Worst-Case Communication Overhead in a Many-Core based Shared-Memory Model

National audienceWith emerging many-core architectures, using on-chip shared memories is an interesting approach because it provides high bandwidth and high throughput data exchange. Such a feature is usually implemented as a multi-bus multi-banked memory. Since predicting timing behavior is key to efficient design and verification of embedded real-time systems, the question that arises is how to evaluate the access time for one memory access of a given task while others may concurrently access the same memory-bank at t the same time. In this paper, we give the answers for a subset of streaming applications modeled like CSDF Model of Computation and implemented in Kalray’s MPPA chip

Design-Space Exploration of Stream Programs through Semantic-Preserving Transformations

Stream languages explicitly describe fork-join parallelism and pipelines, offering a powerful programming model for many-core Multi-Processor Systems on Chip (MPSoC). In an embedded resource-constrained system, adapting stream programs to fit memory requirements is particularly important. In this paper we present a design-space exploration technique to reduce the minimal memory required when running stream programs on MPSoC; this allows to target memory constrained systems and in some cases obtain better performance. Using a set of semantically preserving transformations, we explore a large number of equivalent program variants; we select the variant that minimizes a buffer evaluation metric. To cope efficiently with large program instances we propose and evaluate an heuristic for this method. We demonstrate the interest of our method on a panel of ten significant benchmarks. As an illustration, we measure the minimal memory required using a multi-core modulo scheduling. Our approach lowers considerably the minimal memory required for seven of the ten benchmarks

Using the Spring Physical Model to Extend a Cooperative Caching Protocol for Many-Core Processors

International audienceAs the number of embedded cores grows up, the off-chip memory wall becomes an overwhelming bottleneck. As a consequence, it is more and more prevalent to efficiently exploit on-chip data storage. In a previous work, we proposed a data sliding mechanism that allows to store data onto our closest neighborhood, even under heavy stress loads. However, each cache block is allowed to migrate only one time to a neighbor's cache (e.g. 1-Chance Forwarding). In this paper, we propose an extension of our mechanism in order to expand the cooperative caching area. Our work is based on an adaptive physical model, where each cache block is considered as a mass connected to a spring. This technique constrains data migration according to the spring constant and the difference of work-loads between cores. This adaptive data sliding approach leads to a balanced spread of data on the chip and therefore improves on-chip storage. On-chip data access has been evaluated using an analytical approach. Results show that the extended data sliding increases the global cache hit rate on the chip, especially in the context of juxtaposed hot spots

Reducing Memory Requirements of Stream Programs by Graph Transformations

International audienceStream languages explicitly describe fork-join parallelism and pipelines, offering a powerful programming model for many-core Multi-Processor Systems on Chip (MPSoC). In an embedded resource-constrained system, adapting stream programs to fit memory requirements is particularly important. In this paper we present a new approach to re- duce the memory footprint required to run stream programs on MPSoC. Through an exploration of equivalent program variants, the method selects parallel code minimizing mem- ory consumption. For large program instances, a heuristic accelerating the exploration phase is proposed and evalu- ated. We demonstrate the interest of our method on a panel of ten significant benchmarks. Using a multi-core modulo scheduling technique, our approach lowers considerably the minimal amount of memory required to run seven of these benchmarks while preserving throughput

Self-Timed Periodic Scheduling For Cyclo-Static DataFlow Model

International audienceReal-time and time-constrained applications programmed on many-core systems can suffer from unmet timing constraints even with correct-by-construction schedules. Such unexpected results are usually caused by unaccounted for delays due to resource sharing (e.g. the communication medium). In this paper we address the three main sources of unpredictable behaviors: First, we propose to use a deterministic Model of Computation (MoC), more specifically, the well-formed CSDF subset of process networks; Second, we propose a run-time management strategy of shared resources to avoid unpredictable timings; Third, we promote the use of a new scheduling policy, the so-said Self-Timed Periodic (STP) scheduling, to improve performance and decrease synchronization costs by taking into account resource sharing or resource constraints. This is a quantitative improvement above state-of-the-art scheduling policies which assumed fixed delays of inter-processor communication and did not take correctly into account subtle effects of synchronization

Sites géologiques touristiques en Abitibi-Témiscamigue

Les Cahiers présentent ici les résultats d'un projet de recherche conduit par un groupe d'étudiants du Collège de l'Abitibi-Témiscamingue au cours de l'été de 1983. Tout au long de ces quelque cent pages, les auteurs nous invitent à découvrir dix sites géologiques de la région, choisis pour leur beauté et l'intérêt qu'ils sauront susciter auprès des touristes. Des photos couleur, des cartes et des croquis viennent agrémenter un texte déjà très éclairant par lui-même, et le tout ainsi formé se présente comme une invitation à la découverte, un défi nouveau pour une nouvelle génération de touristes. «Sites géologiques touristiques en Abitibi-Témiscamingue» constitue donc une première pour le monde touristique régional et sans doute sera-t-il reçu comme une bouffée d'air frais dans les bureaux et kiosques des nombreuses associations vouées au développement du tourisme en Abitibi-Témiscamingue

Sports et publicités

Les sports semblent être omniprésents dans les publicités affichées et télévisées en France. Cette légitimation sociale et communicationnelle se double d’un intérêt particulier lorsqu’il s’agit d’analyser les rapports sociaux aux corps. Ici, l’exemple de la saleté est précisé à partir d’un corpus large (N = 500 publicités affichées, 70 télévisées). La mise à distance de cette saleté caractérise les communications publicitaires à partir des sports. Cette distanciation est analysée à partir des théories de Norbert Elias, d’Erving Goffman et de David Le Breton. La publicité sportive apparaît sans tache et sans odeur.It seems that sports are everywhere today in advertisements on billboards and television in France. This communicational and social acceptance is particularly interesting when social relations with bodies are analysed. Here, the example of dirtiness receives particular attention using a broad corpus (N= 500 billboard ads, 70 TV ads). Careful distancing of any dirtiness characterises advertising messages when sports are involved. This distancing is analysed using the theories of Norbert Elias, Erving Goffman and David Le Breton. Sports advertising appears spotless and odourless

DSL Stream Programming on Multicore Architectures

International audienceTo effectively program parallel architectures it is important to combine a simple expression of the parallelism with efficient compiler optimizations. We propose a novel stream programming framework based on two domain specific languages that separate these two issues. A high-level declarative language allows to describe data dependencies between filters while an intermediate language enables powerful optimizations through a set of stream graph transformations. This two level approach offers a clean separation between the issue of programming complexity and the issue of target specific optimization

Measurement invariance of the Marijuana Motives Measure among men and women using Stop Cannabis App

Motives to use cannabis play a central role in the development and maintenance of problematic cannabis use and previous studies stressed sex-related differences on motives to use cannabis. However, motives cannot be validly compared in men and women without first establishing the measurement invariance across sex. Therefore, the aim of the study is to (1) examine for the first time the measurement and structural invariance of the Marijuana Motives Measure (MMM) across sex, and (2) to investigate the motives for cannabis use that best explain problematic use. 2951 (41.7% women) users of the "Stop cannabis" smartphone app of which 99.8% reported having used cannabis in the last three months completed an online MMM and ASSIST to assess the severity of their problematic cannabis use. Multigroup confirmatory factor analyses supported measurement invariance across sex, whereas structural invariance was not confirmed. Indeed, group comparisons indicated that women reported greater coping motives then men whereas men showed greater social motives than women. A multiple linear regression analysis showed that only coping and conformity motives were significantly associated with greater problematic cannabis use, whereas neither sex nor the sex by motives interactions were significantly related to problematic cannabis use. The MMM appears to function comparably across men and women. Therefore, sex-related comparisons on the questionnaire can be considered valid. Coping and conformity motives may play a central role part in the development of marijuana use problems which may hold implications for intervention development and public policy

228 Blood pressure in HIV-infected patients

ObjectifveTo determine the prevalence of hypertension in a cohort of HIV-infected patients (HIV+).MethodsHIV+ patients were enrolled consecutively at ambulatory cardiology consultation. We evaluated:cardiovascular risk factors,office blood pressure,24 hours ambulatory blood pressure monitoring (ABPM).We identified patients with known hypertension, masked hypertension and white-coat effect.Results258 HIV+ patients (mean age 49±7 ans, 91% men) were consecutively included in this study between 2005 and 2009. Cardiovascular risk factors were as follows: 52% had dyslipidemia, 51% were active smokers, 40% with known hypertension and 9% were diabetics. Body mass index of the entire cohort was 24±4kg/mΣ and 89% were under antiretrovirals. Data on blood pressure are depicted in Table 1. 19% (29) were discovered to have hypertension.ConclusionHypertension is frequent in HIV-infected patients and more and more common with aging. The number of non-dipper HIV+ was high in this cohort. Studies on the impact of HIV infection and antiretrovirals on the autonomic nervous system should be performed.ParametersN=258Office systolic BP, mmHg131±19Office diastolic BP, mmHg81±10Mean 24h-systolic BP, mmHg125±13Mean 24-diastolic BP, mmHg77±9Daytime systolic BP, mmHg129±13Daytime diastolic BP, mmHg80±9Nighttime systolic BP, mmHg115±17Nighttime diastolic BP, mmHg68±10BP profile in known hypertensive patientsN=103Number of patients with appropriate BP control, %45%Number of patients with white-coat effect, %17%Non dipper, %43% in known hypertensive patients 39% in unknown hypertensive patient