Exact speedup factors and sub-optimality for non-preemptive scheduling

Exact speedup factors for linear-time schedulability tests for fixed-priority preemptive and non-preemptive scheduling

In this paper, we investigate the quality of several linear-time schedulability tests for preemptive and non-preemptive fixed-priority scheduling of uniprocessor systems. The metric used to assess the quality of these tests is the resource augmentation bound commonly known as the processor speedup factor. The speedup factor of a schedulability test corresponds to the smallest factor by which th...

An Optimization via Simulation approach for the preemptive and non-preemptive multi-mode resource-constrained project scheduling problems

In this paper a novel modelling and solving method has been developed to address the so-called resource constrained project scheduling problem (RCPSP) where project tasks have multiple modes and also the preemption of activities are allowed. To solve this NP-hard problem, a new general optimization via simulation (OvS) approach has been developed which is the main contribution of the current re...

On optimality of exact and approximation algorithms for scheduling problems

We consider the classical scheduling problem on parallel identical machines to minimize the makespan. Under the exponential time hypothesis (ETH), lower bounds on the running times of exact and approximation algorithms are characterized. We achieve the following results: (1) For scheduling on a constant number m of identical machines, denoted by Pm||Cmax, a fully polynomial time approximation s...

Preemptive and Non-Preemptive Real-Time Uni-Processor Scheduling

From Preemptive to Non-preemptive Speed-Scaling Scheduling

We are given a set of jobs, each one specified by its release date, its deadline and its processing volume (work), and a single (or a set of) speed-scalable processor(s). We adopt the standard model in speed-scaling in which if a processor runs at speed s then the energy consumption is s units of energy per time unit, where α > 1 is a small constant. Our goal is to find a schedule respecting th...