Understanding the formation of wait states in one-sided communication

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Due to the available concurrency in modern-day supercomputers, the complexity of developing e cient parallel applications for these platforms has grown rapidly in the last years. Many applications use message passing for parallelization, o ering three main communication paradigms: point-to-point, collective and one-sided communication. Each paradigm ts certain domains of algorithms and communication patterns best. The one-sided paradigm decouples communication and synchronization and allows a single process to de ne a complete communication. These are important features for runtime systems of new programming paradigms and state-of-the-art dynamic load-balancing strategies. In any process interaction, wait states can occur, where a process is waiting for another -idling- before it proceeds with its local computation. To eliminate such wait states, runtime and application developers alike need support in detecting and quantifying them and their root causes. However, tool support for identifying complex wait states in one-sided communication is scarce. This thesis contributes novel methods for the scalable detection and quanti cation of wait states in one-sided communication, the automatic identi cation of their root causes, and the assessment of optimization potential. The methods for wait-state detection and quanti cation, as introduced by Böohme et al. and extended by this thesis, build upon a parallel post-mortem traversal of process-local event traces, modeling an application's runtime behavior. Performance-relevant data is exchanged just in time on the recorded communication paths. Through the nature of one-sided communication, information on such communication paths is not available on all processes involved, impeding the use of this original approach for one-sided communication. The use of a novel high-level messaging framework enables the exchange of messages on the implicit communication ... ; eng