Nu: Achieving Microsecond-Scale Resource Fungibility with Logical Processes


Zhenyuan Ruan and Seo Jin Park, MIT CSAIL; Marcos K. Aguilera, VMware Research; Adam Belay, MIT CSAIL; Malte Schwarzkopf, Brown University


Datacenters waste significant compute and memory resources today because they lack resource fungibility: the ability to reassign resources quickly and without disruption. We propose logical processes, a new abstraction that splits the classic UNIX process into units of state called proclets. Proclets can be migrated quickly within datacenter racks, to provide fungibility and adapt to the memory and compute resource needs of the moment. We prototype logical processes in Nu, and use it to build three different applications: a social network application, a MapReduce system, and a scalable key-value store. We evaluate Nu with 32 servers. Our evaluation shows that Nu achieves high efficiency and fungibility: it migrates proclets in ≈100μs; under intense resource pressure, migration causes small disruptions to tail latency—the 99.9th percentile remains below or around 1ms—for a duration of 0.54–2.1s, or a modest disruption to throughput (<6%) for a duration of 24–37ms, depending on the application.

NSDI '23 Open Access Sponsored by
King Abdullah University of Science and Technology (KAUST)

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@inproceedings {285060,
author = {Zhenyuan Ruan and Seo Jin Park and Marcos K. Aguilera and Adam Belay and Malte Schwarzkopf},
title = {Nu: Achieving {Microsecond-Scale} Resource Fungibility with Logical Processes},
booktitle = {20th USENIX Symposium on Networked Systems Design and Implementation (NSDI 23)},
year = {2023},
isbn = {978-1-939133-33-5},
address = {Boston, MA},
pages = {1409--1427},
url = {},
publisher = {USENIX Association},
month = apr,
Ruan Paper (Prepublication) PDF

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