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Auflistung nach Autor:in "Gerhards, Rainer"

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  • Zeitschriftenartikel
    Minimizing Energy Cost in Task-Graph Execution on Parallel Platforms
    (PARS-Mitteilungen: Vol. 34, Nr. 1, 2017) Gerhards, Rainer; Keller, Jörg
    We investigate minimization of energy cost for execution of statically scheduled task graphs on parallel machines with frequency scaling and given deadlines, assuming that the power profile of the processing elements and the energy price curve over time is known or can be predicted. We present both a mixed integer linear program and a heuristic to solve this problem, using time slots of fixed lengths and discrete frequency levels for both approaches and a fixed budget per time slot for the heuristic. We evaluate the heuristic by comparison to cost-optimal schedules. For price curves occurring in practice, and for deadlines not too close to the minimum makespan, the heuristic produces about 15% more energy cost than the optimal solution.
  • Zeitschriftenartikel
    Peelsched: a Simple and Parallel Scheduling Algorithm for Static Taskgraphs
    (PARS: Parallel-Algorithmen, -Rechnerstrukturen und -Systemsoftware: Vol. 28, No. 1, 2011) Keller, Jörg; Gerhards, Rainer
    We present a new algorithm, which we call P EELSCHED, to schedule a set of tasks with precedence constraints and communication costs onto a parallel computer with homogeneous processing units. The algorithm is deterministic and simple, and can be parallelized itself. The new algorithm is based on the usage of structural graph properties, in particular series-parallel or N-free graphs, but can be used on any DAG. We provide an implementation and validate it against a benchmark suite of task graphs. We find that the algorithm's scheduling results are comparable to strictly sequential schedulers.