Towards Energy Efficient 5G vRAN Servers (RENC)#
NSDI '25 digest Program Wildcard pick 28–30 April 2025
- Authors / tier: Anuj Kalia (Microsoft); Nikita Lazarev (MIT); Leyang Xue (University of Edinburgh); Xenofon Foukas, Bozidar Radunovic (Microsoft); Francis Y. Yan (Microsoft Research and UIUC). Wildcard.
- Why: A surprising result at the intersection of real-time systems and power: you can claw back substantial CPU energy from vRAN servers despite hard sub-millisecond deadlines and black-box proprietary software. The eBPF-based slack-measurement trick is a clever pattern beyond RAN.
- What: RENC saves energy by adjusting CPU frequency in response to sub-second cellular-load variation without missing real-time deadlines.
- How: It establishes safe low-load intervals by coupling MAC-layer rate limiting to frequency changes; computes safe frequencies by measuring deadline slack in vRAN threads via Linux eBPF hooks (or minor binary rewriting of the closed vRAN binary); and handles control-driven load spikes (e.g., new-user attach). Reported up to 45% CPU power reduction (29% server-wide) on a state-of-the-art vRAN testbed.
- Where applicable: vRAN/telco edge servers; the technique is specific to real-time-deadline workloads, but the "measure slack with eBPF, then undervolt/underclock safely" idea generalizes to other latency-critical services.