Loop pipelining with resource and timing constraints

Developing efficient programs for many of the current parallel computers is not easy due to the architectural complexity of those machines. The wide variety of machine organizations often makes it more difficult to port an existing program than to reprogram it completely. Therefore, powerful translators are necessary to generate effective code and free the programmer from concerns about the specific characteristics of the target machine. This work focuses on techniques to be used by an important class of translators, whose objective is to transform sequential programs into equivalent more parallel programs. The transformations are performed at instruction level in order to exploit low level parallelism and increase memory locality.Most of the current applications are programmed in languages which do not allow us to express parallelism between high-level sentences (as Pascal, C or Fortran). Furthermore, a lot of applications written ten or more years ago are still used today, and it is not feasible to rewrite such applications for many reasons (not only technical reasons, but also economic ones). Translators enable programmers to write the application in a familiar sequential programming language, without concerning their selves with the architecture of the target machine. Current compilers for parallel architectures not only translate a program written on a high-level language to the appropriate machine language, but also perform some transformations in the final code in order to execute the program in a more parallel way. The transformations improve the performance in the execution of the program by making use of the knowledge that the compiler has about the machine architecture. The semantics of the program remain intact after any transformation.Experiments show that limiting parallelization to basic blocks not included in loops limits maximum speedup. This is because loops often comprise a large portion of the parallelism available to be exploited in a program. For this reason, a lot of effort has been devoted in the recent years to parallelize loop execution. Several parallel computer architectures and compilation techniques have been proposed to exploit such a parallelism at different granularities. Multiprocessors exploit coarse grained parallelism by distributing entire loop iterations to different processors. Systems oriented to the high-level synthesis (HLS) of VLSI circuits, superscalar processors and very long instruction word (VLIW) processors exploit fine-grained parallelism at instruction level. This work addresses fine-grained parallelization of loops addressed to the HLS of VLSI circuits. Two algorithms are proposed for resource constraints and for timing constraints. An algorithm to reduce the number of registers required to execute a loop in a given architecture is also proposed.Postprint (published version

Implantació de les competències transversals al Grau en Enginyeria Informàtica a la FIB

Peer Reviewe

Las mentiras del EEES

En este artículo se presenta el punto de vista del autor sobre cómo se han implantado los planes de estudio del EEES en España y algunas de las cosas que, en su opinión, no se han hecho bien. El EEES despertó muchas expectativas en una parte considerable del profesorado. En teoría traería consigo muchas mejoras en los métodos de enseñanza-aprendizaje, y contribuiría a aumentar la movilidad y mejorar la empleabilidad de los egresados. Dieciocho años después de la declaración de Bolonia, y siete años después de la implantación del EEES en España, algunas de esas expectativas no se han cumplido: (1) Los precios de los másteres son mayores que los de los grados, que ni siquiera son los mismos en todas las comunidades autónomas; (2) muchos planes de estudios no están basados en competencias; (3) los métodos de aprendizaje activo no son todavía utilizados con asiduidad y la clase magistral sigue siendo la metodología más común; (4) la evaluación continua no es la forma de evaluación predominante y a menudo es confundida con la examinación continua y (5) el esperado aumento de la movilidad y la empleabilidad no se ha conseguido en la mayoría de países de Europa.This paper presents the author's point of view on how the curricula of the EHEA have been implemented in Spain and some of the things that, in his opinion, have not been done well. The EHEA aroused many expectations in a considerable part of the teaching staff. In theory it would bring many improvements in teaching-learning methods, and would contribute to increase mobility and improve the employability of graduates. Eighteen years after the declaration of Bologna, and seven years after the introduction of the EHEA in Spain, some of those expectations have not been met: (1) The prices of the master degrees are higher than those of the bachelor degrees, which are not even the same in all the autonomous communities; (2) many curricula are not competency-based; (3) active learning methods are still not used regularly and the master class remains the most common methodology; (4) continuous assessment is not the predominant form of evaluation and is often confused with continuous examination, and (5) the expected increase in mobility and employability has not been achieved in most European countries.Peer ReviewedPostprint (published version

Evidencias para acreditar una titulación de grado

Las titulaciones de grado y postgrado deben ser acreditadas seis y cuatro años después de su puesta en marcha, respectivamente. Algunas van a someterse al proceso de acreditación a mediados de 2014. Para conseguir la acreditación, las titulaciones tendrán que presentar evidencias de que los estudiantes han adquirido las competencias de la titulación, y de cómo lo han hecho. Estas evidencias tendrán que ser a menudo cualitativas, y si el centro no dispone de un sistema para obtenerlas de forma automática, su elaboración puede suponer un enorme esfuerzo. En este trabajo se describen el tipo de evidencias que se pueden presentar para acreditar una titulación y se presenta una estrategia para la generación sencilla y eficiente de las mismas.SUMMARY -- Graduate and undergraduate degrees must be accredited six and four years after their launch. Some degrees will undergo the accreditation process in mid- 2014. To get accreditation, degrees must present evidences that students have acquired the skills of the degree, and how they have done it. These evidences will often be qualitative, and if the center does not have a system to obtain them in an automatic way, processing them can become a huge effort. In this work, the kind of evidence that can be presented to accredit a degree is defined and a strategy for simple and efficient generation of these evidences is presented

The EDINSOST project: improving sustainability education in spanish higher education

The EDINSOST R+D+i “Society Challenges” Project, funded by the Spanish Ministry of Economy and Competitiveness and the Spanish Ministry of Science, Innovation and Universities under the research challenge in the field of social change and innovation, aims to contribute to the improvement of social challenges across the (1) Spanish Strategy for Science, Technology and Innovation, (2) the State Plan of Scientific and Technical Research and Innovation, and (3) the European 2020 Strategy. The research is both highly multidisciplinary and contextualized and is applied in Ten Spanish Universities working together in the “Curriculum sustainability" group of the CRUE Sectorial Commission of Sustainability. The goal of this group is to create synergies and action frameworks agreed at a national level. This is an area of research action whose lack of common criteria for integrating sustainability competencies, learning processes and assessment hinders their achievement. To meet this challenge, frameworks and processes have been designed to facilitate the integration of sustainability into the university curriculum holistically through mapping and validation of pedagogical practices and the diagnosis of the state of Spanish universities, for which building materials for teaching and learning sustainability competencies have been developed. The project objectives and results are focused on: 1) Defining the map of sustainability competencies of the university degrees involved in the project, and establishing the framework to facilitate their integration in a holistic manner; 2) validating teaching strategies for the acquisition of sustainability competencies from a constructivist and community-oriented pedagogical approach; 3) diagnosing the state of faculty sustainability training needs and developing and pilot training proposals; and 4) diagnosing the state of learning of sustainability competencies in university students as well as preparing and piloting training proposals. The research methodology has an interpretive focus and uses quantitative and qualitative techniques to cover a population with three impact levels. Firstly, Bachelor and Master Degrees that integrate the three pillars of sustainability (environmental, social and economic). Secondly, and taking into account their long-term multiplier effect, special emphasis is made on five Bachelor and Master degrees in Education, since these graduates are the future teachers of the next generation of citizens. Finally, seven technological Bachelor Degrees are studied for their great impact on societal challenges.Peer ReviewedPostprint (published version

Time-constrained loop pipelining

This paper addresses the problem of Time-Constrained Loop Pipelining, i.e. given a fixed throughput, finding a schedule of a loop which minimizes resource requirements. We propose a methodology, called TCLP, based on dividing the problem into two simpler and independent tasks: retiming and scheduling. TCLP explores different sets of resources, searching for a maximum resource utilization. This reduces area requirements. After a minimum set of resources has been found, the execution throughput is increased and the number of registers required by the loop schedule is reduced. TCLP attempts to generate a schedule which minimizes cost in time and area (resources and registers). The results show that TCLP obtains optimal schedules in most cases.Peer ReviewedPostprint (published version

A mathematical formulation of the loop pipelining problem

This paper presents a mathematical model for the loop pipelining problem that considers several parameters for optimization and supports any combination of resource and timing constraints. The unrolling degree of the loop is one of the variables explored by the model. By using Farey’s series, an optimal exploration of the unrolling degree is performed and optimal solutions not considered by other methods are obtained. Finding an optimal schedule that minimizes resource and register requirements is solved by using an Integer linear programming (ILP) model. A novel paradigm called branch and prune is proposed to eficiently converge towards the optimal schedule and prune the search tree for integer solutions, thus drastically reducing the running time. This is the first formulation that combines the unrolling degree of the loop with timing and resource constraints in a mathematical model that guarantees optimal solutions.Peer ReviewedPostprint (author's final draft

Cómo impartir una clase magistral según la neurociencia

Las clases magistrales han sido una de las técnicas fundamentales de enseñanza desde tiempos de la civilización griega, y probablemente incluso desde mucho antes. Una clase magistral es una actividad centrada en el profesor, en la que el estudiante es un agente pasivo que “recibe” las explicaciones del agente transmisor, que en teoría es un amplio conocedor del tema estudiado. Como agente pasivo que es, el estudiante aprende en una clase magistral en función del interés que tenga en el tema que se trata. En este artículo se aborda el aprendizaje desde la perspectiva de estudiar sus tres fases principales (motivación, atención, memorización), y cómo cada una de estas fases debe abordarse en una clase magistral. Para realizar este análisis se usan los conocimientos actuales desde la perspectiva de la neurociencia, de forma que en el artículo se proporcionan un conjunto de recomendaciones sobre cómo debe hacerse una clase magistral teniendo en cuenta el funcionamiento del cerebro humano.Master classes have been one of the fundamental teaching techniques since Greek civilization times, and probably even from much earlier. A master class is an activity focused on the teacher, in which the student is a passive agent who "receives" explanations from the transmitting agent, who in theory is a broad expert on the studied subject. As a passive agent, the student learns in a master class according to the interest he/she has in the subject. In this paper, learning is approached from the perspective of studying its three main phases (motivation, attention, and memorization) and how each of these phases should be addressed in a master class form neuroscience’s perspective. The knowledge of current neuroscience is used to perform this analysis, so that the paper provides a set of recommendations on how a master class should be given considering the functioning of the human brain.Peer ReviewedPostprint (published version

Características deseables en un procesador pedagógico para la enseñanza básica de Arquitectura de Computadores

En este artículo se analiza cómo debería ser la arquitectura a nivel de lenguaje máquina de un procesador pedagógico que se estudie en una asignatura de primeros cursos de una Ingeniería Informática, ya sea técnica o superior. Se estudian también las características básicas de un lenguaje ensamblador y de un simulador para dicho procesador. Finalmente, se presentan tres ejemplos de procesador pedagógico que se usan o se han usado en universidades españolas y se discuten sus ventajas e inconvenientes.Este trabajo ha sido financiado por el Ministerio de Educación y Ciencia mediante el contrato TIC 98-0410

¿Cómo serán las asignaturas del EEES?

En este artículo se reflexiona sobre cómo serán las asignaturas de los estudios universitarios en España en el Espacio Europeo de Educación Superior (EEES) y cuáles serán las principales diferencias respecto a las actuales asignaturas. El artículo presenta los actuales modelos de aprendizaje y los compara con el del futuro EEES. El cambio de paradigma educativo -pasar de las enseñanzas del profesor al aprendizaje del alumno- dirigirá el cambio, y los créditos ECTS serán la forma de implementarlo. Se presenta un ejemplo de adaptación de una asignatura actual al EEES, y se concluye que el modelo de aprendizaje más usado en la actualidad -el basado en clases de teoría, problemas y laboratorio- no será válido para el EEES.La elaboración de este trabajo ha sido financiada en parte por la CICYT TIC2001-0995-C02-01, y su presentación por la Facultat d’Informática de Barcelona y el Departament d’Arquitectura de Computadors de la UPC