표준 모드를 지원하는 5Q MPI 하드웨어 유닛 설계

The Complex neuronal network models require support from simulation environment for efficient network simulations. To compute the models increasing complexity necessitated the efforts to parallelize the NEURON simulation environment. The computational neuroscientists have extended NEURON by dividing the equations for its subnet among multiple processors for increasing the competence of hardware. For spiking neuronal networks inter-processor spikes exchange consume significant portion of overall simulation time on parallel machines. In NEURON Message Passing Interface (MPI) is used for inter processor spikes exchange, MPI_Allgather collective operation is used for spikes exchange generated after each interval across distributed memory systems. However, as the number of processors become larger and larger MPI_Allgather method become bottleneck and needs efficient exchange method to reduce the spike exchange time. This work has improved MPI_Allgather method to Remote Memory Access (RMA) based on MPI-3.0 for NEURON simulation environment, MPI based on RMA provides significant advantages through increased communication concurrency in consequence enhances efficiency of NEURON and scaling the overall run time for the simulation of large network models.1

Parallel and distributed computing have enabled development of much more scalable software. However, developing concurrent software requires the programmer to be aware of nondeterminism, data races, and deadlocks. MPI (message passing interface) is a popular standard for writing message-oriented distributed applications. Some messages in MPI systems can be processed by one of the many machines and in many possible orders. This non-determinism can affect the result of an MPI application. The alternate results may or may not be correct. To verify MPI applications, we need to check all these possible orderings and use an application specific oracle to decide if these orderings give correct output.MPJ Express is an open source Java implementation of the MPI standard. Model checking of MPI Java programs is a challenging task due to their parallel nature. We developed a Java based model of MPJ Express, where processes are modeled as threads, and which can run unmodified MPI Java programs on a single system. This model enabled us to adapt the Java PathFinder explicit state software model checker (JPF) using a custom listener to verify our model running real MPI Java programs. The evaluation of our approach shows that model checking reveals incorrect system behavior that results in very intricate message orderings.

High Performance Computing (HPC) applications commonly use Message Passing Interface (MPI) to scale complex workloads on distributed memory architectures, while Graphical User Interface (GUI) is the primary basis for pre-processing and post-processing. Containerization enables portability and reproducibility for applications. Docker is a widely used containerization platform but cannot be easily adopted in secure HPC environments due to the need for root privileges to run Docker containers and the ensuing security issues, as well as the lack of native support for Message Passing Interface (MPI) and HPC workload managers. In addition to offering portability and reproducibility to scientific computing, Singularity and Sarus are container runtimes that enable containers to run on HPC with user credentials by removing security concerns and allowing reuse of Docker containers without any changes. This work presents approaches to creating and running MPI and GUI applications in an isolated container environment on HPC in the cloud. We provide performance evaluation of application containers transformed from Docker to Singularity and Sarus in the context of native on HPC in the cloud.

Chapter 8 - The Essential MPI

Large-scale parallel lattice Boltzmann–cellular automaton model of two-dimensional dendritic growth

Summary The hybrid MPI-OpenMP model is a natural parallel programming paradigm for emerging parallel architectures that are based on symmetric multiprocessor (SMP) clusters. This paper presents a hybrid implementation adapted for an implicit finite-element code developed for groundwater transport simulations. The original code was parallelized for distributed memory architectures using MPI (Message Passing Interface) using a domain decomposition strategy. OpenMP directives were then added to the code (a straightforward loop-level implementation) to use multiple threads within each MPI process. To improve the OpenMP performance, several loop modifications were adopted. The parallel performance results are compared for four modern parallel architectures. The results show that for most of the cases tested, the pure MPI approach outperforms the hybrid model. The exceptions to this observation were mainly due to a limitation in the MPI library implementation on one of the architectures. A general conclusion is that while the hybrid model is a promising approach for SMP cluster architectures, at the time of this writing, the payoff may not be justified for converting all existing MPI codes to hybrid codes. However, improvements in OpenMP compilers combined with potential MPI limitations in SMP nodes may make the hybrid approach more attractive for a broader set of applications in the future.

An efficient parallel algorithm for a new permutation generation method is presented. The crucial task in our permutation generation algorithm is starter sets generation where listing n! permutation is dependent on starter sets. Thus the task of starter sets generation is partitioned. However the parallel algorithm with 12 initial starter sets is less efficient when numbers of processors are more than seven. For increasing performance of parallel algorithm over processors, the number of initial starter sets change to 60. This parallel algorithm is directly implemented from its sequential algorithm and integrated with Message Passing Interface (MPI) libraries. The improvement of the parallel algorithm is shown better performance in terms of speedup and efficiency.

In this paper, the performance of parallel computing will be thoroughly discussed in the domain of image matching. The concept of image matching is widely used in the areas of security, medical and computer vision which require comparing two images for similarities. However, depending on the size of images, it is highly possible that the application computation cannot be handled in a single processor running a sequential algorithm. In order to overcome this limitation, parallel computing is introduced through the Message Passing Interface (MPI) library. In this project, for the comparison of two images, both images are first converted into grayscale and then are compared using the Sum of Square Differences (SSD) algorithm. Further, a parallel network of 12 processors was implemented for image matching and to calculate the performance of the SSD algorithm between both images. The performance gain of 12, 8, 4 and 2 processors was compared with the performance of a single processor. The comparison results presented a linear relationship between the performance gain and the number of processors used for execution. Hence, it proves that there are significant benefits of parallelism on SSD applications.

We describe a number of early efforts to make use of the Message-Passing Interface (MPI) standard in appli cations, based on an informal survey conducted in May-June, 1994. Rather than a definitive statement of all MPI developmental work, this paper addresses the initial successes, progress, and impressions that appli cation developers have had with MPI, according to the responses received. We summarize the important as pects of each survey response, and draw conclusions about the spread of MPI into applications. An understanding of message passing and access to the MPI standard are prerequisites for appreciating this paper. Some background material is provided to ease this requirement.

In this article, we present a parallel geometric multigrid algorithm for solving variable-coefficient elliptic partial differential equations on the unit box (with Dirichlet or Neumann boundary conditions) using highly nonuniform, octree-based, conforming finite element discretizations. Our octrees are 2:1 balanced, that is, we allow no more than one octree-level difference between octants that share a face, edge, or vertex. We describe a parallel algorithm whose input is an arbitrary 2:1 balanced fine-grid octree and whose output is a set of coarser 2:1 balanced octrees that are used in the multigrid scheme. Also, we derive matrix-free schemes for the discretized finite element operators and the intergrid transfer operations. The overall scheme is second-order accurate for sufficiently smooth right-hand sides and material properties; its complexity for nearly uniform trees is $\mathcal{O}(\frac{N}{n_p}\log\frac{N}{n_p})+\mathcal{O}(n_p\log n_p)$, where $N$ is the number of octree nodes and $n_p$ is the number of processors. Our implementation uses the Message Passing Interface standard. We present numerical experiments for the Laplace and Navier (linear elasticity) operators that demonstrate the scalability of our method. Our largest run was a highly nonuniform, 8-billion-unknown, elasticity calculation using 32,000 processors on the Teragrid system, “Ranger,” at the Texas Advanced Computing Center. Our implementation is publically available in the Dendro library, which is built on top of the PETSc library from Argonne National Laboratory.

SCALE: A hybrid MPI and multithreading based work stealing approach for massive contingency analysis in power systems

Over the past two decades, the Message Passing Interface (MPI) has evolved as the de-facto standard for programming High-Performance Computing (HPC) clusters. Its widespread utilization led to the rapid development of applications and high reusability. Meanwhile, energy- and compute-efficient devices such as Field-Programmable Gate Arrays (FPGAs) are stepping into modern data centers and HPC clusters to address the nearing end of technology scaling. This combination of traditional CPU servers and FPGA nodes leads to Reconfigurable Heterogeneous HPC (ReH 2 PC) systems that are particularly cumbersome to program because of the absence of a standard programming model. This work advocates the use of MPI to program such ReH 2 PC clusters and presents a proof of concept based on a cross-compiler, a High-Level Synthesis library, C++ library, an FPGA- and a CPU-runtime environment. The result is a one-click solution, which compiles a standard MPI application for a ReH 2 PC cluster.

In this study, a parallel extension of the Coastal and Estuarine Storm Tide (CEST) model is developed and applied to simulate the storm surge tide at South Florida induced by hurricane Irma occurred in 2017. An improvement is also made to the existing advection algorithm in CEST. This is achieved through the introduction of high-order, monotone Semi-Lagrangian advection. Distributed memory parallelization is developed via the Message Passing Interface (MPI) library. The parallel CEST model can therefore be run efficiently on machines ranging from multicore laptops to massively High Performance Computing (HPC) system. The principle advantage of being able to run the CEST model on multiple cores is that relatively low run-time is possible for real world storm surge simulations on grids with high resolution, especially in the locality where the hurricane makes landfall. The computational time is critical for storm surge model forecast to finish simulations in 30 min, and results are available to users before the arrival of the next advisory. In this study, simulation of hurricane Irma induced storm surge was approximately 22 min for 4 day simulation, with the results validated by field measurements. Further efficiency analysis reveals that the parallel CEST model can achieve linear speedup when the number of processors is not very large.

Distributed security is an evolving sub-domain of information and network security. Security applications play a serious role when data exchanging, different volumes of data should be transferred from one site to another safely and at high speed. In this paper, the parallel International Data Encryption Algorithm (IDEA) which is one of the security applications is implemented and evaluated in terms of running time, speedup, and efficiency. The parallel IDEA has been implemented using message passing interface (MPI) library, and the results have been conducted using IMAN1 Supercomputer, where a set of simulation runs carried out on different data sizes to define the best number of processor which can be used to manipulate these data sizes and to build a visualization about the processor number that can be used while the size of data increased. The experimental results show a good performance by reducing the running time, and increasing speed up of encryption and decryption processes for parallel IDEA when the number of processors ranges from 2 to 8 with achieved efficiency 97% to 83% respectively.

In this paper, a new hybrid parallelisable low order algorithm, developed by the authors for multibody dynamics analysis, is implemented numerically on a distributed memory parallel computing system. The presented implementation can currently accommodate the general spatial motion of chain systems, but key issues for its extension to general tree and closed loop systems are discussed. Explicit algebraic constraints are used to increase coarse grain parallelism, and to study the influence of the dimension of system constraint load equations on the computational efficiency of the algorithm for real parallel implementation using the Message Passing Interface (MPI). The equation formulation parallelism and linear system solution strategies which are used to reduce communication overhead are addressed. Numerical results indicate that the algorithm is scalable, that significant speed-up can be obtained, and that a quasi-logarithmic relation exists between time needed for a function call and numbers of processors used. This result agrees well with theoretical performance predictions. Numerical comparisons with results obtained from independently developed analysis codes have validated the correctness of the new hybrid parallelisable low order algorithm, and demonstrated certain computational advantages.