Evaluating ISA support and hardware support for recursive data layouts

  • Authors:
  • Won-Taek Lim;Mithuna Thottethodi

  • Affiliations:
  • School of Electrical and Computer Engineering, Purdue University;School of Electrical and Computer Engineering, Purdue University

  • Venue:
  • HiPC'07 Proceedings of the 14th international conference on High performance computing
  • Year:
  • 2007

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Abstract

Recursive data layouts for matrices (two dimensional arrays) have been proposed to ameliorate the poor data locality caused by traditional layouts like row-major and column-major [3][12]. However, recursive data layouts require non-traditional address computation which involves bit-level manipulations that are not supported in current processors. As such, a number of software-based address computation techniques have been developed ranging from table-lookup based techniques to arithmetic-and-logic-operation based techniques. This effectively creates a tradeoff of extra computation for locality. In this paper, we design the appropriate instruction set architecture (ISA) support and hardware support to achieve address computation for recursive data layouts. Our technique captures the benefits of locality of the sophisticated data layouts while avoiding the cost of software-based address computation. Simulations reveal that our hardware approach improves the performance of matrix multiplication by factors ranging 30% to 59% over software-computed Morton-ordered indexing, especially at larger matrix sizes.