Martin Golasowski

System and Application Scenarios for Disaster Management Processes, the Rainfall-Runoff Model Case Study

In the future, the silicon technology will continue to reduce following the Moore’s law. Device variability is going to increase due to a loss in controllability during silicon chip fabrication. Then, the mean time between failures is also going to decrease. The current methodologies based on error detection and thread re-execution (roll back) can not be enough, when the number of errors increases and arrives to a specific threshold. This dynamic scenario can be very negative if we are executing programs in HPC systems where a correct, accurate and time constrained solution is expected. The objective of this paper is to describe and analyse the needs and constraints of different applications studied in disaster management processes. These applications fall mainly in the domains of the High Performance Computing (HPC). Even if this domain can have differences in terms of computation needs, system form factor and power consumption, it nevertheless shares some commonalities.

Uncertainty modelling in Rainfall-Runoff simulations based on parallel Monte Carlo method

This article describes statistical evaluation of the computational model for precipitation forecast and proposes a method for uncertainty modelling of rainfall-runoff models in the Floreon+ system based on this evaluation. The Monte-Carlo simulation method is used for estimating possible river discharge and provides several confidence intervals that can support the decisions in operational disaster management. Experiments with other parameters of the model and their influence on final river discharge are also discussed.

Flood Prediction Model Simulation With Heterogeneous Trade-Offs In High Performance Computing Framework.

In this paper, we propose a safety-critical system with a run-time resource management that is used to operate an application for flood monitoring and prediction. This application can run with different Quality of Service (QoS) levels depending on the current hydrometeorological situation. The system operation can follow two main scenarios standard or emergency operation. The standard operation is active when no disaster occurs, but the system still executes shortterm prediction simulations and monitors the state of the river discharge and precipitation intensity. Emergency operation is active when some emergency situation is detected or predicted by the simulations. The resource allocation can either be used for decreasing power consumption and minimizing needed resources in standard operation, or for increasing the precision and decreasing response times in emergency operation. This paper shows that it is possible to describe different optimal points at design time and use them to adapt to the current quality of service requirements during run-time.

Automatic calibration of rainfall-runoff models and its parallelization strategies

For successful decision making in disaster management it is necessary to have very accurate information about disaster phenomena and its potential developmentin time. Rainfall-runoff simulations are an integral part of flood warning and decision making processes. To increase their accuracy, it is crucial to periodically updatetheir parametersin a calibration process.Since calibration is very time consuming process an HPC facility is convenient tool for its speed-up. However, required speed-up can be achieved only avoiding any human-computer interaction in so-called automatic calibration.In order to compare possibilities and efficiency of the automatic calibration, three different fully automatic parallel implementationstrategies were created and tested with our in-house rainfall-runoff model.

Expressing and Applying C++ Code Transformations for the HDF5 API Through a DSL

Hierarchical Data Format (HDF5) is a popular binary storage solution in high performance computing (HPC) and other scientific fields. It has bindings for many popular programming languages, including C++, which is widely used in the HPC field. Its C++ API requires mapping of the native C++ data types to types native to the HDF5 API. This task can be error prone, especially when working with complex data structures, which are usually stored using HDF5 compound data types. Due to the lack of a comprehensive reflection mechanism in C++, the mapping code for data manipulation has to be hand-written for each compound type separately. This approach is vulnerable to bugs and mistakes, which can be eliminated by using an automated code generation phase. In this paper we present an approach implemented in the LARA language and supported by the tool Clava, which allows us to automate the generation of the HDF5 data access code for complex data structures in C++.

Performance Evaluation of Probabilistic Time-Dependent Travel Time Computation

Computational performance of route planning algorithms has become increasingly important in recent real navigation applications with many simultaneous route requests. Navigation applications should recommend routes as quickly as possible and preferably with some added value. This paper presents a performance evaluation of the main part of probabilistic time-dependent route planning algorithm. The main part of the algorithm computes the full probability distribution of travel time on routes with Monte Carlo simulation. Experiments show the performance of the algorithm and suggest real possibilities of use in modern navigation applications.

Autotuning and adaptivity in energy efficient HPC systems: the ANTAREX toolbox

Designing and optimizing applications for energy-efficient High Performance Computing systems up to the Exascale era is an extremely challenging problem. This paper presents the toolbox developed in the ANTAREX European project for autotuning and adaptivity in energy efficient HPC systems. In particular, the modules of the ANTAREX toolbox are described as well as some preliminary results of the application to two target use cases. 1

Using an adaptive and time predictable runtime system for power-aware HPC-oriented applications

An increasing number of High-Performance Applications demand some form of time predictability, in particular in scenarios where correctness depends on both performance and timing requirements, and the failure to meet either of them is critical. Consequently, a more predictable HPC system is required, particularly for an emerging class of adaptive real-time HPC applications. Here we present our runtime approach which produces the results in the predictable time with the minimized allocation of hardware resources. The paper describes the advantages in terms of execution time reliability and the trade-offs regarding power/energy consumption and temperature of the system compared with the current GNU/Linux governors.

Framework for scheduling and resource management in time-constrained HPC application

The silicon technology continues reducing scale following the Moore’s law. Device variability increases due to a lost in controllability during silicon chip fabrication. The current methodologies based on error detection and thread re-execution (roll back) cannot be enough, when the number of errors increase and arrive to a threshold. This dynamic scenario can be very negative if we are executing programs in HPC systems where a correct, accurate and time constraints solution is expected. The objective of the paper is to show preliminary results of Barbeque OpenSource Project (BOSP) and its potential use in HPC systems.

Floreon+ Modules: A Real-World HARPA Application in the High-End HPC System Domain

This chapter is centered around uncertainty computation with on-demand resource allocation for run-off prediction in a High-Performance Computer environment. Our research stands on a runtime operating system that automatically adapts resource allocation with the computation to provide precise outcomes before the time deadline. In our case, input data comes from several gauging stations, and when newly updated data arrives, models must be re-executed to provide accurate results immediately. Since the models run continuously (24/7), their computational demand is different during various hydrological events (e.g. periods with heavy rain and without any rain) and therefore computational resources have to be balanced according to the event severity. Although these kinds of models should run constantly, they are very computationally demanding during discrete periods of time, for example in the case of heavy rain. Then, the accuracy of the results must be as close as possible to reality. The work relies on the HARPA runtime resource manager that adapts resource allocation to the runtime-variable performance demand of applications. The resource assignment is temperature-aware: the application execution is dynamically migrated to the coolest cores, and this has a positive impact on the system reliability.