Terabyte Sort on FPGA-Accelerated Flash Storage

Abstract

Sorting is one of the most fundamental and usefulapplications in computer science, and continues to be animportant tool in analyzing large datasets. An important andchallenging subclass of sorting problems involves sorting terabytescale datasets with hundreds of billions of records. Theconventional method of sorting such large amounts of datais to distribute the data and computation over a cluster ofmachines. Such solutions can be fast but are often expensiveand power-hungry. In this paper, we propose a solution basedon flash storage connected to a collection of FPGA-based sortingaccelerators that perform large-scale merge-sort in storage. Theaccelerators include highly efficient sorting networks and mergetrees that use bitonic sorting to emit multiple sorted valuesevery cycle. We show that by appropriate use of acceleratorswe can remove all the computation bottlenecks so that the endto-endsorting performance is limited only by the flash storagebandwidth. We demonstrate that our flash-based system matchesthe performance of existing distributed-cluster solutions of muchlarger scale. More importantly, our prototype is able to showalmost twice the power efficiency compared to the existingJoulesort record holder. An optimized system with less wastefulcomponents is projected to be four times more efficient comparedto the current record holder, sorting over 200,000 records perjoule of energy.