Correction to: Euro-Par 2019: Parallel Processing Workshops

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Energy-Efficient Parallel Computing: Challenges to Scaling

The energy consumption of Information and Communications Technology (ICT) presents a new grand technological challenge. The two main approaches to tackle the challenge include the development of energy-efficient hardware and software. The development of energy-efficient software employing application-level energy optimization techniques has become an important category owing to the paradigm shift in the composition of digital platforms from single-core processors to heterogeneous platforms integrating multicore CPUs and graphics processing units (GPUs). In this work, we present an overview of application-level bi-objective optimization methods for energy and performance that address two fundamental challenges, non-linearity and heterogeneity, inherent in modern high-performance computing (HPC) platforms. Applying the methods requires energy profiles of the application’s computational kernels executing on the different compute devices of the HPC platform. Therefore, we summarize the research innovations in the three mainstream component-level energy measurement methods and present their accuracy and performance tradeoffs. Finally, scaling the optimization methods for energy and performance is crucial to achieving energy efficiency objectives and meeting quality-of-service requirements in modern HPC platforms and cloud computing infrastructures. We introduce the building blocks needed to achieve this scaling and conclude with the challenges to scaling. Briefly, two significant challenges are described, namely fast optimization methods and accurate component-level energy runtime measurements, especially for components running on accelerators

OpenH: A Novel Programming Model and API for Developing Portable Parallel Programs on Heterogeneous Hybrid Servers

Heterogeneous nodes composed of a multicore CPU and accelerators are today’s norm in high-performance computing (HPC) platforms due to their superior performance and energy efficiency. Tools such as OpenCL and hybrid combinations such as OpenMP plus OpenACC are used for developing portable parallel programs for such nodes. However, these tools have some drawbacks, including a lack of compiler support for nested parallelism, performance portability, automatic heterogeneous workload distribution, user-friendly thread placement, and processor affinity essential to the portable performance of hybrid programs executing on such nodes. In this paper, we propose OpenH, a novel programming model and library API for developing portable parallel programs on heterogeneous hybrid servers composed of a multicore CPU and one or more different types of accelerators. OpenH integrates Pthreads, OpenMP, and OpenACC seamlessly to facilitate the development of hybrid parallel programs. An OpenH hybrid parallel program starts as a single main thread, creating a group of Pthreads called hosting Pthreads. A hosting Pthread then leads the execution of a software component of the program, either an OpenMP multithreaded component running on the CPU cores or an OpenACC (or OpenMP) component running on one of the accelerators of the server. The OpenH library provides API functions that allow programmers to get the configuration of the executing environment and bind the hosting Pthreads (and hence the execution of components) of the program to the CPU cores of the hybrid server to get the best performance. We illustrate the OpenH programming model and library API using two hybrid parallel applications based on matrix multiplication and 2D fast Fourier transform for the most general case of a hybrid hyperthreaded server comprising $p$ computing devices. Finally, we demonstrate the practical performance and energy consumption of OpenH for the hybrid parallel matrix multiplication application on a server comprising an Intel Icelake multicore CPU and two Nvidia A40 GPUs

Euro-Par 2019: Parallel Processing Workshops

International audienceThis book constitutes revised selected papers from the workshops held at 25th International Conference on Parallel and Distributed Computing, Euro-Par 2019, which took place in Göttingen, Germany, in August 2019.The 53 full papers and 10 poster papers presented in this volume were carefully reviewed and selected from 77 submissions.Euro-Par is an annual, international conference in Europe, covering all aspects of parallel and distributed processing. These range from theory to practice, from small to the largest parallel and distributed systems and infrastructures, from fundamental computational problems to full-edged applications, from architecture, compiler, language and interface design and implementation to tools, support infrastructures, and application performance aspects