Virtual-physical registers

A novel dynamic register renaming approach is proposed in this work. The key idea of the novel scheme is to delay the allocation of physical registers until a late stage in the pipeline, instead of doing it in the decode stage as conventional schemes do. In this way, the register pressure is reduced and the processor can exploit more instruction-level parallelism. Delaying the allocation of physical registers require some additional artifact to keep track of dependences. This is achieved by introducing the concept of virtual-physical registers, which do not require any storage location and are used to identify dependences among instructions that have not yet allocated a register to its destination operand. Two alternative allocation strategies have been investigated that differ in the stage where physical registers are allocated: issue or write-back. The experimental evaluation has confirmed the higher performance of the latter alternative. We have performed all evaluation of the novel scheme through a detailed simulation of a dynamically scheduled processor. The results show a significant improvement (e.g., 19% increase in IPC for a machine with 64 physical registers in each file) when compared with the traditional register renaming approach.Peer ReviewedPostprint (published version

Spanish reality perception in immigrant’s collective imaginary

¿Cuál es la percepción de España que tienen, previamente a su llegada, los inmigrantes? En este artículo se analiza el imaginario de las comunidades con mayor presencia en el país, así como las nuevas ideas conformadas a raíz de la experiencia con la realidad española, a partir del análisis del papel desempeñado por los medios de comunicación.Which is the perception of Spain that immigrants have before they arrive to Spain? In this article we analyze the imaginary group of the communities with greater presence in the country, as well as the new ideas conformed as a result of the experience in the Spanish everyday reality, considering the roll of mass media

About the freedom of the press in Italy. Berlusconi’s conflict of interests and his influence on the democracy of the ‘Bel Paese’

La libertad de prensa en Italia se encuentra en una peculiar situación derivada del conflicto de intereses concentrados en la persona de su primer ministro, Silvio Berlusconi, de las presiones que ejercen los clanes mafiosos y del escaso pluralismo informativo como resultado de una fuerte concentración mediática. Este artículo analiza el estado de salud de la democracia italiana y las dificultades y bondades del ejercicio del periodismo. A través de entrevistas en profundidad a los corresponsales Miguel Mora (El País), Irene Hernández (El Mundo), Gloria Moreno (Europa Press), Juan Lara (Efe), Antonio Pelayo (Antena 3) y Paloma Gómez Borrero (Cope), se intenta reflejar cómo es el desempeño de la labor periodística desde la óptica de los profesionales españoles afincados en Roma. Sus testimonios se enriquecen con los de periodistas de la agencia Ansa y de la Rai.Freedom of the press in Italy is in a peculiar situation resulting from a conflict of interests concentrated on the person of his Premier, Silvio Berlusconi, the pressures exerted by mafia clans and the limited pluralism as a result of a strong media concentration. This article analyzes the health of Italian democracy and difficulties and benefits of the practice of journalism. Through deep interviews to correspondents Miguel Mora (El País), Irene Hernández (El Mundo), Gloria Moreno (Europa Press), Juan Lara (Efe), Antonio Pelayo (Antena 3) and Paloma Gómez Borrero (Cope) the article tries to reflect what means being a journalist in Italy from the perspective of Spanish professionals settled in Rome. It also includes opinions of journalists of the agency Ansa and Rai

Late allocation and early release of physical registers

The register file is one of the critical components of current processors in terms of access time and power consumption. Among other things, the potential to exploit instruction-level parallelism is closely related to the size and number of ports of the register file. In conventional register renaming schemes, both register allocation and releasing are conservatively done, the former at the rename stage, before registers are loaded with values, and the latter at the commit stage of the instruction redefining the same register, once registers are not used any more. We introduce VP-LAER, a renaming scheme that allocates registers later and releases them earlier than conventional schemes. Specifically, physical registers are allocated at the end of the execution stage and released as soon as the processor realizes that there will be no further use of them. VP-LAER enhances register utilization, that is, the fraction of allocated registers having a value to be read in the future. Detailed cycle-level simulations show either a significant speedup for a given register file size or a reduction in the register file size for a given performance level, especially for floating-point codes, where the register file pressure is usually high.Peer ReviewedPostprint (published version

Static locality analysis for cache management

Most memory references in numerical codes correspond to array references whose indices are affine functions of surrounding loop indices. These array references follow a regular predictable memory pattern that can be analysed at compile time. This analysis can provide valuable information like the locality exhibited by the program, which can be used to implement more intelligent caching strategy. In this paper we propose a static locality analysis oriented to the management of data caches. We show that previous proposals on locality analysis are not appropriate when the proposals have a high conflict miss ratio. This paper examines those proposals by introducing a compile-time interference analysis that significantly improve the performance of them. We first show how this analysis can be used to characterize the dynamic locality properties of numerical codes. This evaluation show for instance that a large percentage of references exhibit any type of locality. This motivates the use of a dual data cache, which has a module specialized to exploit temporal locality, and a selective cache respectively. Then, the performance provided by these two cache organizations is evaluated. In both organizations, the static locality analysis is responsible for tagging each memory instruction accordingly to the particular type(s) of locality that it exhibits.Peer ReviewedPostprint (published version

Empleo y usos de Internet en las comunidades inmigradas. La red como herramienta neutralizadora de la distancia

Las dinámicas migratorias se configuran hoy de forma diferente a aquéllas que durante siglos han escrito la historia de la humanidad. Las nuevas tecnologías, con gran penetración en las sociedades altamente industrializadas, cobran un auge creciente y nos obligan a pensar el significado que ostentan para las comunidades inmigradas así como a redefinir los actuales proyectos migratorios. Internet y sus posibilidades como herramienta neutralizadora de las distancias permiten al inmigrante contemporáneo sentirse, más que nunca antes, próximo a su cultura y comunidad de origen. El correo electrónico, la mensajería instantánea, con la transmisión de imágenes y sonido en directo, la posibilidad de leer los periódicos on line de la comunidad de pertenencia, etcétera, dan muestra de cómo las distancias se acortan en un mundo atravesado de lleno por los procesos de globalización. Junto a la Red, otras tecnologías como el cable y el satélite permiten a estas comunidades ver sus canales de televisión y acceder, así, a contenidos en su idioma. En la comunicación se analiza el consumo mediático y tecnológico que hacen las comunidades de inmigrantes en las sociedades de destino, así como las motivaciones que orientan este consumo. Los resultados han sido extraídos de un trabajo de campo antropológico realizado con una muestra de 40 inmigrantes de diversas nacionalidades residentes en el sur de España. En el presente trabajo se exponen las conclusiones más significativas apoyadas con declaraciones extraídas de entrevistas en profundidad. El empleo de Internet con diferentes finalidades muestra cotas altas en los casos seleccionados. No en vano, la tasa de uso de la Red es más elevada entre los residentes extranjeros que en el caso de los españoles. En resumen en los objetivos de la comunicación se plantean como cuestiones clave: • El uso mediático de los inmigrantes en España y el consumo de medios de origen, posibilitado por las nuevas tecnologías de la información, para el mantenimiento y reproducción de sus rasgos culturales identitarios. • El empleo de Internet como herramienta de interrelación social, neutralizadora de las distancias

Hardware schemes for early register release

Register files are becoming one of the critical components of current out-of-order processors in terms of delay and power consumption, since their potential to exploit instruction-level parallelism is quite related to the size and number of ports of the register file. In conventional register renaming schemes, register releasing is conservatively done only after the instruction that redefines the same register is committed. Instead, we propose a scheme that releases registers as soon as the processor knows that there will be no further use of them. We present two early releasing hardware implementations with different performance/complexity trade-offs. Detailed cycle-level simulations show either a significant speedup for a given register file size, or a reduction in register file size for a given performance level.Peer ReviewedPostprint (published version

Ecologies of learning, visual narratives and ethnography. Metholodogical notes about Universidad Rural Paulo Freire case.

In this paper we present some of the first methodological results of the R&D Project called "Ecologies of learning in multiple contexts: analysis of expanded education projects and citizenship configurations" funded by Minister of Economy and Competitiveness (Spain) . The interest of this project arises after considering that much of the individual and organizational learnings have been turning invisible in the different educational spaces. Therefore, our purpose is to study the different socio-educational mechanisms that individuals and organizations put into play in differents scenarios: schools, asociations, virtual academical contexts, etc. On this ocassion, we present some of the methodological aspects from a rural environment, especifically the study we are developing with ‘Universidad Rural Paulo Freire’ of the Ronda mountain range (onwards URPF). This organization is focused in the recovery of tradicional learnings that people used to have around the rural world. At the same time, they are settled in a critical perspective that connects their actions with approaches of sustainability, dignity, feminims, etc. The general objetives we consider for this project are the following: 1) To know life style of people in Ronda mountain range context. 2) To understand the configuration of URPF group and its impact in the territory. 3) To promote learning communities of practice with other organizations. In order to draw on these general porpuses and after an agreement process with the URPF collective, we designed methodologically the develop of life stories, visual narratives and a deep narrative ethnography.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Hypernode reduction modulo scheduling

Software pipelining is a loop scheduling technique that extracts parallelism from loops by overlapping the execution of several consecutive iterations. Most prior scheduling research has focused on achieving minimum execution time, without regarding register requirements. Most strategies tend to stretch operand lifetimes because they schedule some operations too early or too late. The paper presents a novel strategy that simultaneously schedules some operations late and other operations early, minimizing all the stretchable dependencies and therefore reducing the registers required by the loop. The key of this strategy is a pre-ordering that selects the order in which the operations will be scheduled. The results show that the method described in this paper performs better than other heuristic methods and almost as well as a linear programming method but requiring much less time to produce the schedules.Peer ReviewedPostprint (published version

Swing modulo scheduling: a lifetime-sensitive approach

This paper presents a novel software pipelining approach, which is called Swing Modulo Scheduling (SMS). It generates schedules that are near optimal in terms of initiation interval, register requirements and stage count. Swing Modulo Scheduling is an heuristic approach that has a low computational cost. The paper describes the technique and evaluates it for the Perfect Club benchmark suite. SMS is compared with other heuristic methods showing that it outperforms them in terms of the quality of the obtained schedules and compilation time. SMS is also compared with an integer linear programming approach that generates optimum schedules but with a huge computational cost, which makes it feasible only for very small loops. For a set of small loops, SMS obtained the optimum initiation interval in all the cases and its schedules required only 5% more registers and a 1% higher stage count than the optimumPeer ReviewedPostprint (published version