Placement of tasks under uncertainty on massively multicore architectures. (Placement de tâches sous incertitudes sur des architectures massivement multicoeurs)
نویسنده
چکیده
This PhD thesis is devoted to the study of combinatorial optimization problems related to massively parallel embedded architectures when taking into account uncertain data (e.g. execution time). Our focus is on chance constrained programs with the objective of nding the best solution which is feasible with a preset probability guarantee. A qualitative analysis of the uncertain data we have to treat (dependent random variables, multimodal, multidimensional, di cult to characterize through classical distributions) has lead us to design a non parametric method, the so-called robust binomial approach , valid whatever the joint distribution and which is based on robust optimization and statistical hypothesis testing. We also propose a methodology for adapting approximate algorithms for solving stochastic problems by integrating the robust binomial approach when verifying for solution feasibility. The practical relevance of our approach is validated through two problems arising in the compilation of data ow application for manycore platforms. The rst problem treats the stochastic partitioning of networks of processes on a xed set of nodes, by taking into account the load of each node and the uncertainty a ecting the weight of the processes. For nding stochastic solutions, a semi-greedy iterative algorithm has been proposed which allowed measuring the robustness and cost of the solutions with regard to those for the deterministic version of the problem. The second problem consists in studying the global placement and routing of data ow applications on a clusterized architecture. The purpose being to place the processes on clusters such that it exists a feasible routing, a GRASP heuristic has been conceived rst for the deterministic case and afterwards extended for the chance constrained variant of the problem.
منابع مشابه
Efficient locking for multicore architectures
The scalability of multithreaded applications on current multicore systems is hampered by the performance of critical sections, due in particular to the costs of access contention and cache misses. In this paper, we propose a new locking technique, Remote Core Locking (RCL) that aims to improve the performance of critical sections in legacy applications on multicore architectures. The idea of R...
متن کاملMouvement de données et placement des tâches pour les communications haute performance sur machines hiérarchiques
The emergence of multicore processors led to an increasing complexity inside the modern servers, with many cores, distributed memory banks and multiple Input/Output buses. The execution time of parallel applications depends on the efficiency of the communications between computing tasks. On recent architectures, the communication cost is largely impacted by hardware characteristics such as NUMA...
متن کاملTwo-dimensional Block Partitionings for the Parallel Sparse Cholesky Factorization : the Fan-in Method
This paper presents a discussion on 2D block mappings for the sparse Cholesky factorization on parallel MIMD architectures with distributed memory. It introduces the fan-in algorithm in a general manner and proposes several mapping strategies. The grid mapping with row balancing, inspired from Rothberg's work 21, 22] proved to be more robust than the original fan-out algorithm. Even more eecien...
متن کاملMéthodes numériques pour les plasmas sur architectures multicoeurs. (Numerical methods for plasmas on massively parallel architectures)
متن کامل
StarPU: a Runtime System for Scheduling Tasks over Accelerator-Based Multicore Machines
Multicore machines equipped with accelerators are becoming increasingly popular. The TOP500-leading RoadRunner machine is probably the most famous example of a parallel computer mixing IBM Cell Broadband Engines and AMD opteron processors. Other architectures, featuring GPU accelerators, are expected to appear in the near future. To fully tap into the potential of these hybrid machines, pure of...
متن کامل