Modeling the Scalability of the EuroExa Reconfigurable Accelerators - Preliminary Results - Invited Paper.

Current technology and application trends push for both performance and power efficiency. EuroEXA is a project that tries to achieve these goals and push its performance to exascale performance. Towards this objective, EuroEXA node integrate reconfigurable (FPGA) accelerators to offload computational intensive workloads. To fully utilize the FPGA's resource pool, multiple accelerators must be instantiated. System design and dimensioning requires an early performance estimation to evaluate different design options, including using larger FPGA devices, instantiating larger number of accelerator instances, etc. In this paper, we present the preliminary results of modeling the scalability of EuroEXA reconfigurable accelerators in the FPGA fabric. We start by using simple equations to bound the total number of kernels that can work in parallel depending on the available memory channels and reconfigurable resources. Then, we use a 2nd degree polynomial model to predict the performance benefits of instantiating multiple replicated kernels in a FPGA. The model suggests whether the switching to another larger FPGA is advantageous choice in terms of performance. We verify our results using micro-benchmarks on two state-of-the-art FPGAs; AlveoU50 and AlveoU280.