transparent synchronization protocols for compositional real-time systems.pdf
TRANSCRIPT
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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