ENERGY EFFICIENT FPGA ACCELERATORS FOR GRAPH ANALYTICS APPLICATIONS

EU   Principal Investigator: Mustafa Ozdal
  Funding: European Commission H2020-MSCA-IF
  Budget: € 145,845.60
  Duration: April 2016 - 2018

Abstract

It is reported that data centers today consume significant portion of the global electricity usage. This is expected to increase in the upcoming years as the amount of data processed in the cloud increases substantially. An effective way for data centers to achieve better performance and energy efficiency is to perform computation on specialized processing elements. Field programmable gate arrays (FPGAs) enable customization of logic after manufacturing to achieve better energy efficiency compared to general purpose processors. Today, prominent hardware and software companies are investing in data center solutions that integrate FPGAs with CPUs, and significant performance and energy improvements have been demonstrated for several data center applications. However, the main barrier for wide spread adoption of FGPAs in data centers is the cost of programming, which typically requires months of development time by hardware engineers. The objective of this project is to lower this barrier for emerging graph applications. The basic idea is to use an abstract interface that allows a domain expert to describe an application as a set of functions defined per vertex and/or edge. We have developed a customizable implementation template that allows users to specify C++ functions to describe different graph applications. The developed template hides from users many low-level implementation details such as parallelization, pipelining, synchronization, memory access optimization, race and deadlock avoidance. This helps bridge the gap between high level application descriptions and costly hardware implementations. Our experiments show that the accelerators developed using the proposed template can lead to significant energy efficiency improvements compared to multi-core server CPUs.

Work Done

An accelerator template has been developed using SystemC. A well-defined interface was developed for users to specify different graph applications using plain C++ constructs and functions. After these user-defined constructs and functions are plugged into the developed accelerator template, hardware can be generated using standard industrial flows. In experiments, several graph applications were modelled using this template, and significant reductions in power consumption were demonstrated compared to multi-core CPUs. Furthermore, collaboration with industry researchers has been set up to port the proposed accelerator template to an emerging data center platform that integrates FPGAs with CPUs. Three journal articles were published during this project and another one is in preparation. Initial results were presented in a conference, a workshop, and a seminar.

Contributions

This project has contributed to the state of the art as follows. First, an accelerator architecture is proposed that is specifically targeted at graph applications. This architecture was published in a journal article (M. Ozdal, et. al, “Graph Analytics Accelerators for Cognitive Systems”, IEEE MICRO, pp 42-51, March 2017). Second, a high-level design framework was developed to make it easy for domain experts to develop accelerators. This framework was published in another journal article (A. Ayupov, et. al, “A Template-Based Design Methodology for Graph-Parallel Hardware Accelerators”, IEEE Transactions on Computer-Aided Design of Electronic Systems, pp 420-430, May 2017). Third, this template was ported to an emerging FPGA platform. An article on this topic is currently under preparation.

Recently, there has been a shift in data center platforms towards customizable hardware such as FPGAs to achieve energy efficiency and performance improvements. However, most domain experts cannot effectively utilize these FPGAs because of the steep learning curve involved in hardware design. This project fills this gap for graph applications by making it easy to develop accelerators without hardware knowledge. This is especially helpful for small/medium companies to utilize these FPGAs without incurring high engineering costs. Also, improving FPGA utilization in data centers have the potential to significantly reduce the electricity consumption of data centers.