The nanoPU is a new networking-optimized CPU designed to minimize tail latency for RPCs. By bypassing the cache and memory hierarchy, the nanoPU directly places arriving messages into the CPU register file. The wire-to-wire latency through the application is just 65ns, about 13x faster than the current state-of-the-art. The nanoPU moves key functions from software to hardware: reliable network transport, congestion control, core selection, and thread scheduling. It also supports a unique feature to bound the tail latency experienced by high-priority applications. Our prototype nanoPU is based on a modified RISC-V CPU; we evaluate its performance using cycle-accurate simulations of 324 cores on AWS FPGAs, including real applications (MICA and chain replication).
@article{arxiv.2010.12114,
title = {The nanoPU: Redesigning the CPU-Network Interface to Minimize RPC Tail Latency},
author = {Stephen Ibanez and Alex Mallery and Serhat Arslan and Theo Jepsen and Muhammad Shahbaz and Nick McKeown and Changhoon Kim},
journal= {arXiv preprint arXiv:2010.12114},
year = {2020}
}