SORS: Why are High Performance Computing Systems still based on 1980's Architectures?

Speaker: John D. McCalpin, Barcelona Supercomputing Center. Abstract: Technology scaling and multi-core processing have led to astounding increases in the computational capabilities of microprocessors over the past decades, while the cycle time of the DRAM cells in memory systems have barely changed. Attempting to compensate for the increasing imbalance between computation and memory access costs has led to stunningly complex processor implementations with astronomical design and fabrication costs, rapidly growing power requirements, and increasingly opaque and confounding performance characteristics. While some of the increases in cost and complexity are unavoidable consequences of trying to do more complex "stuff", John provides several examples to suggest that large portions of the increased cost and complexity are due to implicit assumptions embedded in the architecture. These assumptions made sense in the technology environment of the 1980's, but do not provide the architectural features needed to enable efficient implementations with current technological balances. Examples from "vertical" data motion (up and down the cache hierarchy), "horizontal" data motion (communication and synchronization), and security are used to illustrate these principles. Further information and slides here: https://www.bsc.es/research-and-devel...