Many-Task Computing and Blue Waters

This report discusses many-task computing (MTC), both generically and in the context of the proposed Blue Waters systems. Blue Waters is planned to be the largest supercomputer funded by NSF when it begins production use in 2011–2012 at NCSA. The aim of this report is to inform the Blue Waters project about MTC, including understanding aspects of MTC applications that can be used to characterize the domain and understanding the implications of these aspects to middleware and policies on Blue Waters. Many MTC applications do not neatly fit the stereotypes of highperformance computing (HPC) or high-throughput computing (HTC) applications. Like HTC applications, by definition MTC applications are structured as graphs of discrete tasks, with explicit input and output dependencies forming the graph edges. However, MTC applications have significant features that distinguish them from typical HTC applications. In particular, different engineering constraints for hardware and software must be met in order to support these applications. HTC applications have traditionally run on platforms such as grids and clusters, through either workflow systems or parallel programming systems. MTC applications, in contrast, will often demand a short time to solution, may be communication intensive or data intensive, and may comprise very short tasks. Therefore, hardware and software for MTC must be engineered to support the additional communication and I/O and must minimize task dispatch overheads. The hardware of large-scale HPC systems such as Blue Waters, with its high degree of parallelism and support for intensive communication, is well suited for achieving low turnaround times with large, intensive MTC applications. However, HPC systems often lack a dynamic resourceprovisioning feature, are not ideal for task communication via the file ∗Please cite as: D. S. Katz, T. G. Armstrong, Z. Zhang, M. Wilde, and J. M. Wozniak, Many Task Computing and Blue Waters. Technical Report CI-TR-13-0911. Computation Institute, University of Chicago & Argonne National Laboratory. http://www.ci.uchicago. edu/research/papers/CI-TR-13-0911 1 ar X iv :1 20 2. 39 43 v1 [ cs .D C ] 1 7 Fe b 20 12 system, and have an I/O system that is not optimized for MTC-style applications. Hence, additional software support is likely to be required to gain full benefit from the HPC hardware.