Exascale computer system design : the square kilometre array

Exascale Computer System Design: The Square Kilometre Array With each new generation, the performance of high-performance computing systems increases. In the past decade, supercomputers reached petascale performance: machines capable of processing more than 1015 floating-point operations per second (FLOPS). Today, engineers are working to conquer the next barrier: building an exascale system capable of processing more than 1018 FLOPS. A major challenge is to keep power consumption low. Petascale systems reached an energy e ciency of a few GFLOPS per watt, but it is estimated that exascale systems need to reach at least 50 GFLOPS per watt. System architects face a huge design space that is too expensive to simulate or prototype. New methodologies are needed to assess the architectural trade-o s involved in reaching the goal of building an energy-e cient exascale system in this decade. A prime example of an exascale system is the computing system required to operate the future Square Kilometre Array (SKA) radio telescope. Hundreds of thousands of antennas and thousands of dishes are constructed in two phases in the Australian and South African deserts. Two instruments are constructed in phase one: SKA1-Low and SKA1-Mid. The raw data from the receivers—nearly 150 TB/s in phase one alone—need to be processed in near real-time. Processing is performed in three steps: the station processor, the central signal processor (CSP), and the science data processor (SDP). The output is scientific data, such as sky images, for astronomers to use. The SKA is the use case for the exascale system design methodology we develop in this dissertation, with particular focus on the imaging pipeline. The first contribution of this work is an application-specific model to derive the computing requirements on the processing platform from the instrumental parameters of radio telescopes. A first-order prediction of power consumption is based on extrapolations from the TOP500 supercomputer list. An analysis of the original SKA phase-one baseline design, released by the SKA Organisation (SKAO), shows that the telescope requires a sustained computing throughput of nearly 1 EFLOPS for the SDP. We predict a power consumption of up to 120 MW in 2018. Partly based on results of this analysis, the SKAO released a revised design of the telescope to reduce the power consumption of the system. The i