Application of submodular optimization to single machine scheduling with controllable processing times subject to release dates and deadlines

In this paper, we study a scheduling problem on a single machine, provided that the jobs have individual release dates and deadlines, and the processing times are controllable. The objective is to find a feasible schedule that minimizes the total cost of reducing the processing times. We reformulate the problem in terms of maximizing a linear function over a submodular polyhedron intersected with a box. For the latter problem of submodular optimization, we develop a recursive decomposition algorithm and apply it to solving the single machine scheduling problem to achieve the best possible running time

A framework for realistic real-time walkthroughs in a VR distributed environment

Virtual and augmented reality (VR/AR) are increasingly being used in various business scenarios and are important driving forces in technology development. However the usage of these technologies in the home environment is restricted due to several factors including lack of low-cost (from the client point of view) highperformance solutions. In this paper we present a general client/server rendering architecture based on Real-Time concepts, including support for a wide range of client platforms and applications. The idea of focusing on the real-time behaviour of all components involved in distributed IP-based VR scenarios is new and has not been addressed before, except for simple sub-solutions. This is considered as “the most significant problem with the IP environment” [1]. Thus, the most important contribution of this research will be the holistic approach, in which networking, end-systems and rendering aspects are integrated into a cost-effective infrastructure for building distributed real-time VR applications on IP-based networks

Decomposition algorithms for submodular optimization with applications to parallel machine scheduling with controllable processing times

In this paper we present a decomposition algorithm for maximizing a linear function over a submodular polyhedron intersected with a box. Apart from this contribution to submodular optimization, our results extend the toolkit available in deterministic machine scheduling with controllable processing times. We demonstrate how this method can be applied to developing fast algorithms for minimizing total compression cost for preemptive schedules on parallel machines with respect to given release dates and a common deadline. Obtained scheduling algorithms are faster and easier to justify than those previously known in the scheduling literature

A comparison of CMS Tier0-dataflow scenarios using the Yasper simulation tool

The CMS experiment at CERN will produce large amounts of data in short time periods. Because the data buffers at the experiment are not large enough, this data needs to be transferred to other storages. The CMS Tier0 will be an enormous job processing and storage facility at the CERN site. One part of this Tier0, called the Tier0 input buffer, has the task to readout the experiment data buffers and to supply these data to other tasks that need to be carried out with it (such as storing). It has to make sure that no data is lost. This thesis compares different scenarios to work with a set of disk servers in order to accomplish the Tier0 input buffer tasks. To increase the performance per disk server, write and read actions on the same disk server are separated. To find the optimal moments a disk server should change from accepting and writing items to supplying items to other tasks, the combination of various parameters, such as the usage of a particular queuing discipline (like FIFO, LIFO, LPTF and SPTF) and the state of the disk server has been studied. To make the actual comparisons a simulation of dataflow models of the different scenarios has been used. These simulations have been performed with the Yasper simulation tool. This tool uses Petri Net models as its input. To be more certain that the models represent the real situation, some model parts have been remodelled in a tool called GPSS. This tool is not using Petri Nets as its input model; instead it uses queuing models described in a special GPSS language. The results of the simulations show that the best queuing discipline to be used with the Tier0 input buffer is the LPTF discipline. In particular in combination with a change moment as soon as a disk server has been readout completely