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A Framework for Integrating the RealTime Specification for Java and Java’s Remote Method Invocation
 In 5th IEEE International Symposium on ObjectOriented RealTime Distributed Computing (ISORC 2002
, 2002
"... This paper proposes a framework for integrating the RealTime Specification for Java and Java's Remote Method Invocation. The concepts of realtime remote and distributed realtime remote interfaces are introduced in order to facilitate the design and implementation of realtime and distributed ..."
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Cited by 23 (2 self)
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This paper proposes a framework for integrating the RealTime Specification for Java and Java's Remote Method Invocation. The concepts of realtime remote and distributed realtime remote interfaces are introduced in order to facilitate the design and implementation of realtime and distributed realtime threads that call remote objects. 1
EnergyEfficient, Utility Accrual RealTime Scheduling Under the Unimodal Arbitrary Arrival Model
 in ACM Design, Automation, and Test in Europe (DATE
, 2005
"... We present an energyefficient realtime scheduling algorithm called EUA∗, for the unimodal arbitrary arrival model (or UAM). UAM embodies a “stronger ” adversary than most arrival models. The algorithm considers application activities that are subject to time/utility function time constraints, UAM, ..."
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Cited by 23 (5 self)
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We present an energyefficient realtime scheduling algorithm called EUA∗, for the unimodal arbitrary arrival model (or UAM). UAM embodies a “stronger ” adversary than most arrival models. The algorithm considers application activities that are subject to time/utility function time constraints, UAM, and the multicriteria scheduling objective of probabilistically satisfying utility lower bounds, and maximizing systemlevel energy efficiency. Since the scheduling problem is intractable, EUA ∗ allocates CPU cycles, scales clock frequency, and heuristically computes schedules using statistical estimates of cycle demands, in polynomialtime. We establish that EUA ∗ achieves optimal timeliness during underloads, and identify the conditions under which timeliness assurances hold. Our simulation experiments illustrate EUA∗’s superiority. 1.
EnergyEfficient, Utility Accrual Scheduling under Resource Constraints for Mobile Embedded Systems
 in ACM International Conference on Embedded Software
, 2004
"... We present an energyefficient, utility accrual, realtime scheduling algorithm called the Resourceconstrained EnergyEfficient Utility Accrual Algorithm (or ReUA). ReUA considers an application model where activities are subject to time/utility function (TUF) time constraints, resource dependencie ..."
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Cited by 17 (9 self)
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We present an energyefficient, utility accrual, realtime scheduling algorithm called the Resourceconstrained EnergyEfficient Utility Accrual Algorithm (or ReUA). ReUA considers an application model where activities are subject to time/utility function (TUF) time constraints, resource dependencies including mutual exclusion constraints, and statistical performance requirements including activity (timeliness) utility bounds that are probabilistically satisfied. Further, ReUA targets mobile embedded systems where systemlevel energy consumption is also a major concern. For such a model, we consider the scheduling objectives of (1) satisfying the statistical performance requirements; and (2) maximizing the systemlevel energy efficiency. At the same time, resource dependencies must be respected. Since the problem is NPhard, ReUA makes resource allocations using statistical properties of application cycle demands and heuristically computes schedules with a polynomialtime cost. We analytically establish several timeliness and nontimeliness properties of the algorithm. Further, our simulation experiments illustrate the algorithm's effectiveness.
Utility accrual scheduling under arbitrary time/utility functions and multiunit resource constraints
 in IEEE RealTime and Embedded Computing Systems and Applications
, 2004
"... Abstract. We present a uniprocessor realtime scheduling algorithm called Resourcecontrainted Utility Accrual algorithm (or RUA). RUA considers an application model, where activities can be subject to arbitrarilyshaped time/utility function (TUF) time constraints and resource constraints including ..."
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Cited by 16 (8 self)
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Abstract. We present a uniprocessor realtime scheduling algorithm called Resourcecontrainted Utility Accrual algorithm (or RUA). RUA considers an application model, where activities can be subject to arbitrarilyshaped time/utility function (TUF) time constraints and resource constraints including mutual exclusion under a multiunit resource request model. For such a model, we consider the scheduling objective of maximizing the total utility accrued by all activities. This problem was previously open. Since the problem is N Phard, RUA heuristically computes schedules with a polynomialtime cost. We analytically establish several timeliness and nontimeliness properties of the algorithm, including upper bound on blocking time (under multiunit request model) and deadlockfreedom. We also implement RUA on a POSIX RTOS and conduct experimental comparisons with other TUF scheduling algorithms that address a subset of RUA’s model. Our implementation measurements show that RUA performs generally better than, or as good as, other TUF algorithms for the applicable cases. 1
Adaptive timecritical resource management using time/utility functions: Past, present, and future
 In Proceedings of the 28th Annual International Computer Software and Applications Conference
, 2004
"... Time/utility function time constraints (or TUFs) and utility accrual (UA) scheduling optimality criteria, constitute, arguably, the most effective and broadest approach for adaptive, dynamic timecritical resource management. A TUF, which is a generalization of the classical deadline constraint, spe ..."
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Cited by 13 (0 self)
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Time/utility function time constraints (or TUFs) and utility accrual (UA) scheduling optimality criteria, constitute, arguably, the most effective and broadest approach for adaptive, dynamic timecritical resource management. A TUF, which is a generalization of the classical deadline constraint, specifies the utility of completing an application activity as an applicationor situationspecific function of that activity’s completion time. With TUF time constraints, timeliness optimality criteria can be specified in terms of accrued (e.g., summed) activity utilities. This paper overviews past and recent advances on adaptive resource management for dynamic timecritical systems using UA algorithms. Emerging challenges and new research directions are also identified. 1.
Lockfree synchronization for dynamic embedded realtime software
 In ACM/IEEE Design, Automation, and Test in Europe (DATE
, 2006
"... We consider nonblocking synchronization for dynamic embedded realtime systems such as those that are subject to resource overloads and arbitrary activity arrivals. The multiwriter/multireader problem inherently occurs in such systems, when their activities must concurrently and mutually exclusiv ..."
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Cited by 10 (2 self)
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We consider nonblocking synchronization for dynamic embedded realtime systems such as those that are subject to resource overloads and arbitrary activity arrivals. The multiwriter/multireader problem inherently occurs in such systems, when their activities must concurrently and mutually exclusive share data objects. We consider lockfree synchronization for this problem under the unimodal arbitrary arrival model (or UAM). UAM embodies a “stronger” adversary than most traditional arrival models. We establish the fundamental tradeoffs between lockfree and lockbased object sharing under UAM — the first such result. Our tradeoffs include analytical conditions under which activities ’ accrued timeliness utility is greater under lockfree than lockbased, and the consequent upper bound on the increase in accrued utility. Our implementation experience on a POSIX RTOS reveals that the lockfree scheduling algorithm yields higher accrued utility, by as much as 65%, and critical time satisfactions, by as much as 80%, over lockbased. 1.
On multiprocessor utility accrual realtime scheduling with statistical timing assurances
 In IFIP Embedded and Ubiquitous Computing (EUC
, 2006
"... We present the first Utility Accrual (or UA) realtime scheduling algorithm for multiprocessors, called gMUA. The algorithm considers an application model where realtime activities are subject to time/utility function time constraints, variable execution time demands, and resource overloads where t ..."
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Cited by 9 (1 self)
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We present the first Utility Accrual (or UA) realtime scheduling algorithm for multiprocessors, called gMUA. The algorithm considers an application model where realtime activities are subject to time/utility function time constraints, variable execution time demands, and resource overloads where the total activity utilization demand exceeds the total capacity of all processors. We consider the scheduling objective of (1) probabilistically satisfying lower bounds on each activity’s maximum utility and (2) maximizing the systemwide, total accrued utility. We establish several properties of gMUA including optimal total utility (for a special case), conditions under which individual activity utility lower bounds are satisfied, a lower bound on systemwide total accrued utility, and bounded sensitivity for assurances to variations in execution time demand estimates. Our simulation experiments validate our analytical results and confirm the algorithm’s effectiveness and superiority.
Scheduling distributable realtime threads in Tempus middleware
 In IEEE Conference on Parallel and Distributed Systems
, 2004
"... We present the Tempus realtime middleware. Tempus supports RealTime CORBA 2.0’s distributable threads (DTs) as an endtoend programming abstraction for distributed realtime systems. DTs in Tempus can have time constraints, including time/utility functions (TUFs), can have resource constraints, p ..."
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Cited by 7 (4 self)
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We present the Tempus realtime middleware. Tempus supports RealTime CORBA 2.0’s distributable threads (DTs) as an endtoend programming abstraction for distributed realtime systems. DTs in Tempus can have time constraints, including time/utility functions (TUFs), can have resource constraints, particularly mutual exclusion, and can be scheduled according to utility accrual (UA) disciplines. Tempus propagates the scheduling parameters of DT’s as they transit objects and hence perhaps node boundaries. Nodelocal instances of a UA scheduling algorithm use the propagated parameters to construct local schedules and resolve resource dependencies for local timeliness optimization, toward approximate, systemwide timeliness optimality. Tempus uses an applicationlevel scheduling framework for nodelocal TUF/UA scheduling on realtime POSIXcompliant operating systems. Our experimental measurements demonstrate the effectiveness of the middleware in scheduling DTs. Index Terms distributable thread, time/utility function, distributed scheduling, shared resource access, mutual exclusion, RealTime CORBA 2.0 I.
On distributed realtime scheduling in networked embedded systems in the presence of crash failures
 in Proceedings of SEUS 2007
, 2007
"... Abstract. We consider the problem of scheduling distributable realtime threads in networked embedded systems that operate under runtime uncertainties including those on thread execution times, thread arrivals, and node failure occurrences. We present a distributed scheduling algorithm called CUA. ..."
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Cited by 6 (5 self)
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Abstract. We consider the problem of scheduling distributable realtime threads in networked embedded systems that operate under runtime uncertainties including those on thread execution times, thread arrivals, and node failure occurrences. We present a distributed scheduling algorithm called CUA. We show that CUA satisfies thread time constraints in the presence of crash failures, is earlydeciding, has an efficient message complexity of O(fn) (where f is the number of crashes that actually occur and n is the number of nodes), and is timeoptimal with a time lower bound of O(D + fd + nk) (where D is the message delay upper bound, d is the failure detection bound, and k is the maximum number of threads). In crashfree runs, the algorithm constructs schedules within O(D + nk), and yields optimal total utility if nodes are also not overloaded. The algorithm is also “besteffort ” in that a high importance thread that may arrive at any time has a very high likelihood for feasible completion (in contrast to classical admission control algorithms which favor feasible completion of admitted threads over admitting new ones, irrespective of thread importance). 1
On scheduling garbage collector in dynamic realtime systems with statistical timing assurances
 In IEEE ISORC
, 2006
"... We consider garbage collection (GC) in dynamic realtime systems. We consider the timebased GC approach of running the collector as a separate, concurrent thread, and focus on realtime scheduling to obtain assurances on mutator timing behavior, while ensuring that memory is never exhausted. We pre ..."
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Cited by 5 (1 self)
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We consider garbage collection (GC) in dynamic realtime systems. We consider the timebased GC approach of running the collector as a separate, concurrent thread, and focus on realtime scheduling to obtain assurances on mutator timing behavior, while ensuring that memory is never exhausted. We present a scheduling algorithm called GCUA. The algorithm considers mutator activities that are subject to time/utility function time constraints, variable execution time demands, the unimodal arbitrary arrival model that allows a strong adversary, and resource overloads. We establish several properties of GCUA including probabilisticallysatisfied utility lower bounds for each mutator activity, a lower bound on the systemwide total accrued utility, bounded sensitivity for the assurances to variations in mutator execution time demand estimates, and no memory exhaustion at all times. Our simulation experiments validate our analytical results and confirm the algorithm’s effectiveness and superiority. I.