Inter-process communication in disaggregated datacenters
Amanda Carbonari · cIRcle (University of British Columbia) · 2018
Disaggregation is a promising new datacenter (DC) architecture which aims to mit- igate mounting DC costs. Disaggregated datacenters (DDCs) disaggregate tradi- tional server components into distinct resources. Disaggregation also poses an interesting paradigm shift. Namely, a DDC possesses traits akin to a distributed system, as resources no longer fate-share: a CPU can fail independently of another CPU. It is not unreasonable to assume that these disaggregated resources will still be presented to a user as a single machine. This requirement has implications for disaggregated system design. For example, what happens if a CPU fails during a remote cross-processor procedure call? This is not a new question, as distributed systems, multi-processor systems, and high performance computing (HPC) systems, have grappled with this challenge. We look at how this challenge translates to a disaggregated context, in particular, focusing on the remote procedure call (RPC) abstraction. We design a disaggregated system, Bifröst, to ensure exactly-once semantics for procedure calls under failure scenarios and provide strict memory consistency. We analyze the overhead of Bifröst compared to an equivalent RPC implementation in Thrift. Although, we find that Bifröst has a higher overhead than Thrift, its results are still promising, showing that we can achieve greater functionality than Thrift with a slightly higher overhead.