Compile-time support for thread-level speculation

Una de las principales preocupaciones de las ciencias de la computación es el estudio de las capacidades paralelas tanto de programas como de los procesadores que los ejecutan. Existen varias razones que hacen muy deseable el desarrollo de técnicas que paralelicen automáticamente el código. Entre ellas se encuentran el inmenso número de programas secuenciales existentes ya escritos, la complejidad de los lenguajes de programación paralelos, y los conocimientos que se requieren para paralelizar un código. Sin embargo, los actuales mecanismos de paralelización automática implementados en los compiladores comerciales no son capaces de paralelizar la mayoría de los bucles en un código [1], debido a la dependencias de datos que existen entre ellos [2]. Por lo tanto, se hace necesaria la búsqueda de nuevas técnicas, como la paralelización especulativa [3-5], que saquen beneficio de las potenciales capacidades paralelas del hardware y arquitecturas multiprocesador actuales. Sin embargo, ésta y otras técnicas requieren la intervención manual de programadores experimentados. Antes de ofrecer soluciones alternativas, se han evaluado las capacidades de paralelización de los compiladores comerciales, exponiendo las limitaciones de los mecanismos de paralelización automática que implementan. El estudio revela que estos mecanismos de paralelización automática sólo alcanzan un 19% de speedup en promedio para los benchmarks del SPEC CPU2006 [6], siendo este un resultado significativamente inferior al obtenido por técnicas de paralelización especulativa [7]. Sin embargo, la paralelización especulativa requiere una extensa modificación manual del código por parte de programadores. Esta Tesis aborda este problema definiendo una nueva cláusula OpenMP [8], llamada ¿speculative¿, que permite señalar qué variables pueden llevar a una violación de dependencia. Además, esta Tesis también propone un sistema en tiempo de compilación que, usando la información sobre los accesos a las variables que proporcionan las cláusulas OpenMP, añade automáticamente todo el código necesario para gestionar la ejecución especulativa de un programa. Esto libera al programador de modificar el código manualmente, evitando posibles errores y una tediosa tarea. El código generado por nuestro sistema enlaza con la librería de ejecución especulativamente paralela desarrollada por Estebanez, García-Yagüez, Llanos y Gonzalez-Escribano [9,10].Departamento de Informática (Arquitectura y Tecnología de Computadores, Ciencias de la Computación e Inteligencia Artificial, Lenguajes y Sistemas Informáticos

Deferred and atomic setting of scheduling attributes for ada

© Sáez Barona, S.; Real Sáez, J.; Crespo, A. | ACM, 2015. This is the author's version of the work. It is posted here for your personal use. Not for redistribution. The definitive Version of Record was published in Adda Letters, http://dx.doi.org/10.1145/2552999.2553010Deferred setting of scheduling attributes refers to a single operation that sets a new value for a scheduling attribute of a task at some future time. Although deferred setting of scheduling attributes is possible in Ada 2012, it is in a rather limited way: only deadline or CPU can be changed deferredly, either at a specified time or when the task is released from a suspension object. And only one of those two attributes at a time. Other scheduling attributes such as priority cannot have deferred setting by means of a single operation. This would be a convenient feature to have for schemes such as job partitioning, task splitting, or mode changes. Another issue is the absence of operations for atomically changing several parameters at a time, which would avoid scheduling issues specially on multiprocessors. In this paper we explore a proposal aimed at correcting these two drawbacks. On one hand, we want to be able to change more attributes, not only deadlines, deferredly or immediately. On the other hand, we want to atomically change (now or later) a set of attributes, thereby avoiding scheduling artifacts that arise from sequentially changing several attributes, specially when the CPU is one of them. Rather than providing a number of library operations for postponing the setting of a variety of scheduling attributes, we propose to encapsulate the scheduling attributes of each task i n a single t agged type that can be extended with more attributes for specific applications if neededSáez Barona, S.; Real Sáez, JV.; Crespo, A. (2013). Deferred and atomic setting of scheduling attributes for ada. Ada Letters. 33(2):97-108. doi:10.1145/2552999.2553010S9710833

Adicción al smartphone y violencia familiar en adolescentes de 13 a 17 años de Santa Anita, Lima 2021

El presente estudio tuvo por objetivo general el de identificar la relación entre la adicción al smartphone y la violencia familiar en adolescentes de 13 a 17 años del distrito de Santa Anita, en Lima, en el año 2021. En cuanto a la metodología, la investigación fue de tipo básica, con diseño no experimental y de nivel correlacional, mientras que los instrumentos utilizados para el propósito de la misma fueron la Escala de Adicción al Smartphone – EAS, de Isabel Cueva, y el Cuestionario de Violencia Familiar – VIFA, de Livia Altamirano y Reyli Castro. Como resultado general, se obtuvo que hay un valor de p=0.000 y de Rho=0.424 para la correlación entre la adicción al smartphone y la violencia familiar. De tal manera, se concluyó que existe relación directa y de nivel moderado entre la variable de adicción al smartphone y la variable de violencia familiar en los adolescentes de 13 a 17 años del distrito de Santa Anita

16th International Conference on Computational and Mathematical Methods in Science and Engineering, CMMSE 2016

Producción CientíficaTransactional Memory (TM) is a technique that aims to mitigate the performance losses that are inherent to the serialization of accesses in critical sections. Some studies have shown that the use of TM may lead to performance improvements, despite the existence of management overheads. However, the relative performance of TM, with respect to classical critical sections management depends greatly on the actual percentage of times that the same data is handled simultaneously by two transactions. In this paper, we compare the relative performance of the critical sections provided by OpenMP with respect to two Software Transactional Memory (STM) implementations. These three methods are used to manage concurrent data accesses in ATLaS, a software-based, Thread-Level Speculation (TLS) system. The complexity of this application makes it extremely di cult to predict whether two transactions may conflict or not, and how many times the transactions will be executed. Our experimental results show that the STM solutions only deliver a performance comparable to OpenMP when there are almost no conflicts. In any other case, their performance losses make OpenMP the best alternative to manage critical sections.MICINN (Spain) and ERDF program of the European Union: HomProg-HetSys project (TIN2014-58876-P), CAPAP-H5 network (TIN2014-53522-REDT), and COST Program Action IC1305: Network for Sustainable Ultrascale Computing (NESUS)

BFCA+: Automatic Synthesis of Parallel Code with TLS Capabilities

Producción CientíficaParallelization of sequential applications requires extracting information about the loops and how their variables are accessed, and afterwards, augmenting the source code with extra code depending on such information. In this paper we propose a framework that avoids such an error-prone, time-consuming task. Our solution leverages the compile-time information extracted from the source code to classify all variables used inside each loop according to their accesses. Then, our system, called BFCA+, automatically instruments the source code with the necessary OpenMP directives and clauses to allow its parallel execution, using the standard shared and private clauses for variable classification. The framework is also capable of instrumenting loops for speculative parallelization, with the help of the ATLaS runtime system, that defines a new speculative clause to point out those variables that may lead to a dependency violation. As a result, the target loop is guaranteed to correctly run in parallel, ensuring that its execution follows sequential semantics even in the presence of dependency violations. Our experimental evaluation shows that the framework not only saves development time, but also leads to a faster code than the one manually parallelized.MICINN (Spain) and ERDF program of the European Union: HomProg-HetSys project (TIN2014-58876-P), CAPAPH5 network (TIN2014-53522-REDT), and COST Program Action IC1305: Network for Sustainable Ultrascale Computing (NESUS)

An OpenMP Extension that Supports Thread-Level Speculation

Producción CientíficaOpenMP directives are the de-facto standard for shared-memory parallel programming. However, OpenMP does not guarantee the correctness of the parallel execution of a given loop if runtime data dependences arise. Consequently, many highly-parallel regions cannot be safely parallelized with OpenMP due to the possibility of a dependence violation. In this paper, we propose to augment OpenMP capabilities, by adding thread-level speculation (TLS) support. Our contribution is threefold. First, we have defined a new speculative clause for variables inside parallel loops. This clause ensures that all accesses to these variables will be carried out according to sequential semantics. Second, we have created a new, software-based TLS runtime library to ensure correctness in the parallel execution of OpenMP loops that include speculative variables. Third, we have developed a new GCC plugin, which seamlessly translates our OpenMP speculative clause into calls to our TLS runtime engine. The result is the ATLaS C Compiler framework, which takes advantage of TLS techniques to expand OpenMP functionalities, and guarantees the sequential semantics of any parallelized loop.Castilla-Leon Regional Government (VA172A12-2, PIRTU); Ministerio de Industria, Spain (CENIT OCEANLIDER); MICINN (Spain) and the European Union FEDER (MOGECOPP project TIN2011- 25639, CAPAP-H3 network TIN2010-12011-E, CAPAPH4 network TIN2011-15734-E)

Caracterización de Explotaciones Caprinas: Sistemas Extensivos de la Sierra Norte de Sevilla

Andalucía es la comunidad autónoma española con mayor censo de ganado caprino lechero. Sin embargo, por tratarse de un ganado tradicionalmente asociado a sistemas semi-extensivos, falta aun mucha información sobre el funcionami~nto de las explotaciones, que, por otro lado, son muy diversas respecto al grado de intensificación, tamaño y tipo de ordeño. Por ello, desde el Departamento de Ciencias Agroforestales de la EUITA de Sevilla y en colaboración con la Federación de Asociaciones y Empresas Cooperativas Andaluzas (FAECA) se está trabajando en el conocimiento de los sistemas de caprino lechero de esta comunidad autónoma y sus posibilidades de mejora. Esta comunicación es una síntesis de la información generada en el estudio de una de las comarcas en las que se ha trabajado (Gousse, 1998), en la que predominan explotaciones con diversidad de ganado, pequeñas, de carácter semiextensivo y con ordeño manual

Projects to encourage female students in STEM areas

[EN] Today, the number of female students that enrol in degrees related to Science, Technology, Engineering and Mathematics (STEM) areas is quite low. So, numerous initiatives have arisen to promote these degrees and encourage female students in these areas. In this context, the EuLES Network (u-Learning Environments in Higher Education), an interdisciplinary network created in 2010 at the University of Zaragoza (Spain) to foster research, interaction, cooperation and transfer of knowledge and technologies related to learning and open education, has developed two projects oriented to High School Students: “WikinformáticA! en Aragon” and “Women in STEM by EuLES”. WikinformáticA! en Aragón is a competition for student groups in which they develop a wiki on prominent women in the history of Information and Communication Technology (ICT). The objective is the visibility of women involved in technology. The purpose of the Women in STEM project is to offer testimonies of women in Science, Technology, Engineering and Mathematics to encourage scientific vocations, especially in young people and girls. The project consists of conducting video interviews of women who work or study in these disciplines. All the videos, along with a short biography, are posted on the web.This work was supported by the Universidad de Zaragoza (Spain) [PIIDUZ_18_331].Allueva-Pinilla, AI.; Alejandre-Marco, JL.; Lozano Albalate, MT.; Trillo-Lado, R.; Ilarri-Artigas, S.; Sánchez-Azqueta, C.; Fuentes-Broto, L.... (2019). Projects to encourage female students in STEM areas. En HEAD'19. 5th International Conference on Higher Education Advances. Editorial Universitat Politècnica de València. 1347-1354. https://doi.org/10.4995/HEAD19.2019.9474OCS1347135

Treatment with tocilizumab or corticosteroids for COVID-19 patients with hyperinflammatory state: a multicentre cohort study (SAM-COVID-19)

Objectives: The objective of this study was to estimate the association between tocilizumab or corticosteroids and the risk of intubation or death in patients with coronavirus disease 19 (COVID-19) with a hyperinflammatory state according to clinical and laboratory parameters. Methods: A cohort study was performed in 60 Spanish hospitals including 778 patients with COVID-19 and clinical and laboratory data indicative of a hyperinflammatory state. Treatment was mainly with tocilizumab, an intermediate-high dose of corticosteroids (IHDC), a pulse dose of corticosteroids (PDC), combination therapy, or no treatment. Primary outcome was intubation or death; follow-up was 21 days. Propensity score-adjusted estimations using Cox regression (logistic regression if needed) were calculated. Propensity scores were used as confounders, matching variables and for the inverse probability of treatment weights (IPTWs). Results: In all, 88, 117, 78 and 151 patients treated with tocilizumab, IHDC, PDC, and combination therapy, respectively, were compared with 344 untreated patients. The primary endpoint occurred in 10 (11.4%), 27 (23.1%), 12 (15.4%), 40 (25.6%) and 69 (21.1%), respectively. The IPTW-based hazard ratios (odds ratio for combination therapy) for the primary endpoint were 0.32 (95%CI 0.22-0.47; p < 0.001) for tocilizumab, 0.82 (0.71-1.30; p 0.82) for IHDC, 0.61 (0.43-0.86; p 0.006) for PDC, and 1.17 (0.86-1.58; p 0.30) for combination therapy. Other applications of the propensity score provided similar results, but were not significant for PDC. Tocilizumab was also associated with lower hazard of death alone in IPTW analysis (0.07; 0.02-0.17; p < 0.001). Conclusions: Tocilizumab might be useful in COVID-19 patients with a hyperinflammatory state and should be prioritized for randomized trials in this situatio