Browsing College of Computing and Information Sciences (CoCIS) by Author "Ngubiri, John"
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Characteristics of fairness metrics and their effect on perceived scheduler effectiveness
Ngubiri, John; van Vliet, Mario (2010)Parallel job schedulers are mostly evaluated using performance metrics. Deductions however can be misleading due to selective job starvation (unfairness). To choose a better scheduler, therefore, there is a need to compare ... -
Co-allocation with communication considerations in multi-cluster systems
Ngubiri, John; van Vliet, Mario (2008)Processor co-allocation can be of performance benefit. This is because breaking jobs into components reduces overall cluster fragmentation. However, the slower inter-cluster communication links increase job execution times. ... -
Computational resource optimization in Ugandan Tertiary Institutions
Ssekibuule, Richard; Lakuma, Joel; Ngubiri, John (Fountain Publishers, 2007)Insufficient computational power, caused by limited budgets is a big challenge to high quality research and education in developing countries. Some institutions suffer acute shortages while others enjoy comparatively more ... -
Computational resource optimization in Ugandan tertiary institutions
Ssekibuule, Richard; Lakuma, Joel; Ngubiri, John (Fountain Publishers Kampala, 2007)Insufficient computational power, caused by limited budgets is a big challenge to high quality research and education in developing countries. Some institutions suffer severe shortages while others enjoy comparatively ... -
The greedy multi-cluster scheduler: performance bounds and parametric sensitivity
Ngubiri, John; van Vliet, Mario (IJCIR, 2007)Most schedulers in parallel job scheduling do not put (job) schedulability into consideration when prioritizing jobs. Performance evaluation is mostly done using average values of the measurement metric. Using the average ... -
Group-wise performance evaluation of processor co-allocation in multi-cluster systems
Ngubiri, John; Van Vliet, Mario (Springer, 2007)Performance evaluation in multi-cluster processor co-allocation - like in many other parallel job scheduling problems - is mostly done by computing the average metric value for the entire job stream. This does not give a ... -
The Influence of Job Physical Characteristics on their Schedulability in Multi-cluster Systems
Ngubiri, John; van Vliet, Mario (Fountain Publishers, 2006)Performance (and sensitivity) studies in parallel job scheduling mostly use average values of the measurement metrics over the entire job stream. This does not give an idea of relative job performance (hence starvation) ... -
A Metric of fairness for parallel job schedulers
Ngubiri, John; van Vliet, Mario (Wiley Interscience, 2009-08-25)Fairness is an important aspect in queuing systems. Several fairness measures have been proposed in queuing systems in general and parallel job scheduling in particular. Generally, a scheduler is considered unfair if some ... -
On query optimization in relational databases
Ngubiri, John (2004-05)Query Optimization is an important process in Relational databases. With the current load on databases increasing, the need to optimize queries in batches is a promising way out. Studies have shown that sharing among common ... -
Performance, fairness and effectiveness in space slicing multi-cluster schedulers
Ngubiri, John; van Vliet, Mario (ACTA Press, 2007)Parallel job schedulers have mostly been evaluated/compared using performance metrics. The deductions, however, can be misleading due to selective starvation. This calls for studies in scheduler fairness. Most studies have ... -
Techniques and evaluation of processor co-allocation in multi-cluster systems
Ngubiri, John (2008-09-15)Computer processing power is increasing at a very high rate. A computer considered to be fast today may not be fast in a few years to come. At the same time, the number and complexity of resource intensive computer ... -
Using the greedy approach to schedule jobs on multi-cluster systems
Ngubiri, John; Van Vliet, Mario (WORLDCOMP 2006: The 2006 World Congress in Computer Science, Computer Engineering and Applied Computing, 2006)Clusters, multi-cluster systems and the grid are becoming popular high performance computing infrastructures. How jobs are scheduled on them greatly influence the performance. Since jobs are online in most computer systems, ...