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Future exascale systems, formed by millions of cores, will present high failure rates, and long-running applications will need to make use of new fault tolerance techniques to ensure the successful execution completion. The Fault Tolerance Working Group, within the MPI forum, has presented the ULFM (User Level Failure Mitigation) proposal, providing new functionalities for the implementation of resilient MPI applications. In this work, the CPPC checkpointing framework is extended to exploit the new ULFM functionalities. The proposed solution transparently obtains resilient MPI applications by instrumenting the original application code. Besides, a multithreaded multilevel checkpointing, in which the checkpoint files are saved in different memory levels, improves the scalability of the solution. The experimental evaluation shows a low overhead when tolerating failures in one or several MPI processes.

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The growth in the number of computational resources used by high-performance computing (HPC) systems leads to an increase in failure rates. Fault-tolerant techniques will become essential for long-running applications executing in future exascale systems, not only to ensure the completion of their execution in these systems but also to improve their energy consumption. Although the Message Passing Interface (MPI) is the most popular programming model for distributed-memory HPC systems, as of now, it does not provide any fault-tolerant construct for users to handle failures. Thus, the recovery procedure is postponed until the application is aborted and re-spawned. The proposal of the User Level Failure Mitigation (ULFM) interface in the MPI forum provides new opportunities in this field, enabling the implementation of resilient MPI applications, system runtimes, and programming language constructs able to detect and react to failures without aborting their execution. This paper presents a global overview of the resilience interfaces provided by the ULFM specification, covers archetypal usage patterns and building blocks, and surveys the wide variety of application-driven solutions that have exploited them in recent years. The large and varied number of approaches in the literature proves that ULFM provides the necessary flexibility to implement efficient faulttolerant MPI applications. All the proposed solutions are based on application-driven recovery mechanisms, which allows reducing the overhead and obtaining the required level of efficiency needed in the future exascale platforms.

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The MPI (Message Passing Interface) standard is the most popular parallel programming model for distributed systems. However, it lacks fault tolerance support and, traditionally, failures are addressed with stopand-restart checkpointing solutions. The proposal of ULFM (User Level Failure Mitigation) for the inclusion of resilience capabilities in the MPI standard provides new opportunities in this field, allowing the implementation of resilient MPI applications, i.e. applications that are able to detect and react to failures without stopping their execution. This work compares the performance of a traditional stop-and-restart checkpointing solution with its equivalent resilience proposal. Both approaches are built on top of CPPC (ComPiler for Portable Checkpoiting), an application-level checkpointing tool for MPI applications, and they allow to transparently obtain fault-tolerant MPI applications from generic MPI SPMD (Single Program Multiple Data) programs. The evaluation is focussed on the scalability of the two solutions, comparing both proposals using up to 3072 cores.

RESUMEN:Introducción. El aprendizaje a lo largo de la vida (ALV) es un aprendizaje intencional que involucra a las personas a lo largo de su vida para su desarrollo personal y profesional y para mejorar la calidad de su vida. Desarrollar la capacidad para el ALV durante la Educación Superior es importante para facilitar la incorporación de los nuevos graduados al mundo laboral. Con esta finalidad, hemos diseñado un programa sobre 'Competencias para el aprendizaje a lo largo de la vida para estudiantes de Educación superior', que hemos aplicado a estudiantes de grado de la Universidad de San Diego (USD), California, USA y a los de la Universidad Nacional de Educación a Distancia de Madrid (España). Metodología empleada. Presentamos el programa mediante un taller donde el debate y la reflexión jugaron un papel importante. Para comprobar los logros del programa, hemos utilizado metodologías mixtas, propias de la investigación evaluativa. Aplicamos un cuestionario y, una práctica y el análisis de los portafolios personales de los estudiantes, hemos valorado la eficacia, satisfacción e impacto del programa. Resultados. La comparación de las respuestas dadas por los estudiantes antes y después de la presentación del programa indica que los estudiantes mejoraron su información sobre el ALV y las competencias clave para su desarrollo profesional. Discusión. El programa contribuye a la mejora en competencias y compromiso con el aprendizaje de los estudiantes a lo largo de la vida.PALABRAS CLAVE: Desarrollo de competencias claves; educación superior; programa para el aprendizaje a lo largo de la vida; cuestionario sobre el aprendizaje a lo largo de la vida.ABSTRACT: Introduction. Lifelong learning (LLL) is an intentional learning that people engage in th- Pedagogía Social. Revista Interuniversitaria, 2013, 22, pp. 137-151 http://www.