Optimizing Local Memory Allocation and Assignment Through a Decoupled Approach

International audienceSoftware-controlled local memories (LMs) are widely used to provide fast, scalable, power efficient and predictable access to critical data. While many studies addressed LM management, keeping hot data in the LM continues to cause major headache. This paper revisits LM management of arrays in light of recent progresses in register allocation, supporting multiple live-range splitting schemes through a generic integer linear program. These schemes differ in the grain of decision points. The model can also be extended to address fragmentation, assigning live ranges to precise offsets. We show that the links between LM management and register allocation have been underexploited, leaving much fundamental questions open and effective applications to be explored

A Polynomial Spilling Heuristic: Layered Allocation

Register allocation is one of the most important, and one of the oldest compiler optimizations. Its purpose is to map temporary variables to either machine registers or main memory locations and explicit load/store instructions. The latter option is referred to as spilling. This paper addresses the minimization of the spill code overhead, one of the di fficult problems in register allocation. We devised a heuristic approach called layered. It is rooted in the recent advances in SSA-based register allocation. As opposed to the conventional incremental spilling approaches, our method incrementally allocates clusters of variables. We describe a new polynomial method, the layered-optimal allocator, and demonstrate its quasi-optimiality on standard benchmarks and on two architectures.L'allocation de registres est l'une des premières et des plus importantes optimisations effectuées par les compilateurs. Elle a pour but d'associer aux variables temporaires du programme des registres de la machine ou des locations mémoires et d'insérer, dans le code, des instructions de load/store explicites, appelées vidage. Dans ce papier, nous nous intéressons à la minimisation des latences mémoires dues au code de vidage, un des problèmes difficiles en allocation de registres. Nous proposons une approche heuristique d'allocation par couches. Ce travail se base sur les récentes avancées en allocation de registres sous SSA. Contrairement à l'approche conventionnelle de vidage incrémental, notre méthode alloue les variables de manière incrémentale par groupe. Nous comparons notre approche, appelée allocation-optimale par couche, aux méthodes de l'état de l'art à une approche optimale et nous montrons l'allocation-optimale par couche est quasi-optimale sur des benchmarks standard et sur deux architectures différentes

Influence De La Géomorphologie Sur La Distribution Spatiale Des Peuplements De Boscia Senegalensis (Pers.) Lam. Ex Poir. Dans La Commune Rurale De Simiri (Ouest Niger)

B. senegalensis is a species with broad geographic distribution in the Sahel, especially in Niger, thanks to its special anatomical structures to withstand drought, high temperatures and poor soils. It presents and a heterogeneous distribution in the following areas topographic levels characteristic of the western Niger. This paper aimed to assess the distribution of B. senegalensis and its relationship with woody species through the description of the spatial structure of the point process following toposequences by Ripley's method stands. The study highlighted the gregarious distribution of B. senegalensis and the close relationship between B. senegalensis and other species. Indeed, the species is in competition with other species on the plateau where water resources are scarce. But B. senegalensis tolerate these species on the slopes and in the shallows where water resources are relatively large

Boscia Senegalensis (Pers.) Lam. ex Poir., une Espèce Ligneuse à Fortes Potentialités Ethnobotaniques et Bien Adaptée à la Sécheresse au Sahel : Synthèse Bibliographique

L’exploitation des ressources végétales notamment ligneuses constitue l’une des stratégies paysannes adoptées pour faire face aux déficits alimentaires surtout pour les ménages vulnérables. Cette synthèse bibliographique dresse l’état des lieux de quelques contributions scientifiques et techniques relatives à l’importance socio-économique et environnementale ainsi que quelques caractéristiques écologiques de Boscia senegalensis (Pers.) Lam. ex Poir.. L’exploitation minutieuse de documents scientifiques en ligne notamment des articles scientifiques et des thèses ainsi que les documents fournis par Sahara Sahel Food a servi à la réalisation de cette étude. Il ressort de l’analyse bibliographique que cette ressource revêt une importance capitale pour les communautés sahéliennes. Il s’agit de son importance dans l’alimentation humaine (surtout en période de soudure), son usage dans la pharmacopée traditionnelle, son importance dans le stockage traditionnel du niébé ainsi que son rôle dans l’alimentation du bétail. La grande particularité de l’espèce réside aussi dans sa forte capacité de résilience. En effet, au Sahel cet arbuste polycaule de la famille des Capparaceae occupe souvent des écosystèmes au stade ultime de dégradation. Cependant quelques cas de menaces ont été évoqués sur cette espèce. L’analyse de l’état des lieux des connaissances existantes sur B. senegalensis a permis ainsi de mettre en évidence le besoin urgent d’entreprendre des recherches scientifiques approfondies sur l’état actuel de ses peuplements, ses stratégies de reproduction ainsi que la caractérisation de ses variétés. Ces nouvelles connaissances, une fois acquises contribueront à formuler des recommandations soutenues pour sa valorisation au Niger. The exploitation of woody plant resources is one of the peasant strategies adopted in dealing with food shortages, especially for vulnerable households. This paper focuses on the inventory of some scientific and technical contributions relating to the socio-economic and environmental importance as well as some ecological characteristics of Boscia senegalensis (Pers.) Lam. ex Poir. Detailed study of scientific documents including scientific articles and theses as well as the documents provided by Sahara Sahel Food was used in this study. It, however, emerges based on the bibliographic analysis that this resource is of capital importance for Sahelian communities. This importance can be seen in human nutrition (especially in lean season), traditional pharmacopoeia, traditional cowpea storage as well as its role in livestock feed. The great peculiarity of the species also lies in its strong capacity for resilience. Indeed, in the Sahel this polycaule shrub of the Capparaceae family often occupies ecosystems at the final stage of degradation. However, some cases of threats have been mentioned in this species. The analysis of the current state of knowledge on B. senegalensis has thus made it possible to highlight the urgent need to undertake an in-depth scientific research on the current state of its stands, his reproductive strategies, and the characterization of its varieties. This new knowledge, once acquired, will help in formulating sustained recommendations for its valorization in Niger

Feasibility and safety of integrating mass drug administration for helminth control with seasonal malaria chemoprevention among Senegalese children: a randomized controlled, observer-blind trial

BACKGROUND: The overlap in the epidemiology of malaria and helminths has been identified as a potential area to exploit for the development of an integrated control strategy that may help to achieve elimination of malaria and helminths. A randomized, controlled, observer-blind trial was conducted to assess the feasibility and safety of combining mass drug administration (MDA) for schistosomiasis and soil transmitted helminths (STH) with seasonal malaria chemoprevention (SMC) among children living in Senegal. METHODS: Female and male children aged 1-14 years were randomized 1:1:1, to receive Vitamin A and Zinc on Day 0, followed by SMC drugs (sulfadoxine-pyrimethamine and amodiaquine) on Days 1-3 (control group); or praziquantel and Vitamin A on Day 0, followed by SMC drugs on Days 1-3 (treatment group 1); or albendazole and praziquantel on Day 0, followed by SMC drugs on Days 1-3 (treatment group 2). Safety assessment was performed by collecting adverse events from all children for six subsequent days following administration of the study drugs. Pre- and post-intervention, blood samples were collected for determination of haemoglobin concentration, malaria microscopy, and PCR assays. Stool samples were analyzed using Kato-Katz, Merthiolate-iodine-formalin and PCR methods. Urine filtration, PCR and circulating cathodic antigen tests were also performed. RESULTS: From 9 to 22 June 2022, 627 children aged 1-14 years were randomized into the three groups described above. Mild, transient vomiting was observed in 12.6% (26/206) of children in treatment group 2, in 10.6% (22/207) in group 1, and in 4.2% (9/214) in the control group (p = 0.005). Pre-intervention, the geometric mean value of Plasmodium falciparum parasite density was highest among children who received albendazole, praziquantel with SMC drugs. Post-intervention, the parasite density was highest among children who received SMC drugs only. Children who received praziquantel and SMC drugs had a lower risk of developing severe anaemia than their counterparts who received SMC drugs alone (OR = 0.81, 95% CI 0.13-5.00, p = 0.63). CONCLUSIONS: Integration of MDA for helminths with SMC drugs was safe and feasible among Senegalese children. These findings support further evaluation of the integrated control model. TRIAL REGISTRATION: The study is registered at Clinical Trial.gov NCT05354258

Approches découplées aux problèmes d'allocations de registres et de mémoires locales

Despite the benefit of the memory hierarchy, it is still essential, in order to reduce accesses to higher levels of memory, to have an efficient usage of registers and local memories (also called scratchpad memories) present in most embedded processors, graphical processors (GPUs) and network processors. During the compilation, from a source language to an executable code, there are two optimizations that are of utmost importance: the register allocation and the local memory allocation. In this thesis's report we are interested in decoupled approaches, solving separately the allocation and assignment problems, that helps to improve the quality of the register and local memory allocations. In the first part of this thesis we are interested in two aspects of the register allocation problem: the improvements of the just-in-time (JIT) register allocation and the spill minimization problem. We introduce the split register allocation which leverages the decoupled approach to improve register allocation in the context of JIT compilation. We experimentally validate the effectiveness of split register allocation and its portability with respect to register count variations, relying on annotations whose impact on the bytecode size is negligible. We introduce a new decoupled approach, called iterated-optimal allocation, which focus on the spill minimization problem. The iterated-optimal allocation algorithm achieves results close to optimal while offering pseudo-polynomial guarantees for SSA programs and fast allocations on general programs. In the second part of this thesis, we study how a decoupled local memory allocation can be proposed in light of recent progresses in register allocation. We first validate our intuition for decoupled approach to local memory allocation. Then, we study the local memory allocation in a more theoretical way setting the junction between local memory allocation for linearized programs and weighted interval graph coloring. We design and analyze a new variant of the ship-building problem called the submarine-building problem. We show that this problem is NP-complete on interval graphs, while it is solvable in linear time for proper interval graphs, equivalent to unit interval graphs. The submarine-building problem is the first problem that is known to be NP-complete on interval graphs, while it is solvable in linear time for unit interval graphs. In the third part of this thesis, we propose a heuristic-based solution, the clustering allocator, which decouples the local memory allocation problem and aims to minimize the allocation cost. The clustering allocator while devised for local memory allocation, it appears to be a very good solution to the register allocation problem. After many years of separation, this new algorithm seems to be a bridge to reconcile the local memory allocation and the register allocation problems.Malgré la hiérarchie mémoire utilisée dans les ordinateurs modernes, il convient toujours d'optimiser l'utilisation des registres du processeur et des mémoires locales gérées de manières logicielles (mémoires locales) présentes dans beaucoup de systèmes embarqués, de processeurs graphiques (GPUs) et de multiprocesseurs. Lors de la compilation, d'un code source vers un langage machine, deux optimisations de la mémoire revêtent une importance capitale : l'allocation de registres et l'allocation de mémoires locales. Dans ce manuscrit de thèse nous nous intéressons à des approches découplées, qui traitent séparément les problèmes d'allocation et d'assignation, permettant d'améliorer les allocations de registres et de mémoires locales. Dans la première partie de la thèse, nous nous penchons sur le problème de l'allocation de registres. Tout d'abord, nous proposons dans le contexte des compilateurs-juste-à-temps, une allocation de registres fractionnées (split register allocation). Avec cette approche l'allocation de registres est effectuée en deux étapes: une faite durant la phase de compilation statique et l'autre pendant la phase de compilation dynamique. Ce qui permet de réduire le temps d'exécution des programmes avec un impact négligeable sur le temps de compilation. Ensuite Nous introduisons une allocation de registres incrémentale qui permet de résoudre d'une manière quasi-optimale le problème d'allocation. Cette méthode est pseudo-polynomiale alors que le problème d'allocation est NP-complet même à l'intérieur d'un « basic block ». Dans la deuxième partie de la thèse nous nous intéressons au problème de l'allocation de mémoires locales. Au vu des dernières avancées dans le domaine de l'allocation de registres, nous étudions dans quelle mesure le problème d'allocation pourrait être séparé de celui de l'assignation dans le contexte des mémoires locales. Dans un premier temps nous validons expérimentalement que les problèmes d'allocation et d'assignation peuvent être résolus séparément. Ensuite, nous procédons à une étude plus théorique d'une approche découplée de l'allocation de mémoires locales. Cela permet d'introduire de nouveaux résultats sur le « submarine-building problem », une variante du « ship-building problem », que nous avons défini. L'un de ces résultats met en évidence pour la première fois une différence de complexité (P vs. NP-complet) entre les graphes d'intervalles et les graphes d'intervalles unitaires. Dans la troisième partie de la thèse nous proposons une nouvelle heuristique, appelée « clustering allocator » fondée sur la construction de sous-graphes stables d'un graphe d'interférence, permettant de découpler aussi bien le problème d'allocation pour les registres que pour les mémoires locales. Cette nouvelle heuristique se veut le pont qui permettra de réconcilier les problèmes d'allocations de registres et de mémoires locales

Split Register Allocation: Linear Complexity Without the Performance Penalty

International audienceJust-in-time compilers are becoming ubiquitous, spurring the design of more efficient algorithms and more elaborate intermediate representations. They rely on continuous, feedback-directed (re-)compilation frameworks to adaptively select a limited set of hot functions for aggressive optimization. To date, (quasi-)linear complexity has remained a driving force in the design of just-in-time optimizers. This paper describes a \emph{split register allocator} showing that linear complexity does not imply reduced code quality. We present a \emph{split compiler} design, where more expensive ahead-of-time analyses guide lightweight just-in-time optimizations. A split register allocator can be very aggressive in its offline stage, producing a semantic summary through bytecode annotations that can be processed by a lightweight online stage. The challenges are fourfold: (sub-)linear-size annotation, linear-time online processing, minimal loss of code quality, and portability of the annotation. We propose a split register allocator meeting these challenges. A compact annotation derived from an optimal integer linear program (ILP) formulation of register allocation drives a linear-time algorithm near optimality. We study the robustness of this algorithm to variations in the number of physical registers. Our method is implemented in JikesRVM and evaluated on standard benchmarks

Concepts fondamentaux des changements climatiques, état des connaissances et impacts sur la pêche au Sénégal

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Using UAV Borne, Multi-Spectral Imaging for the Field Phenotyping of Shoot Biomass, Leaf Area Index and Height of West African Sorghum Varieties under Two Contrasted Water Conditions

International audienceMeeting food demand for the growing population will require an increase to crop production despite climate changes and, more particularly, severe drought episodes. Sorghum is one of the cereals most adapted to drought that feed millions of people around the world. Valorizing its genetic diversity for crop improvement can benefit from extensive phenotyping. The current methods to evaluate plant biomass, leaves area and plants height involve destructive sampling and are not practical in breeding. Phenotyping relying on drone based imagery is a powerful approach in this context. The objective of this study was to develop and validate a high throughput field phenotyping method of sorghum growth traits under contrasted water conditions relying on drone based imagery. Experiments were conducted in Bambey (Senegal) in 2018 and 2019, to test the ability of multi-spectral sensing technologies on-board a UAV platform to calculate various vegetation indices to estimate plants characteristics. In total, ten (10) contrasted varieties of West African sorghum collection were selected and arranged in a randomized complete block design with three (3) replicates and two (2) water treatments (well-watered and drought stress). This study focused on plant biomass, leaf area index (LAI) and the plant height that were measured weekly from emergence to maturity. Drone flights were performed just before each destructive sampling and images were taken by multi-spectral and visible cameras. UAV-derived vegetation indices exhibited their capacity of estimating LAI and biomass in the 2018 calibration data set, in particular: normalized difference vegetative index (NDVI), corrected transformed vegetation index (CTVI), seconded modified soil-adjusted vegetation index (MSAVI2), green normalize difference vegetation index (GNDVI), and simple ratio (SR) (r2 of 0.8 and 0.6 for LAI and biomass, respectively). Developed models were validated with 2019 data, showing a good performance (r2 of 0.92 and 0.91 for LAI and biomass accordingly). Results were also promising regarding plant height estimation (RMSE = 9.88 cm). Regression plots between the image-based estimation and the measured plant height showed a r2 of 0.83. The validation results were similar between water treatments. This study is the first successful application of drone based imagery for phenotyping sorghum growth and development in a West African context characterized by severe drought occurrence. The developed approach could be used as a decision support tool for breeding programs and as a tool to increase the throughput of sorghum genetic diversity characterization for adaptive traits