Filippo Gioachin

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Cosmological simulators are an important component in the study of the formation of galaxies and large scale structures, and can help answer many important questions about the Universe. Despite their utility, existing parallel simulators do not scale effectively on modern machines containing thousands of processors. In this paper we present ChaNGa, a(More)
This paper focuses on the use of GPGPU-based clusters for hierarchical N-body simulations. Whereas the behavior of these hierarchical methods has been studied in the past on CPU-based architectures, we investigate key performance issues in the context of clusters of GPUs. These include kernel organization and efficiency, the balance between tree traversal(More)
Cloud computing is emerging as a promising alternative to supercomputers for some high-performance computing (HPC) applications. With cloud as an additional deployment option, HPC users and providers are faced with the challenges of dealing with highly heterogeneous resources, where the variability spans across a wide range of processor configurations,(More)
Cosmological simulators are currently an important component in the study of the formation of galaxies and planetary systems. However, existing simulators do not scale effectively on more recent machines containing thousands of processors. In this paper, we introduce a new parallel simulator called ParallelGravity. This simulator is based on the Charm++(More)
Cloud computing is emerging as an alternative to supercomputers for some of the high-performance computing (HPC) applications that do not require a fully dedicated machine. With cloud as an additional deployment option, HPC users are faced with the challenges of dealing with highly heterogeneous resources, where the variability spans across a wide range of(More)
A range of tools, from parallel debuggers to performance analysis/visualization to simulation visualizers, can benefit from interaction with a running parallel application. To be effective, this live interaction needs to be highly scalable. Such scalability for parallel applications is available in the form of the Charm++/AMPI runtime system. Charm++ is an(More)
Emergency alert systems typically demand push notification because of the infrequency of such events and the urgency of notifying parties about them. However, push notification systems like email have many limitations, such as susceptibility to SPAM and security vulnerabilities. We explore the idea of basing health alerts on RSS feeds, which are a(More)
Clusters of multicore nodes have become the most popular option for new HPC systems due to their scalability and performance/cost ratio. The complexity of programming multicore systems underscores the need for powerful and efficient runtime systems that manage resources such as threads and communication sub-systems on behalf of the applications. In this(More)
This paper presents a scheme to optimize the mapping of HPC applications to a set of <i>hybrid</i> dedicated and cloud resources. First, we characterize application performance on dedicated clusters and cloud to obtain application signatures. Then, we propose an algorithm to match these signatures to resources such that performance is maximized and cost is(More)