The paper we present here introduces a new priority mechanism in discrete-time queueing systems. It is a milder form of priority when compared to HoL priority, but it favors customers of one type over the other when compared to regular FCFS. It also provides an answer to the starvation problem that occurs in HoL priority systems. In this new priority mechanism, customers of different priority c...

We consider the mean delay optimization in the M/G/1 queue for service time distributions that have a tail with decresing hazard rate (DHR). If the DHR property is valid for the whole distribution, then it is known that the ForegroundBackground (FB) discipline, which gives full priority to the job with least amount of attained service, is optimal among nonanticipating scheduling disciplines. Ho...

Waiting systems for medical services have two distinctive features that differentiate them from queueing systems commonly studied in Operations Management: variability in the quality of service, and patient autonomy. That is, patients in these systems recognize that waiting has an option value and, hence, are willing to decline a service offer if they expect future offers to be more attractive....

Two-phase locking (2PL) is the concurrency control mechanism that is used in most commercial database systems. In 2PL, for a transaction to access a data item, it has to hold the appropriate lock (read or write) on the data item by issuing a lock request. While the way transactions set their lock requests and the way the requests are granted would certainly affect a system’s performance, such a...

BlueGene/L is a massively parallel cellular architecture system with a toroidal interconnect, currently being developed at the IBM T.J. Watson Research Center. Cellular architectures with a toroidal interconnect are effective at producing highly scalable computing systems, but typically require job partitions to be both rectangular and contiguous. These restrictions introduce fragmentation issu...

In modern resource management systems for supercomputers and HPC-clusters the job-scheduler plays a major role in improving the performance and usability of the system. The performance of the used scheduling policies (e.g. FCFS, SJF, LJF) depends on the characteristics of the queued jobs. Hence we developed the dynP scheduler family. The basic idea was to change between different scheduling pol...

Queueing for service occurs in technical applications as well as in common daily life, and scheduling should manage queues in a satisfactory way. Performance metrics are influenced by the service order, thus, scheduling policies should be designed with respect to the main performance metrics of interest. For human customers psychological effects and performance metrics other than delay play a c...

Adaptive space-sharing scheduling algorithms tend to improve the performance of clusters by allocating processors to jobs based on the current system load. The focus of existing adaptive algorithms is on dedicated homogeneous and heterogeneous clusters. However commodity clusters are naturally non-dedicated and tend to be heterogeneous over the time as cluster hardware is usually upgraded and n...