Kevin Arthur Gomez

Exploiting free silicon for energy-efficient computing directly in NAND flash-based solid-state storage systems

Energy consumption is a fundamental issue in todays data centers as data continue growing dramatically. How to process these data in an energy-efficient way becomes more and more important. Prior work had proposed several methods to build an energy-efficient system. The basic idea is to attack the memory wall issue (i.e., the performance gap between CPUs and main memory) by moving computing closer to the data. However, these methods have not been widely adopted due to high cost and limited performance improvements. In this paper, we propose the storage processing unit (SPU) which adds computing power into NAND flash memories at standard solid-state drive (SSD) cost. By pre-processing the data using the SPU, the data that needs to be transferred to host CPUs for further processing are significantly reduced. Simulation results show that the SPU-based system can result in at least 100 times lower energy per operation than a conventional system for data-intensive applications.

Design of a storage processing unit

Researchers showed that performing computation directly on storage devices improves system performance in terms of energy consumption and processing time. For example, Riedel et al. [2] proposed an active disk which performs computation using the processor in a hard disk drive (HDD). Their experimental results showed that the active disk-based system had a factor of 2x performance improvement [2]. However, because the performance gap between the HDDs and CPUs becomes larger and larger, the active disk-based improvement is quite limited. As the role of flash memory increases in storage architectures, solid-state drives (SSDs) have gradually displaced the HDDs with higher access performance and lower power consumption. Researchers also proposed an active flash, which performs computation using a controller in the SSD [1]. However, the SSD controller needs to implement a flash translation layer to make the SSD as an emulated HDD for most operating systems. It also needs to communicate with a host interface to transfer required data. The additional computation power can be utilized is quite limited. To maximize the computation power on the SSD, we propose a processor design called storage processing unit (SPU).