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Biasing Effects in Schedulability Measures

Biasing Effects in Schedulability Measures,10.1109/ECRTS.2004.7,Enrico Bini,Giorgio C. Buttazzo

Biasing Effects in Schedulability Measures   (Citations: 39)
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The performance of a schedulabilty test is typically eval- uated by generating a huge number of synthetic task sets and then computing the fraction of those that pass the test with respect to the total number of feasible ones. The result- ing ratio, however, depends on the metrics used for evaluat- ing the performance and on the method for generating ran- dom task parameters. In particular, an important factor that affects the overall result of the simulation is the probability density function of the random variables used to generate the task set parameters. In this paper we discuss and compare three different metrics that can be used for evaluating the performance of schedulability tests. Then, we investigate how the ran- dom generation procedure can bias the simulation results of some specific scheduling algorithm. Finally, we present an efficient method for generating task sets with uniform distribution in a given space, and show how some intuitive solutions typically used for task set generation can bias the simulation results.
Conference: Euromicro Conference on Real-Time Systems - ECRTS , pp. 196-203, 2004
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    • ...Several task set generation algorithms are discussed in [10]...
    • ...An efficient method for generating task sets is UUnifast algorithm [10] which generates utilization values having uniform distribution...
    • ...It keeps generating sum of n-i random values, where i varies from 1 to n-1, and sets Ui as the difference between the previous sum and the generated sum [10]...

    A. Arya Paulet al. Reducing the Number of Context Switches in Real Time Systems

    • ...For each utilization value Ui = i m where i2 [0:025; 0:05;:::; 0:975], we randomly generate a set of tasksets for which the utilization U( ) = Ui. The generation of the taskset is based on the algorithm UUnifast [17]...

    Frederic Fauberteauet al. Laxity-based restricted-migration scheduling

    • ...While several algorithms for task generation have been proposed ([1],[2],[6]), we are not aware of a library or software package dedicated to task generation...
    • ...Tasks can be generated by combining task periods with execution times, randomly or based on certain algorithms like the ‘UUniFast ‘algorithm [2] • Schedulability Tests: Several schedulability tests for different execution models have been developed over the past several years, like the popular schedulability test of Liu and Layland’s [7] and Bini et al [3] • Satisfiability Tests: Under satisfiability condition we allow researchers to ...

    Chaitanya Belwalet al. An Extensible Framework for Real-Time Task Generation and Simulation

    • ...Schedulability versus utilization: For schedulability curves with respect to the utilization, we first generated a random set of task utilizations ui with UUniFast [19], [20]...
    • ...pi , we considered a processor utilization of 40% (i.e., U = 0.4) and used UUniFast [19], [20] to obtain a set of task utilizations ui. Again, the periods were obtained with a uniform distribution in [0,1] and the execution times were computed just as before ei = uipi...

    Alejandro Masruret al. Near-Optimal Constant-Time Admission Control for DM Tasks via Non-unif...

    • ...UUniFast algorithm, described in [5], was used to generate each set of n tasks with individual utilizations uniformly distributed with a given total utilization Utot...

    Marko Bertognaet al. Preemption Points Placement for Sporadic Task Sets

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