Hardware support for Local Memory Transactions on GPU Architectures

Graphics Processing Units (GPUs) are popular hardware accelerators for data-parallel applications, enabling the execution of thousands of threads in a Single Instruction - Multiple Thread (SIMT) fashion. However, the SIMT execution model is not efficient when code includes critical sections to protect the access to data shared by the running threads. In addition, GPUs offer two shared spaces to the threads, local memory and global memory. Typical solutions to thread synchronization include the use of atomics to implement locks, the serialization of the execution of the critical section, or delegating the execution of the critical section to the host CPU, leading to suboptimal performance. In the multi-core CPU world, transactional memory (TM) was proposed as an alternative to locks to coordinate concurrent threads. Some solutions for GPUs started to appear in the literature. In contrast to these earlier proposals, our approach is to design hardware support for TM in two levels. The first level is a fast and lightweight solution for coordinating threads that share the local memory, while the second level coordinates threads through the global memory. In this paper we present GPU-LocalTM as a hardware TM (HTM) support for the first level. GPU-LocalTM offers simple conflict detection and version management mechanisms that minimize the hardware resources required for its implementation. For the workloads studied, GPU-LocalTM provides between 1.25-80X speedup over serialized critical sections, while the overhead introduced by transaction management is lower than 20%.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Hardware support for scratchpad memory transactions on GPU architectures

Graphics Processing Units (GPUs) have become the accelerator of choice for data-parallel applications, enabling the execution of thousands of threads in a Single Instruction - Multiple Thread (SIMT) fashion. Using OpenCL terminology, GPUs offer a global memory space shared by all the threads in the GPU, as well as a low-latency local memory space shared by a subset of the threads. The latter is used as a scratchpad to improve the performance of the applications. We propose GPU-LocalTM, a hardware transactional memory (TM), as an alternative to data locking mechanisms in local memory. GPU-LocalTM allocates transactional metadata in the existing memory resources, minimizing the storage requirements for TM support. In addition, it ensures forward progress through an automatic serialization mechanism. In our experiments, GPU-LocalTM provides up to 100X speedup over serialized execution.This work has been supported by projects TIN2013-42253-P and TIN2016-80920-R, from the Spanish Government, P11-TIC8144 and P12-TIC1470, from Junta de Andalucía, and Universidad de Málaga, Campus de Excelencia Internacional, Andalucía Tech

Meeting the traffic requirements of residential users in the next decade with current FTTH standards: How much? How long?

Traffic demand in access networks has grown in recent years, and service providers need to upgrade their infrastructure to the latest access standards. While fiber has become the preferred technology of choice in access networks, there are many fibre access technologies available inthe market. This poses challenging questions to operators that are not always easy to answer: How to upgrade? What technology and for howlong wil it cope with the demands? In this article we model the traffic forecast in access networks for the next decade and analyze possible upgradescenarios of fibre access networks, concluding which of the NG-PON flavors could better fit the demand.The authors would like to acknowledge the support of the Spanish project TEXEO (grant no. TEC2016-80339-R), and the EU-funded project Fed4Fire (grant no. 318389) to the development of this work

The sigma-1 receptor as key common factor in cocaine and food seeking behaviors

Addiction and eating disorders involve brain reward circuits. A previous history of binge eating predisposes to addictive behavior, while the cessation of exposure to drugs of abuse leads to reward activities, including intake of tasty foods. Cocaine use is associated with a decrease in food intake, with reversal after the drug use is stopped. Exciting new findings show that receptors for the 'hunger' hormone, ghrelin, directly interact with the sigma-1 receptors (1R), which is a target of cocaine. 1R are key players in regulating dopaminergic neurotransmission and ghrelin-mediated actions. This review focuses on the 1 receptor as general neuroendocrine regulator by directly interacting with neuronal G-protein-coupled receptors. This review also covers the early mechanisms by which cocaine binding to 1 blocks the food-seeking behavior triggered by ghrelin. Such new findings appear as fundamental to understand common mechanisms in drug addiction and eating disorders

Plauciano: la amenaza de la domus severiana.

En el trabajo presentamos una visión sintética del ascenso y caída de un personaje no demasiado tratado por la historiografía moderna, Plauciano. Sin embargo, tuvo un papel esencial en el acceso al poder de Septimio Severo y también durante los años en que fue prefecto del pretorio, desde 197 hasta enero de 205, cuando murió de forma violenta. De él, dicen las fuentes antiguas que era pariente, pero sobre todo, amigo muy próximo del emperador. Su cercanía a este, más que el propio cargo, le permitió obtener un poder político y económico casi omnímodo, por lo que fue considerado en su tiempo como un cuarto césar. Incluso casó a su hija Plautilla con el heredero al trono, Caracalla. Precisamente sus cotas de poder y su proximidad a Septimio suscitaron recelos y envidias principalmente en el entorno imperial que finalmente provocaron su caída y su muerte inmediata, aunque las fuentes antiguas que escriben estos acontecimientos no coinciden en la narración de los hechos.This paper presents a synthetic view of the rise and fall of a little-treated character in modern historiography, Plautian. However, this person played a key role in the accession to power of Septimius Severus and during the years he was Praetorian Prefect, from 197 to January 205, when he died violently. Ancient sources state that he was a patient person, and above all, a very close friend of the Emperor. His proximity to the Emperor, rather than his position proper, enabled him to obtain almost an absolute political and economic power, being considered at the time as a fourth Caesar. He even managed that his daughter Plautilla married the heir of the Caracalla throne. It is precisely his power and his proximity to Septimius that raised suspicions and jealousies among the Imperial community, leading ultimately to his downfall and his immediate death; though the ancient sources that describe these events do not necessary coincide

Principales fantasías sexuales en jóvenes españoles y diferencias en función de variables sociodemográficas

Introducción: El concepto fantasía sexual define cualquier pensamiento o imagen que provoca excitación en una persona, sea una historia real, una elaboración imaginaria o un pensamiento fugaz. Son frecuentes durante la masturbación o las relaciones sexuales pero también aparecen en situaciones no sexuales. Nuestro objetivo es ana- lizar la prevalencia de las fantasías sexuales más comunes entre los jóvenes, así como estudiar posibles diferencias según distintas variables demográficas. Metodolo- gía: Se analizaron las respuestas de 192 hombres y 208 mujeres entre 18 y 26 años (m = 21,8; dt = 2,2), que contestaron de forma online al cuestionario sfq (Wilson, 1978), en su adaptación española de Sierra y cols. (2006) versionada para este estu- dio. Resultados: La edad media de inicio de fantasías sexuales es de 13,5 años (hombres: 12,7 y mujeres: 14,3; t = -6,38; p < 0,05). Se hallaron diferencias significa- tivas en el número de fantasías sexuales que presentaban ambos sexos (t = -2,062; p < 0,05), siendo la media mayor en mujeres, y se encontró una media significativa- mente superior en el grupo de jóvenes con orientación bisexual respecto al de orien- tación heterosexual (f = 9,607; p < 0,05). Entre las cinco fantasías sexuales más prevalentes en cada sexo, cuatro de ellas coincidían en hombres y mujeres. Conclu- siones: Los hombres experimentan fantasías sexuales a una edad más temprana que las mujeres. Existen diferencias significativas en el número de fantasías sexuales en función del género y la orientación sexual, pero no en su contenido.Introduction: The concept “sexual fantasy” defines any thought or image that triggers excitation in a person. It might be a real story, a drawing imaginary or a fleeting thought. They are common during masturbation or sexual intercourse but also in non-sexual situations. The aim of this study is to analyze the prevalence of the most common sexual fantasies among youth, as well as to study possible differences based on demo- graphic variables. Methodology: The responses of 192 men and 208 women aged between 18 and 26 (m = 21.8; sd = 2.2), to our particular online version of the Sierra et al. (2006) Spanish adaptation of the sfq (Wilson, 1978) were analyzed. Results: The mean age of the onset of sexual fantasies is 13.5 years (men: 12.7 and women: 14.3; t = -6.381; p < 0.05). Significant differences on the number of sexual fantasies based on sex were found (t = -2.062; p < 0.05), in which women reported a higher mean. A significant higher mean in the bisexual orientation youth group compared to the hetero- sexual orientation group was also found (f = 9.607; p < 0.05). Among the five most prevalent sexual fantasies in each sex, men and women shared four of them. Conclu- sions: Men experience sexual fantasies at an earlier age than women. There are sig- nificant differences in the amount of sexual fantasies according to sex and sexual ori- entation, but not about the subject matter

Redox-dependent and redox-independent functions of Caenorhabditis elegans thioredoxin 1

Thioredoxins (TRX) are traditionally considered as enzymes catalyzing redox reactions. However, redox-independent functions of thioredoxins have been described in different organisms, although the underlying molecular mechanisms are yet unknown. We report here the characterization of the first generated endogenous redox-inactive thioredoxin in an animal model, the TRX-1 in the nematode Caenorhabditis elegans. We find that TRX-1 dually regulates the formation of an endurance larval stage (dauer) by interacting with the insulin pathway in a redox-independent manner and the cGMP pathway in a redox-dependent manner. Moreover, the requirement of TRX-1 for the extended longevity of worms with compromised insulin signalling or under calorie restriction relies on TRX-1 redox activity. In contrast, the nuclear translocation of the SKN-1 transcription factor and increased LIPS-6 protein levels in the intestine upon trx-1 deficiency are strictly redox-independent. Finally, we identify a novel function of C. elegans TRX-1 in male food-leaving behaviour that is redox-dependent. Taken together, our results position C. elegans as an ideal model to gain mechanistic insight into the redox-independent functions of metazoan thioredoxins, overcoming the limitations imposed by the embryonic lethal phenotypes of thioredoxin mutants in higher organisms.NIH Office of Research Infrastructure P40 OD010440Spanish Ministry of Economy and Competitiveness BFU2015- 64408-PFondo Social Europeo BFU2015- 64408-PNational Institute of Allergy and Infectious Diseases of the National Institutes of Health R01AI07640