Transparent Synchronization Protocols for Compositional Real-Time Systems.pdf

8/14/2019 Transparent Synchronization Protocols for Compositional Real-Time Systems.pdf

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Transparent SynchronizationProtocols for

Compositional Real-Time Systems

Martijn M. H. P. van den Heuvel, S, Reinder J. Bril,

and Johan J. Lukkien


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Introduction

Reuse hardware and software components

AUtomotive Open System ARchitecture(AUTOSAR)

OSEK(Open Systems and their Interfaces forthe Electronics in Motor Vehicles)-basedoperating system


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Not that easy!!

Global Shared Resources

Component Interaction

Synchronisation


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RELATED WORK


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Servers

Allocated Fraction of CPU time

Guaranteed Allocation

Temporal Firewall


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Stack Resource Policy

Preemption Level

For a task:For a Component:

Resource Ceiling

Global:

Local:


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Stack Resource Policy

System and Component Ceiling: Currentmax global/local resource ceiling

Preemption possible by task if itspreemption level is > Component Ceiling

Critical Sections


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Two-level HierarchicalScheduling Framework


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SYSTEM MODEL


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Component and Task Model

Component(C):

P:Period

Q:BudgetX:Set of max access time for global resource

Task(T):T:Period

E:WCET

D:Deadline


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Overrun

With payback

Without payback


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Microkernel

by Micrium

Open Source

Preemptive multitasking for upto 256 tasks

Size is configurable at compile time


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Timed Event Management

Relative timed event queues(RELTEQs)

Timers and Events

Activation Deactivation


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IMPLEMENTATION


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Structure of Global Resource

typedef struct resource

{

INT8U ceiling;INT8U lockingTask;

void* previous;

} Resource;


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Structure of Local Resource

typedef struct

{

resource globalResource;INT8U localCeiling;

INT8U localLockingTask;

void* previous;} localResource;


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Real-Time Scenario

Server

Budget

Resource


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SIRAP(subsystem integration& resource allocation policy)Bluto has taken away Olive.If Popoye has sufficientamount of Spinach he willfight bluto and take away

Olive else he will wait tillnext lot of Spinach arrives


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SIRAP(subsystem integration& resource allocation policy)


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Hierarchical Stack ResourcePolicy (HSRP)

Bluto has taken away Olive.If Popoye has sufficientamount of Spinach he willfight bluto and take away

Olive else he will call for backup and consume spinach

rom next u comin bud et


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Hierarchical Stack ResourcePolicy (HSRP)

B d d d l


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Bounded-delay resource openenvironment (BROE)

Bluto has taken away Olive.If Popoye has sufficientamount of Spinach he willfight bluto and take away

Olive else he will decrease thetime for arrival of next lot of

s inach B d d d l


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Bounded-delay resource openenvironment (BROE)


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EXPERIMENT & RESULTS


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Comparison


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DS 1 selects SIRAP and DS 2 selects HSRP with payback


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Conclusion

Memory requirements of these protocols arelower than priority-inheritance-basedprotocols

BROE and HSRP require expensive timeroperations in their primitives

SIRAP preferred for system having shorter

critical sections

Documents

Transparent Synchronization Protocols for Compositional Real-Time Systems.pdf