Tuesday, December 17, 2019

Graph Analytics Accelerator Supporting Sparse Data Representation using Crossbar Architectures

(Nagadastagiri Challapalle presenting on Wednesday, December 18, 2019 at 1:00PM ET)

Graph analytics applications are ubiquitous in this era of a connected world. These applications have very low compute to byte-transferred ratios and exhibit poor locality, which limits their computational efficiency on general purpose computing systems. Conventional hardware accelerators employ custom dataflow and memory hierarchy organization to over- come these challenges. Processing-in-memory (PIM) accelerators leverage massively parallel compute capable memory arrays to perform the in-situ operations on graph data or employ custom compute elements near the memory to leverage larger internal bandwidths. In this work, we present GaaS-X, a graph analytics accelerator that inherently supports the sparse graph data representations using an in-situ compute-enabled crossbar memory architectures. We alleviate the overheads of redundant writes, sparse to dense conversions, and redundant computations on the invalid edges that are present in the state of the art crossbar-based PIM accelerators. GaaS-X achieves 7.7× and 2.4× performance and 22× and 5.7×, energy savings, respectively, over two state-of-the-art crossbar accelerators and offers orders of magnitude improvements over GPU and CPU solutions.

Monday, December 2, 2019

MEG: A RISCV-Based System Simulation Infrastructure for Exploring Memory Optimization Using FPGAs and Hybrid Memory Cube

Emerging 3D memory technologies, such as the Hybrid Memory Cube (HMC) and High Bandwidth Memory (HBM), provide increased bandwidth and massive memory-level parallelism. Efficiently integrating emerging memories into existing systems poses new challenges and require detailed evaluation in a real computing environment. In this paper, we propose MEG, an open-source, configurable, cycle-exact, and RISC-V based full system simulation infrastructure using FPGA and HMC. MEG has three highly configurable design components: (i) an HMC adaptation module that not only enables communication between the HMC device and the processor cores but also can be extended to fit other memories (e.g., HBM, nonvolatile memory) with minimal effort, (ii) a reconfigurable memory controller along with its OS support that can be effectively leveraged by system designers to perform software-hardware co-optimization, and (iii) a performance monitor module that effectively improves the observability and debuggability of the system to guide performance optimization. We provide a prototype implementation of MEG on Xilinx VCU110 board and demonstrate its capability, fidelity, and flexibility on real-world benchmark applications. We hope that our open-source release of MEG fills a gap in the space of publicly-available FPGA-based full system simulation infrastructures specifically targeting memory system and inspires further collaborative software/hardware innovations.