Cómo evaluar continua e individualmente en asignaturas basadas en proyectos

En este artículo se describe el diseño de la asignatura de Projecte de Xarxes de Computadors i Sistemes Operatius (PXCSO) [1] de la Facultat d'Informàtica de Barcelona (FIB) [2], de la Universitat Politècnica de Catalunya (UPC) [3]. Una asignatura de proyectos, que tiene por objetivo dotar a los alumnos de ingeniería informática de un conjunto de competencias tanto técnicas como no técnicas. La asignatura está diseñada entorno a la ejecución de un proyecto informático, en el que los alumnos trabajan en grupos de 8. Se ha implantado un sistema de evaluación continua e individualizada, que permite que, tanto el profesor como el alumno, tengan una percepción del rendimiento del trabajo individual, proporcionando una realimentación que sirva de estímulo a los estudiantes dentro de cada grupo. Este modelo constituye la experiencia previa más similar al mercado laboral.Peer Reviewe

On-Chip memories, the OS perspective

This paper is a work in progress study of the operating system services required to manage on-chip memories. We are evaluating different CMP on-chip memories configurations. Chip-MultiProcessors (CMP) architectures integrating multiple computing and memory elements presents different problems (coherency, latency, ...) that must be solved. On-chip local memories are directly addressable and their latency is much shorter than off-chip main memories. Since memory latency is a key factor for application performance, we study how the OS can help.Postprint (author’s final draft

Adaptive runtime-assisted block prefetching on chip-multiprocessors

Memory stalls are a significant source of performance degradation in modern processors. Data prefetching is a widely adopted and well studied technique used to alleviate this problem. Prefetching can be performed by the hardware, or be initiated and controlled by software. Among software controlled prefetching we find a wide variety of schemes, including runtime-directed prefetching and more specifically runtime-directed block prefetching. This paper proposes a hybrid prefetching mechanism that integrates a software driven block prefetcher with existing hardware prefetching techniques. Our runtime-assisted software prefetcher brings large blocks of data on-chip with the support of a low cost hardware engine, and synergizes with existing hardware prefetchers that manage locality at a finer granularity. The runtime system that drives the prefetch engine dynamically selects which cache to prefetch to. Our evaluation on a set of scientific benchmarks obtains a maximum speed up of 32 and 10 % on average compared to a baseline with hardware prefetching only. As a result, we also achieve a reduction of up to 18 and 3 % on average in energy-to-solution.Peer ReviewedPostprint (author's final draft

Cómo evaluar continua e individualmente en asignaturas basadas en proyectos

En este artículo se describe el diseño de la asignatura de Projecte de Xarxes de Computadors i Sistemes Operatius (PXCSO) [1] de la Facultat d'Informàtica de Barcelona (FIB) [2], de la Universitat Politècnica de Catalunya (UPC) [3]. Una asignatura de proyectos, que tiene por objetivo dotar a los alumnos de ingeniería informática de un conjunto de competencias tanto técnicas como no técnicas. La asignatura está diseñada entorno a la ejecución de un proyecto informático, en el que los alumnos trabajan en grupos de 8. Se ha implantado un sistema de evaluación continua e individualizada, que permite que, tanto el profesor como el alumno, tengan una percepción del rendimiento del trabajo individual, proporcionando una realimentación que sirva de estímulo a los estudiantes dentro de cada grupo. Este modelo constituye la experiencia previa más similar al mercado laboral.Peer Reviewe

On-Chip memories, the OS perspective

This paper is a work in progress study of the operating system services required to manage on-chip memories. We are evaluating different CMP on-chip memories configurations. Chip-MultiProcessors (CMP) architectures integrating multiple computing and memory elements presents different problems (coherency, latency, ...) that must be solved. On-chip local memories are directly addressable and their latency is much shorter than off-chip main memories. Since memory latency is a key factor for application performance, we study how the OS can help

On-Chip memories, the OS perspective

This paper is a work in progress study of the operating system services required to manage on-chip memories. We are evaluating different CMP on-chip memories configurations. Chip-MultiProcessors (CMP) architectures integrating multiple computing and memory elements presents different problems (coherency, latency, ...) that must be solved. On-chip local memories are directly addressable and their latency is much shorter than off-chip main memories. Since memory latency is a key factor for application performance, we study how the OS can help

Adaptive runtime-assisted block prefetching on chip-multiprocessors

Memory stalls are a significant source of performance degradation in modern processors. Data prefetching is a widely adopted and well studied technique used to alleviate this problem. Prefetching can be performed by the hardware, or be initiated and controlled by software. Among software controlled prefetching we find a wide variety of schemes, including runtime-directed prefetching and more specifically runtime-directed block prefetching. This paper proposes a hybrid prefetching mechanism that integrates a software driven block prefetcher with existing hardware prefetching techniques. Our runtime-assisted software prefetcher brings large blocks of data on-chip with the support of a low cost hardware engine, and synergizes with existing hardware prefetchers that manage locality at a finer granularity. The runtime system that drives the prefetch engine dynamically selects which cache to prefetch to. Our evaluation on a set of scientific benchmarks obtains a maximum speed up of 32 and 10 % on average compared to a baseline with hardware prefetching only. As a result, we also achieve a reduction of up to 18 and 3 % on average in energy-to-solution.Peer Reviewe

On the simulation of large-scale architectures using multiple application abstraction levels

Simulation is a key tool for computer architecture research. In particular, cycle-accurate simulators are extremely important for microarchitecture exploration and detailed design decisions, but they are slow and, so, not suitable for simulating large-scale architectures, nor are theymeant for this. Moreover,microarchitecture design decisions are irrelevant, or even misleading, for early processor design stages and high-level explorations. This allows one to raise the abstraction level of the simulated architecture, and also the application abstraction level, as it does not necessarily have to be represented as an instruction stream. In this paper we introduce a definition of different application abstraction levels, and how these are employed in TaskSim, a multi-core architecture simulator, to provide several architecture modeling abstractions, and simulate large-scale architectures with hundreds of cores. We compare the simulation speed of these abstraction levels to the ones in existing simulation tools, and also evaluate their utility and accuracy. Our simulations show that a very high-level abstraction, which may be even faster than native execution, is useful for scalability studies on parallel applications; and that just simulating explicit memory transfers, we achieve accurate simulations for architectures using non-coherent scratchpad memories, with just a 25xslowdown compared to native execution. Furthermore, we revisit trace memory simulation techniques, that are more abstract than instruction-by-instruction simulations and provide an 18x simulation speedup.Peer Reviewe

On the simulation of large-scale architectures using multiple application abstraction levels

Simulation is a key tool for computer architecture research. In particular, cycle-accurate simulators are extremely important for microarchitecture exploration and detailed design decisions, but they are slow and, so, not suitable for simulating large-scale architectures, nor are theymeant for this. Moreover,microarchitecture design decisions are irrelevant, or even misleading, for early processor design stages and high-level explorations. This allows one to raise the abstraction level of the simulated architecture, and also the application abstraction level, as it does not necessarily have to be represented as an instruction stream. In this paper we introduce a definition of different application abstraction levels, and how these are employed in TaskSim, a multi-core architecture simulator, to provide several architecture modeling abstractions, and simulate large-scale architectures with hundreds of cores. We compare the simulation speed of these abstraction levels to the ones in existing simulation tools, and also evaluate their utility and accuracy. Our simulations show that a very high-level abstraction, which may be even faster than native execution, is useful for scalability studies on parallel applications; and that just simulating explicit memory transfers, we achieve accurate simulations for architectures using non-coherent scratchpad memories, with just a 25xslowdown compared to native execution. Furthermore, we revisit trace memory simulation techniques, that are more abstract than instruction-by-instruction simulations and provide an 18x simulation speedup.Peer ReviewedPostprint (published version

On the simulation of large-scale architectures using multiple application abstraction levels

Simulation is a key tool for computer architecture research. In particular, cycle-accurate simulators are extremely important for microarchitecture exploration and detailed design decisions, but they are slow and, so, not suitable for simulating large-scale architectures, nor are theymeant for this. Moreover,microarchitecture design decisions are irrelevant, or even misleading, for early processor design stages and high-level explorations. This allows one to raise the abstraction level of the simulated architecture, and also the application abstraction level, as it does not necessarily have to be represented as an instruction stream. In this paper we introduce a definition of different application abstraction levels, and how these are employed in TaskSim, a multi-core architecture simulator, to provide several architecture modeling abstractions, and simulate large-scale architectures with hundreds of cores. We compare the simulation speed of these abstraction levels to the ones in existing simulation tools, and also evaluate their utility and accuracy. Our simulations show that a very high-level abstraction, which may be even faster than native execution, is useful for scalability studies on parallel applications; and that just simulating explicit memory transfers, we achieve accurate simulations for architectures using non-coherent scratchpad memories, with just a 25xslowdown compared to native execution. Furthermore, we revisit trace memory simulation techniques, that are more abstract than instruction-by-instruction simulations and provide an 18x simulation speedup.Peer Reviewe