Performance Improvements for a Large-scale Geological Simulation

AbstractGeological models have been successfully used to identify and study geothermal energy resources. Many computer simulations based on these models are data-intensive applications. Large-scale geological simulations require high performance computing (HPC) techniques to run within reasonable time constraints and performance levels. One research area that can benefit greatly from HPC techniques is the modeling of heat flow beneath the Earth's surface. This paper describes the application of HPC techniques to increase the scale of research with a well-established geological model. Recently, a serial C++ application based on this geological model was ported to a parallel HPC applications using MPI. An area of focus was to increase the performance of the MPI version to enable state or regional scale simulations using large numbers of processors. First, synchronous communications among MPI processes was replaced by overlapping communication and computation (asynchronous communication). Asynchronous communication improved performance over synchronous communications by averages of 28% using 56 cores in one environment and 46% using 56 cores in another. Second, an approach for load balancing involving repartitioning the data at the start of the program resulted in runtime performance improvements of 32% using 48 cores in the first environment and 14% using 24 cores in the second when compared to the asynchronous version. An additional feature, modeling of erosion, was also added to the MPI code base. The performance improvement techniques under erosion were less effective

Energy and performance models for clocked and asynchronous communication

Journal ArticleParameterized first-order models for throughput, energy, and bandwidth are presented in this paper. Models are developed for many common pipeline methodologies, including clocked flopped, clocked time-borrowing latch protocols, asynchronous two-cycle, four-cycle, delay-insensitive, and source synchronous. The paper focuses on communication costs which have the potential to throttle design performance as scaling continues. The models can also be applied to logic. The equations share common parameters to allow apples-to-apples comparisons against different design targets and pipeline methodologies. By applying the parameters to various design targets, one can determine when unclocked communication is superior at the physical level to clocked communication in terms of energy for a given bandwidth. Comparisons between protocols at fixed targets also allow designers to understand tradeoffs between implementations that have a varying degree of timing assumptions and design requirements

Evaluating XMPP Communication in IEC 61499-based Distributed Energy Applications

The IEC 61499 reference model provides an international standard developed specifically for supporting the creation of distributed event-based automation systems. Functionality is abstracted into function blocks which can be coded graphically as well as via a text-based method. As one of the design goals was the ability to support distributed control applications, communication plays a central role in the IEC 61499 specification. In order to enable the deployment of functionality to distributed platforms, these platforms need to exchange data in a variety of protocols. IEC 61499 realizes the support of these protocols via "Service Interface Function Blocks" (SIFBs). In the context of smart grids and energy applications, IEC 61499 could play an important role, as these applications require coordinating several distributed control logics. Yet, the support of grid-related protocols is a pre-condition for a wide-spread utilization of IEC 61499. The eXtensible Messaging and Presence Protocol (XMPP) on the other hand is a well-established protocol for messaging, which has recently been adopted for smart grid communication. Thus, SIFBs for XMPP facilitate distributed control applications, which use XMPP for exchanging all control relevant data, being realized with the help of IEC 61499. This paper introduces the idea of integrating XMPP into SIFBs, demonstrates the prototypical implementation in an open source IEC 61499 platform and provides an evaluation of the feasibility of the result.Comment: 2016 IEEE 21st International Conference on Emerging Technologies and Factory Automation (ETFA

Performance Evaluation of Impulse Radio UWB Systems with Pulse-Based Polarity Randomization

In this paper, the performance of a binary phase shift keyed random time-hopping impulse radio system with pulse-based polarity randomization is analyzed. Transmission over frequency-selective channels is considered and the effects of inter-frame interference and multiple access interference on the performance of a generic Rake receiver are investigated for both synchronous and asynchronous systems. Closed form (approximate) expressions for the probability of error that are valid for various Rake combining schemes are derived. The asynchronous system is modelled as a chip-synchronous system with uniformly distributed timing jitter for the transmitted pulses of interfering users. This model allows the analytical technique developed for the synchronous case to be extended to the asynchronous case. An approximate closed-form expression for the probability of bit error, expressed in terms of the autocorrelation function of the transmitted pulse, is derived for the asynchronous case. Then, transmission over an additive white Gaussian noise channel is studied as a special case, and the effects of multiple-access interference is investigated for both synchronous and asynchronous systems. The analysis shows that the chip-synchronous assumption can result in over-estimating the error probability, and the degree of over-estimation mainly depends on the autocorrelation function of the ultra-wideband pulse and the signal-to-interference-plus-noise-ratio of the system. Simulations studies support the approximate analysis.Comment: To appear in the IEEE Transactions on Signal Processin