Mapping fine-grained power measurements to HPC application runtime characteristics on IBM POWER7

Optimization of energy consumption is a key issue for future HPC. Evaluation of energy consumption requires a fine-grained power measurement. Additional useful information is obtained when performing these measurements at component level. In this paper we describe a setup which allows to perform fine-grained power measurements up to a 1 ms resolution at component level on IBM POWER (IBM and POWER are trademarks of IBM in USA and/or other countries.) machines. We further developed a plug-in for VampirTrace that allows us to correlate these power measurements with application performance characteristics, e.g. obtained by hardware performance counters. This environment enables us to generate both power and performance profiles. Such profiles provide valuable input to develop future strategies for improving workload-driven energy usage per performance. We show in comparison with power profiles of coarser granularity that these fine-grained measurements are necessary to capture the dynamics of power switching

O contributo dos testes de software para a sua conceção mais eficiente do ponto de vista energético

Dissertação de Mestrado em Cidadania Ambiental e Participação apresentada à Universidade AbertaA mudança climática acelerada e adulterada pela humanização do planeta já não pode ser desmentida. A humanidade nas duas últimas centenas de anos desenvolveu uma tecnologia a que apelidou de “eletricidade” desde então moldou toda a sua vivência em torno desta tecnologia. Porém para a produzir “eletricidade” recorre-se, em boa medida à combustão de materiais que libertam CO2 em quantidades que pelo seu volume degradam o meio ambiente. Por outro lado, nem toda a humanidade tem acesso à “eletricidade” de forma abundante pelo que o seu consumo em determinadas zonas geográficas é racionado, impossibilitando assim que mais seres humanos entrem num melhor estado de desenvolvimento social. Esta dupla situação é confrontada com o facto de as sociedades contemporâneas utilizarem cada vez mais sistemas informáticos numa multiplicidade de tarefas diárias. Neste contexto, surgiu uma nova profissão denominada como Software Testing que tem como grande objetivo a validação e verificação da qualidade do software produzido. A vertente de consumo energético do software é um tema quase inexistente na comunidades de testers, pelo que esta dissertação pretende a) documentar o status quo do tema, b) demonstrar um método simples de apurar o consumo do software e, por último, c) demonstrar, por diversos meios, entre eles via fórmula matemática, que a partir de determinado ponto (não é só do ponto de vista ambiental pela redução da emissão de CO2) os testes ao consumo energético do software se devem realizar mas porque há retorno financeiro direto e imediato (pela redução de consumo de energia).Climate change cannot be ignored any longer. Not only this is a natural phenomenon but also it has been speeded up owing to human activities. To support most of those activities Humanity has developed a technology called "electricity". In the vast of majority of cases the generation of “electricity” is linked to the combustion of products that release CO2 into the atmosphere. On the other hand, not all countries has access to "electricity" in the same way – in an abundant way. In areas where its consumption is rationed human social development is delayed or even impaired. This situation is even more dramatic now-a-days since there is a multitude of human tasks that are dependent on electricity such as the use of personal computers which are now part of our daily life. In this context, a new professional category emerges – the software testing, which main objective is to verify and validate the quality of the software that is produced. The aspect of energy consumption by the software is not yet seen as important theme in our profession and that is why the present work aims at a) enlighten about the present situation, b) to reveal a simple method to measure software energy consumption and c) demonstrate by different ways, that after a certain point, the energy consumption it is not only important because of the environment (and quantity of CO2 release into the atmosphere) but also because of economical expenditur

A Unified Infrastructure for Monitoring and Tuning the Energy Efficiency of HPC Applications

High Performance Computing (HPC) has become an indispensable tool for the scientific community to perform simulations on models whose complexity would exceed the limits of a standard computer. An unfortunate trend concerning HPC systems is that their power consumption under high-demanding workloads increases. To counter this trend, hardware vendors have implemented power saving mechanisms in recent years, which has increased the variability in power demands of single nodes. These capabilities provide an opportunity to increase the energy efficiency of HPC applications. To utilize these hardware power saving mechanisms efficiently, their overhead must be analyzed. Furthermore, applications have to be examined for performance and energy efficiency issues, which can give hints for optimizations. This requires an infrastructure that is able to capture both, performance and power consumption information concurrently. The mechanisms that such an infrastructure would inherently support could further be used to implement a tool that is able to do both, measuring and tuning of energy efficiency. This thesis targets all steps in this process by making the following contributions: First, I provide a broad overview on different related fields. I list common performance measurement tools, power measurement infrastructures, hardware power saving capabilities, and tuning tools. Second, I lay out a model that can be used to define and describe energy efficiency tuning on program region scale. This model includes hardware and software dependent parameters. Hardware parameters include the runtime overhead and delay for switching power saving mechanisms as well as a contemplation of their scopes and the possible influence on application performance. Thus, in a third step, I present methods to evaluate common power saving mechanisms and list findings for different x86 processors. Software parameters include their performance and power consumption characteristics as well as the influence of power-saving mechanisms on these. To capture software parameters, an infrastructure for measuring performance and power consumption is necessary. With minor additions, the same infrastructure can later be used to tune software and hardware parameters. Thus, I lay out the structure for such an infrastructure and describe common components that are required for measuring and tuning. Based on that, I implement adequate interfaces that extend the functionality of contemporary performance measurement tools. Furthermore, I use these interfaces to conflate performance and power measurements and further process the gathered information for tuning. I conclude this work by demonstrating that the infrastructure can be used to manipulate power-saving mechanisms of contemporary x86 processors and increase the energy efficiency of HPC applications