SNIC-DSM: SmartNIC based DSM Infrastructure for Heterogeneous-ISA Machines

Heterogeneous computing is increasingly used in today's datacenters to meet the increasing computational demands of applications. Heterogeneous hardware typically includes CPUs, GPUs, ASICs, and FPGAs, among others. An important emerging trend is instructionset- architecture (ISA)-heterogeneity: high-end x86 servers with attached SmartNICs and SmartSSDs that incorporate general-purpose CPUs, typically of the RISC ISA family (e.g., ARM, RISC-V). To alleviate resource congestion on server computing nodes, application workloads can be scaled-out across server x86 CPUs and SmartNIC ARM CPUs using the distributed shared memory (DSM) abstraction. We present SNIC-DSM, a SmartNIC-based DSM infrastructure for heterogeneous ISA machines. SNIC-DSM implements a low-latency messaging layer, which enables inter-node communication across multi-ISA CPUs, and a DSM protocol processor that provides memory coherency among these nodes, both implemented in SmartNIC's FPGA logic. SNIC-DSM is reconfigurable and allows the implementation of different memory consistency protocols. Our experimental studies using compute-intensive benchmarks reveal that SNIC-DSM outperforms the state-of-the-art DSM - Popcorn Linux's software DSM - when server resource congestion is high.