~/talk

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

Talkat NSDI '26 · 2026-05-04..05-06· [networking, cloud-infrastructure]
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name:Rui Ning
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name:Jiaqi Gao
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name:Kexin Liu
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name:Rui Li
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name:Chen Tian
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Claims O(1)-step convergence using end-to-end signals rather than INT, implements MIMD updates by estimating delay gradient via batch slope fitting with a constant time/space formula suitable for NICs, and coordinates separate window and rate control loops into a single multiplicative factor. Testbed shows convergence in one to two update steps; CPU overhead is slightly above DCQCN but below other competitors. Large-scale sims report 12–48% average FCT and 40–74% tail FCT improvement versus precise-INT-based CCs.

AI-written summary · about

  1. 0:00Introduction to OSCAR congestion control
  2. 1:22O(1)-step convergence need
  3. 3:36O(1)-step convergence defined
  4. 6:24Limitations of deployable solutions
  5. 7:29Multiplicative increase/decrease
  6. 9:16Delay and gradient signals
  7. 11:48OSCAR design challenges
  8. 13:11Synchronized state selection
  9. 14:35Window and rate coordination
  10. 16:03Fairness and implementation
  11. 16:24Implementation and overhead
  12. 17:26Swift vs H-TCP vs OSCAR
  13. 18:30Conclusion
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