Coupling regular topologies with optimized routing algorithms is key in pushing the performance of interconnection networks of HPC systems. In this paper we present Dmodc, a fast deterministic routing algorithm for Parallel Generalized Fat-Trees (PGFTs) which minimizes congestion risk even under massive topology degradation caused by equipment failure. It applies a modulo-based computation of forwarding tables among switches closer to the destination, using only knowledge of subtrees for pre-modulo division. Dmodc allows complete rerouting of topologies with tens of thousands of nodes in less than a second, which greatly helps centralized fabric management react to faults with high-quality routing tables and no impact to running applications in current and future very large-scale HPC clusters. We compare Dmodc against routing algorithms available in the InfiniBand control software (OpenSM) first for routing execution time to show feasibility at scale, and then for congestion risk under degradation to demonstrate robustness. The latter comparison is done using static analysis of routing tables under random permutation (RP), shift permutation (SP) and all-to-all (A2A) traffic patterns. Results for Dmodc show A2A and RP congestion risks similar under heavy degradation as the most stable algorithms compared, and near-optimal SP congestion risk up to 1% of random degradation.

The main goal of this Chapter is devoted to provide all the fundamental basis related to the involved technological issues relative to the single-sensor imaging devices. A rough understanding of the overall ingredients of a typical imaging pipeline is important also to consider the performance of any imaging devices, from low to high level, as the result of several components that run together to compose a complex system. The final image/video quality is the result of a certain number of design choices, that involve, in almost all cases, all aspects of the hardware and software technology. As briefly stated in the preface, the book aims to cover all aspects of algorithms and methods for the processing of digital images acquired by imaging consumer devices. More specifically, we will introduce the fundamental basis of specific processing into CFA (Color Filter Array) domain such as demosaicing, enhancement, denoising, compression together with ad-hoc matrixing, color balancing and exposure correction techniques devoted to preprocess input data coming from the sensor. We conclude the Chapter just including some related issues related to the intrinsic modularity of the pipeline together with a brief description of the hardware/software partitioning design phase.

Coupling regular topologies with optimised routing algorithms is key in pushing the performance of interconnection networks of supercomputers. In this paper we present Dmodc, a fast deterministic routing algorithm for Parallel Generalised Fat-Trees (PGFTs) which minimises congestion risk even under massive network degradation caused by equipment failure. Dmodc computes forwarding tables with a closed-form arithmetic formula by relying on a fast preprocessing phase. This allows complete re-routing of networks with tens of thousands of nodes in less than a second. In turn, this greatly helps centralised fabric management react to faults with high-quality routing tables and no impact to running applications in current and future very large-scale HPC clusters.

The advent of the multicore era led to the duplication of functional units through an increasing number of cores. To exploit those processors, a shared-memory parallel programming model is one possible direction. Thus, OpenMP is a good candidate to enable different paradigms: data parallelism (including loop-based directives) and control parallelism, through the notion of tasks with dependencies. But this is the programmer responsibility to ensure that data dependencies are complete such as no data races may happen. It might be complex to guarantee that no issue will occur and that all dependencies have been correctly expressed in the context of nested tasks. This paper proposes an algorithm to detect the data dependencies that might be missing on the OpenMP task clauses between tasks that have been generated by different parents. This approach is implemented inside a tool relying on the OMPT interface.