s

Synchronisation Interaction

A s p e c t s «none» Message Message Message

address space

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daniel.lohmann@informatik.uni-erlangen.de

The CiAO Vision: Architectural Transparency

Configuration 3: Process oriented (µ-kernel)

Component B Component C Component A

C

• m

p

• n

e n t s

Synchronisation Interaction

A s p e c t s «none» IPC IPC IPC

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daniel.lohmann@informatik.uni-erlangen.de

Conclusion

Architectural properties are inherent crosscutting

Low configurability Hard to cope with architectural evolution

Aspect-Orientd Software Development can help here

AspectC++ brings AOP to the C/C++ world Evaluation of AOP concepts in system software development Encapsulation without sacrificing efficiency

Real chance to reach architectural transparency

Daniel Lohmann

Department of Computer Science IV Distributed Systems and Operating Systems Friedrich-Alexander University Erlangen-Nuremberg http://www4.informatik.uni-erlangen.de/~lohmann daniel.lohmann@informatik.uni-erlangen.de

Thanks for your attention!