OSCAR: O(1)-Step Convergence and Readily-deployable Congestion Control#

Zhaochen Zhang, Feiyang Xue, Rui Ning (Nanjing University), Keqiang He (SJTU), Gianni Antichi (Politecnico di Milano & QMUL), et al. — Awarded Outstanding Paper

• Why: The outstanding-paper pick of the congestion-control cluster. It removes the main barrier to fast-converging CC (precise INT headers that commodity high-speed hardware can't parse) while keeping constant-time convergence.
• What: The first CC achieving O(1)-step convergence — reaching fair share in constant time regardless of network conditions — without specialized network features. In large-scale simulations with realistic workloads it beats precise-INT-based CCs by 12–48% on average FCT and 40–74% on tail FCT.
• How: Insight that delay and delay gradient carry precision comparable to INT; then three techniques: accurate low-overhead delay-gradient estimation, eliminating overreaction in MIMD updates, and coordinating independent control loops toward a single target.
• Where applicable: Commodity datacenter hardware (no INT support needed); testbed evaluation under real-world noise plus large-scale simulation. Pairs naturally with CCC above — the two papers collectively argue delay signals can replace INT for the next generation of deployable DC CC.