Refactoring software to heterogeneous parallel platforms

In summary, the papers included in this special issue are representative of the progress achieved by the research community at various levels from the very high level using parallel patterns to lower levels using, for example, transactional software memory. Also the integration of GPUs and FPGAs in the landscape is essential to achieve better performance in different categories of applications. All these innovative research directions will contribute to better achieve the long-term goal of better refactoring of existing applications to new and evolving parallel heterogeneous architectures

Improving performance and maintainability through refactoring in C++11

Abstraction based programming has been traditionally seen as an approach that improves software quality at the cost of losing performance. In this paper, we explore the cost of abstraction by transforming the PARSEC benchmark uidanimate application from low-level, hand-optimized C to a higher-level and more general C++ version that is a more direct representation of the algorithms. We eliminate global variables and constants, use vectors of a user-de ned particle type rather than vectors of built-in types, and separate the concurrency model from the application model. The result is a C++ program that is smaller, less complex, and measurably faster than the original. The benchmark was chosen to be representative of many applications and our transformations are systematic and based on principles. Consequently, our techniques can be used to improve the performance, exibility, and maintainability of a large class of programs. The handling of concurrency issues has been collected into a small new library, YAPL.J. Daniel Garcia's work was partially supported by Fundación CajaMadrid through their grant programme for Madrid University Professors. Bjarne Stroustrup's work was partially supported by NSF grant #083319

Optimización de carga de datos en un banco de pruebas de aviónica

Ponencias de las Decimocuartas Jornadas de Paralelismo de la Universidad Carlos III de Madrid celebradas el 15, 16 y 17 de septiembre de 2003 en Leganés, MadridEste artículo presenta las técnicas de optimización utilizadas para acelerar la carga de definiciones de señales de un banco de pruebas de aviónica. La carga de datos en formato XML puede presentar problemas de rendimiento cuando se trata de grandes volumenes de datos. Bajo esas condiciones, es necesario buscar alternativas que permitan cargar los datos de forma más eficiente, sin imponer restricciones a los generadores de los datos utilizados como entrada. El artículo analiza posibles optimizaciones y valora las ventajas e inconvenientes de cada solución.Publicad

Application Partitioning and Mapping Techniques for Heterogeneous Parallel Platforms

Proceedings of the First PhD Symposium on Sustainable Ultrascale Computing Systems (NESUS PhD 2016) Timisoara, Romania. February 8-11, 2016.Parallelism has become one of the most extended paradigms used to improve performance. Legacy source code needs to be re-written so that it can take advantage of multi-core and many-core computing devices, such as GPGPU, FPGA, DSP or specific accelerators. However, it forces software developers to adapt applications and coding mechanisms in order to exploit the available computing devices. It is a time consuming and error prone task that usually results in expensive and sub-optimal parallel software. In this work, we describe a parallel programming model, a set of annotating techniques and a static scheduling algorithm for parallel applications. Their purpose is to simplify the task of transforming sequential legacy code into parallel code capable of making full use of several different computing devices with the objetive of increasing performance, lowering energy consumption and increase the productivity of the developer.European Cooperation in Science and Technology. COSTThe work presented in this paper has been partially supported by EU under the COST programme Action IC1305, ’Network for Sustainable Ultrascale Computing (NESUS)’ The research leading to these results has received funding from the European Union Seventh Framework Programme (FP7/2007-2013) under grant agreement n. 609666 and by the Spanish Ministry of Economics and Competitiveness under the grant TIN2013-41350-P

A Highly Available Cluster of Web Servers with Increased Storage Capacity

Ponencias de las Decimoséptimas Jornadas de Paralelismo de la Universidad de Castilla-La Mancha celebradas el 18,19 y 20 de septiembre de 2006 en AlbaceteWeb servers scalability has been traditionally solved by improving software elements or increasing hardware resources of the server machine. Another approach has been the usage of distributed architectures. In such architectures, usually, file al- location strategy has been either full replication or full distribution. In previous works we have showed that partial replication offers a good balance between storage capacity and reliability. It offers much higher storage capacity while reliability may be kept at an equivalent level of that from fully replicated solutions. In this paper we present the architectural details of Web cluster solutions adapted to partial replication. We also show that partial replication does not imply a penalty in performance over classical fully replicated architectures. For evaluation purposes we have used a simulation model under the OMNeT++ framework and we use mean service time as a performance comparison metric.Publicad

Propuestas arquitectónicas para servidores Web distribuidos con réplicas parciales

En esta tesis se propone una arquitectura distribuida de servidor Web, basada en switch distribuido y replicación parcial de contenidos, que permite alcanzar una alta escalabilidad en cuanto a los volúmenes de datos manipulados sin que se produzca un deterioro en la fiabilidad del sistema resultante, haciendo posible además que la asignación de contenidos se adapte de forma dinámica a las necesidades del servicio. Más concretamente, las propuestas realizadas en esta tesis incluyen: Una familia novedosa de soluciones arquitectónicas de cluster Web con switch distribuido que satisface los objetivos de replicación parcial y distribución dinámica de réplicas, mitigando las debilidades relativas a la fiabilidad; un algoritmo de asignación de réplicas que hace que los elementos con mayor frecuencia de acceso sean replicados en más nodos servidores que los elementos con baja frecuencia de acceso; una estrategia de replicación dinámica de contenidos que permite determinar cuando es necesario realizar la redistribución de contenidos y cómo debe realizarse dicha redistribución; la adaptación de tres políticas de asignación de peticiones al caso de replicación parcial de contenidos: la política estática circular, la política de asignación al nodo menos cargado y la política de distribución de peticiones dependiente de la localidad de referencias (LARD). Las evaluaciones realizadas han demostrado que la fiabilidad de un sistema Web basado en cluster está limitada por la fiabilidad de su switch Web. Así mismo en esta tesis se demuestra que un sistema basado en replicación parcial que utilice un número relativamente bajo de réplicas ofrece una fiabilidad equivalente a la de un sistema totalmente replicado, aunque ofrece una capacidad de almacenamiento mucho mayor. Además, la replicación parcial no afecta negativamente al rendimiento global del sistemaIn this thesis a new Web server distributed architecture is proposed. The proposed architecture is based on the usage of a distributed switch and the partial replication of contents, in such a way that a high scalability can be achieved regarding managed data volume and without a reliability loss of the resulting system. Besides, content allocation may be adapted to service needs. The proposals presented in this thesis include: a new family of architecture solutions based on a Web cluster with distributed switch which satisfies the goals of partial replication and dynamic replica distribution reducing the reliability weaknesses ; a replica allocation algorithm making the highly accessed elements to be replicated in more server nodes than the lowly accessed elements; a dynamic content replication strategy which allows to determine when content redistribution is needed and how this redistribution must be performed; the adaptation of three request dispatching policies to the case of partial content replication: round robin dispatching, less loaded node dispatching and locality aware request distribution dispatching (LARD). Evaluations have proved that the reliability of a cluster based Web system is limited by its Web switch reliability. In the same way, this thesis shows that a partial replication based system using a relatively low number of replicas offers an equivalent reliability to that of a system based on full replication, while its storage capacity is much higher. Besides, partial replication does not affect in a negative way to the global system performanc

Static partitioning and mapping of kernel-based applications over modern heterogeneous architectures

Heterogeneous Architectures Are Being Used Extensively To Improve System Processing Capabilities. Critical Functions Of Each Application (Kernels) Can Be Mapped To Different Computing Devices (I.E. Cpus, Gpgpus, Accelerators) To Maximize Performance. However, Best Performance Can Only Be Achieved If Kernels Are Accurately Mapped To The Right Device. Moreover, In Some Cases Those Kernels Could Be Split And Executed Over Several Devices At The Same Time To Maximize The Use Of Compute Resources On Heterogeneous Parallel Architectures. In This Paper, We Define A Static Partitioning Model Based On Profiling Information From Previous Executions. This Model Follows A Quantitative Model Approach Which Computes The Optimal Match According To User-Defined Constraints. We Test Different Scenarios To Evaluate Our Model: Single Kernel And Multi-Kernel Applications. Experimental Results Show That Our Static Partitioning Model Could Increase Performance Of Parallel Applications By Deploying Not Only Different Kernels Over Different Devices But A Single Kernel Over Multiple Devices. This Allows To Avoid Having Idle Compute Resources On Heterogeneous Platforms, As Well As Enhancing The Overall Performance. (C) 2015 Elsevier B.V. All Rights Reserved.The research leading to these results has received funding from the European Union Seventh Framework Programme (FP7/2007–2013) under grant agreement n. 609666 [24]

Computational approach to extend the air-conditioning usage to adaptive comfort: Adaptive-Comfort-Control-Implementation Script

Recently, the energy saving potential from using setpoint temperatures based on adaptive comfort has been studied. This study proposes a computational approach, the Adaptive-Comfort-Control-Implementation Script (ACCIS), to extend the air-conditioning usage to adaptive comfort. ACCIS transforms PMV-based into adaptive setpoint building energy models according to both an Input Data File (IDF) and the setup specified by the user. Originally, ACCIS was an Energy Management System (EMS) script, but available functions have been extended, and ACCIS has been nested in an ease-to-use Python package called Adaptive Comfort Control Implemented Model (“accim”). A case study has been tested, whose results showed that adaptive setpoint temperatures could achieve an 83% of energy savings. However, its most powerful attribute is that it allows many simulations to be run with no limit because of both its high customisation properties and the fact that it allows the same IDF to be run with various EPW files

Potential of applying adaptive strategies in buildings to reduce the severity of fuel poverty according to the climate zone and climate change: The case of Andalusia

The reduction of fuel poverty is among the major challenges of countries, policymakers, stakeholders, and researchers. Many contributions have today emerged; however, two aspects should be widely considered. On the one hand, the use of strategies based on the reduction of energy consumption through the adaptive approach, and on the other hand, the impact of climate change on fuel poverty, particularly considering the recent representative concentration pathways (RCP). This paper addresses both issues in Andalusia, which is among the regions with the highest population ratio under poverty risk. For this purpose, 4 zones with possibilities of applying adaptive strategies were distinguished in the Andalusian geography, and 3 climate change scenarios (RCP 2.6, RCP 4.5, and RCP 8.5) were projected in each decade (from 2030 to 2100). A total of 6,528 cases of representative social housing, simulated in all scenarios, were parametrically studied. All data were assessed from the point of view of fuel poverty risk. The results showed that the adaptive strategies influence the reduction of fuel poverty, both in annual and monthly values. Moreover, the increase in fuel poverty cases because of global warming could be reduced by this approach in the four zones detected in Andalusia

Incremento de prestaciones en el acceso en Grid de datos

Ponencias de las Decimosextas Jornadas de Paralelismo celebradas del 13 al 16 de septiembre de 2005 en GranadaEl modelo de computación Grid ha evolucionado en los últimos años para proporcionar un entorno de computación de altas prestaciones en redes de área amplia. Sin embargo, uno de los mayores problemas se encuentra en las aplicaciones que hacen uso intensivo y masivo de datos. Como solución a los problemas de estas aplicaciones se ha utilizado la replicación. Sin embargo, la replicación clásica adolece de ciertos problemas como la adaptabilidad y la alta latencia del nuevo entorno. Por ello se propone un nuevo algoritmo de replicación y organización de datos que proporciona un acceso de altas prestaciones en un Data Grid.Publicad