HPC Cloud for Scientific and Business Applications: Taxonomy, Vision, and Research Challenges

High Performance Computing (HPC) clouds are becoming an alternative to on-premise clusters for executing scientific applications and business analytics services. Most research efforts in HPC cloud aim to understand the cost-benefit of moving resource-intensive applications from on-premise environments to public cloud platforms. Industry trends show hybrid environments are the natural path to get the best of the on-premise and cloud resources---steady (and sensitive) workloads can run on on-premise resources and peak demand can leverage remote resources in a pay-as-you-go manner. Nevertheless, there are plenty of questions to be answered in HPC cloud, which range from how to extract the best performance of an unknown underlying platform to what services are essential to make its usage easier. Moreover, the discussion on the right pricing and contractual models to fit small and large users is relevant for the sustainability of HPC clouds. This paper brings a survey and taxonomy of efforts in HPC cloud and a vision on what we believe is ahead of us, including a set of research challenges that, once tackled, can help advance businesses and scientific discoveries. This becomes particularly relevant due to the fast increasing wave of new HPC applications coming from big data and artificial intelligence.Comment: 29 pages, 5 figures, Published in ACM Computing Surveys (CSUR

Optimising resource costs of cloud computing for education

International audienceThere is a growing interest around the utilisation of cloud computing in education. As organisations involved in the area typically face severe budget restrictions, there is a need for cost optimisation mechanisms that explore unique features of digital learning environments. In this work, we introduce a method based on Maximum Likelihood Estimation that considers heterogeneity of IT infrastructure in order to devise resource allocation plans that maximise platform utilisation for educational environments. We performed experiments using modelled datasets from real digital teaching solutions and obtained cost reductions of up to 30%, compared with conservative resource allocation strategies

Impact of User Patience on Auto-Scaling Resource Capacity for Cloud Services

International audienceAn important feature of most cloud computing solutions is auto-scaling, an operation that enables dynamic changes on resource capacity. Auto-scaling algorithms generally take into account aspects such as system load and response time to determine when and by how much a resource pool capacity should be extended or shrunk. In this article, we propose a scheduling algorithm and auto-scaling triggering strategies that explore user patience, a metric that estimates the perception end-users have from the Quality of Service (QoS) delivered by a service provider based on the ratio between expected and actual response times for each request. The proposed strategies help reduce costs with resource allocation while maintaining perceived QoS at adequate levels. Results show reductions on resource-hour consumption by up to approximately 9% compared to traditional approaches

Tratamento endovascular para pacientes portadores de Claudicação Intermitente que não melhoram com tratamento clínico

PURPOSE: To study the results including long-term follow-up obtained with endovascular treatment of patients with intermittent claudication who did not experience clinical improvement with conservative treatment. METHODS: From January 1992 to January 2002, 62 of 1380 patients (4.5%) with intermittent claudication underwent endovascular treatment and were followed up for up to 120 months (mean 76 months). The variables analyzed were the functioning of the arterial segment undergoing the endovascular procedure, the evolution of the maximum walking distance, and incidence of related morbidity and mortality. RESULTS: Fifty-two patients (84%) experienced no walking limitation after the procedure, and 6 patients (10%) improved but still exhibited some degree of limitation, for a total improved outcome of 94%. The patency rate was 82%. There was no intraoperative mortality. One primary failure and one immediate thrombosis occurred, and both were surgically corrected. Thrombosis of the treated artery occurred in 6 patients 12, 16, 25, 29, 62, and 66 months after the procedure. These patients started to experience intermittent claudication with a walking distance to onset that was similar to their presurgical distance to onset. During follow-up, a mortality rate of 12.9% (8 patients) was observed, 6 due to myocardial infarctions and 2 due cerebral infarction. Three patients underwent coronary bypasses 22, 36, and 55 months after the endovascular surgery, and 2 patients underwent coronary angioplasty after 6 and 26 months. The mean follow up period was 76 months (range 0-120 months). CONCLUSION: This study shows that endovascular treatment of intermittent claudication brought about a lasting regression of the ischemic conditions in a significant number of patients, with excellent patency rates. It was concluded that this is a good alternative for selected patients, with low rates of complications and positive long-term results.OBJETIVO: Estudar a longo prazo (média de 76 meses de seguimento) os resultados obtidos com o tratamento endovascular em pacientes que não melhoram com o tratamento clínico, MÉTODOS: De Janeiro de 1992 a Janeiro de 2002, 62 pacientes de um grupo de 1380 claudicantes foram submetidos a tratamento endovascular, representando 4,5% do total. As variáveis analisadas foram o funcionamento do segmento arterial submetido ao procedimento endovascular, a evolução da distância máxima de marcha e a ocorrência de morbi-mortalidade. RESULTADOS: Cinqüenta e dois (84%) pacientes não apresentaram restrições à deambulação após o procedimento. Seis pacientes melhoraram, representando um benefício de 94%. Não houve mortalidade intra-operatória. Uma falência primária e uma trombose imediata foram corrigidas cirurgicamente. Seis pacientes apresentaram trombose da artéria tratada 12, 16, 25, 29, 62 e 66 meses após o procedimento e voltaram a apresentar Claudicação Intermitente para as mesmas distâncias referidas antes da cirurgia. Durante o seguimento foi observada taxa de mortalidade de 12,9% (8 pacientes), dos quais 6 por infarto do miocárdio e dois por acidente vascular cerebral. Três pacientes foram submetidos à revascularização miocárdica 22, 36 e 55 meses após o procedimento endovascular e duas angioplastias foram realizadas com 6 e 26 meses de seguimento. O tempo médio de segmento foi de 76 meses (0 a 120 meses). CONCLUSÃO: O tratamento endovascular da Claudicação Intermitente levou a melhora das condições da marcha em um número significativo de pacientes, com excelentes taxas de patência (82,0%). Concluímos que esta é uma boa alternativa para determinados pacientes, com poucas complicações e resultados positivos a longo prazo

Scheduling moldable {BSP} tasks

Our main goal in this paper is to study the scheduling of parallel BSP tasks on clusters of computers. We focus our attention on special characteristics of BSP tasks, which can use less processors than the original required, but with a particular cost model. We discuss the problem of scheduling a batch of BSP tasks on a fixed number of computers. The objective is to minimize the completion time of the last task (makespan). We show that the problem is difficult and present approximation algorithms and heuristics. We finish the paper presenting the results of extensive simulations under different workloads