Browsing by Subject "Proposals"

Now showing 1 - 4 of 4
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    Chaining transactions for effective concurrency management in hardware transactional memory
    (IEEE Computer Society, 2024-12-03) Nicolas Conesa, Víctor; Titos Gil, Rubén; Fernández Pascual, Ricardo; Acacio, Manuel E.; Ros Bardisa, Alberto; Ingeniería y Tecnología de Computadores
    Hardware Transactional Memory (HTM) offers the opportunity to ease parallel programming. However, driven by hardware limitations, commercial implementations eschew the complexity involved in early sophisticated proposals from academia, and, among other things, opt for simple conflict resolution policies that inevitably increase transaction aborts. To increase thread level parallelism, previous works propose conflict resolution schemes that, instead of aborting, add a second level of speculation consisting in using not-yet-committed data from another transaction. This policy, which we refer to as requester-speculates, has not yet been considered in the context of the kind of best-effort HTM support provided by commercial processors. This work proposes CHAining TransactionS (CHATS), a simple yet effective realization of the requester-speculates con-flict resolution policy in which cyclic dependencies between transactions are avoided and the commit ordering respects the dependencies that transactions make once speculative values are communicated. The ultimate result is a best-effort HTM implementation that forces a partial order between transactions in a way that ensures effective utilization of forwarded data and that gets away from the complexity of previous proposals. Simulations using gem5 demonstrate the effectiveness of CHATS in both commercial-like setups and academic state-of-the-art best-effort systems (22% and 16% reduction in execution time, on average, respectively). These improvements are achieved by requiring less than 280 bytes of extra storage.
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    Los futuros maestros ante el problema de la contaminación de los mares por plásticos y el consumo.
    (2018-10-11) Jaén, Mercedes; Esteve, Patricia; Banos-González, Isabel; Didáctica de las Ciencias Experimentales
    En este trabajo se aborda desde el ámbito educativo el problema de la contaminación de los mares por residuos. En un escenario en el que la contaminación por plásticos se ha convertido en un problema de orden global, indagamos sobre las ideas, actitudes y competencias didácticas que muestran los futuros maestros cuando se enfrentan a los hábitos de consumo de nuestra sociedad actual. Se analiza la puesta en práctica de una intervención educativa en la que, a partir de una situación problemática vinculada a la contaminación por plásticos, los estudiantes realizan tareas en las que exploran el problema y algunos de sus hábitos de consumo. Sus respuestas indican que establecen relaciones causales entre ciertas actividades humanas y las problemáticas ambientales, y se muestran dispuestos a asumir compromisos para reducir sus consumos, aunque lo hacen desde un escenario limitado a su entorno y sus intereses. Al implementar esta problemática en Primaria, la mayoría utilizan un modelo simple basado en la información. Se han identificado algunas dificultades al concretar estrategias que permitan desarrollar el pensamiento crítico en los niños y niñas de Primaria.
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    Más allá del aula. Un análisis de las salidas de campo para enseñar las inundaciones desde la perspectiva del profesorado en formación
    (Universidad de Murcia, Servicio de Publicaciones, 2025) Morote Seguido, Álvaro Francisco; Sin departamento asociado
    The 2024 DANA, which has severely affected the province of Valencia with a toll of 227 fatalities, has highlighted the need to strengthen education on flood risk. This study aims to analyse different field works proposals designed to address this issue in Primary Education. To this end, 13 proposals developed by students of the Bachelor's Degree in Primary Education at the University of Valencia (Spain) over six academic years (2019-2020 to 2024-2025) have been reviewed. These activities were designed by student groups from various specializations (Arts and Humanities, Physical Education, Science and Mathematics, Therapeutic Pedagogy) related to topics such as climatology, natural hazards, and water resources. The results reveal that 53.8% of the field works address these proposals through fundamental knowledge, such as flood risk, while 23.1% focus on climate change. However, half of them do not include risk cartography in their materials, and those that do use tools like the viewer of the PATRICOVA and SNCZI. Additionally, half of the proposals refer to historical floods and encourage students to propose solutions. In conclusion, these experiences are essential for geographic education, although it is crucial to improve the use of cartography and the formulation of solutions to enhance socio-territorial resilience in the face of present and future climate change scenarios.
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    Secure prefetching for secure cache systems
    (IEEE Computer Society, 2024-12-03) Nath, Sumon; Navarro Torres, Agustín; Ros Bardisa, Alberto; Panda, Biswabandan; Ingeniería y Tecnología de Computadores
    Transient execution attacks like Spectre and its vari-ants can cause information leakage through a cache hierarchy. There are two classes of techniques that mitigate speculative execution attacks: delay-based and invisible speculation. Invisible speculation-based techniques like GhostMinion are the high-performing yet secure techniques that mitigate all kinds of spec-ulative execution attacks. Similar to a cache system, hardware prefetchers can also cause speculative information leakage. To mitigate it, GhostMinion advocates on-commit prefetching on top of strictness ordering in the cache system. Our experiments show that the GhostMinion cache system interacts negatively with the hardware prefetchers leading to redundant traffic between different levels of cache. This traffic causes contention and increases the miss latency leading to performance loss. Next, we observe that on-commit prefetching enforced by GhostMinion leads to nerformance loss as it affects the prefetcher timeliness. We perform the first thorough analysis of the interaction between state-of-the-art prefetching techniques and the secure cache system. Based on this, we propose two microarchitectural solutions that ensure high performance while designing secure prefetchers on top of secure cache system. The first solution detects and filters redundant traffic when updating the cache hierarchy non-speculatively. The second solution ensures the timeliness of the prefetcher to compensate for the delayed triggering of prefetch requests at commit, resulting in a secure yet high-performing prefetcher. Overall, our enhancements are secure and provide synergistic interactions between hardware prefetchers and a secure cache system. Our experiments show that our filter consistently improves the performance of secure cache systems like GhostMinion in the presence of state-of-the-art prefetchers (by 1.9% for single-core and 19.0% for multi-core for the top-performing prefetcher). We see a synergistic behavior of the filter with our proposed secure prefetcher, which leads to a further increase in performance by 6.3% and 23.0% (over the top-performing prefetcher), for single-core and multi-core systems, respectively. Our enhancements are extremely lightweight incurring a storage overhead of 0.59 KB per core.