Using Formal Grammars to Predict I-O Behaviors in HPC: the OmniscIO ApproachReport as inadecuate




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1 ENS Rennes - École normale supérieure - Rennes 2 MCS - Mathematics and Computer Science Division ANL 3 KerData - Scalable Storage for Clouds and Beyond Inria Rennes – Bretagne Atlantique , IRISA-D1 - SYSTÈMES LARGE ÉCHELLE

Abstract : The increasing gap between the computation performance of post-petascale machines and the performance of their I-O subsystem has motivated many I-O optimizations including prefetching, caching, and scheduling. In order to further improve these techniques, modeling and predicting spatial and temporal I-O patterns of HPC applications as they run has become crucial. In this paper we present Omnisc-IO, an approach that builds a grammar-based model of the I-O behavior of HPC applications and uses it to predict when future I-O operations will occur, and where and how much data will be accessed. To infer grammars, Omnisc-IO is based on StarSequitur, a novel algorithm extending Nevill-Manning-s Sequitur algorithm. Omnisc-IO is transparently integrated into the POSIX and MPI I-O stacks and does not require any modification in applications or higher-level I-O libraries. It works without any prior knowledge of the application and converges to accurate predictions of any N future I-O operations within a couple of iterations. Its implementation is efficient in both computation time and memory footprint.

Keywords : Omnisc-IO Grammar Storage I-O Prediction HPC





Author: Matthieu Dorier - Shadi Ibrahim - Gabriel Antoniu - Robert Ross -

Source: https://hal.archives-ouvertes.fr/



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