Characteristics of adaptive runtime systems in HPC

Abstract

The phrase "Runtime System" is somewhat broad and is used with differing meanings in differing contexts. The Java runtime and most of the MPI runtimes are focused on providing mechanisms. In contrast, adaptive runtime systems emphasize strategies, in addition to providing mechanisms. This talk will look at some characteristics that make HPC RTSs adaptive. These include dynamic load balancing, exploitation of the "principle of persistence" to learn from recent data, automatic allocation to heterogeneous processors, automatic optimization of communication, application reconfiguration via control-points, automated control and optimization of temperature/power/energy/execution-time, automated tolerance of component failures so as to maintain the rate of computational progress in presence of such failures, and adapting to memory availability. The talk will examine these characteristics, and what features are necessary and/or desirable to empower the runtime system. I will illustrate it using examples from the runtime system underlying Charm++ and Adaptive MPI.