Implementation of SRCC (Sub-RTT Congestion Control) for lossless RDMA datacenter networks.
This project reproduces and evaluates the congestion control mechanism proposed in the paper:
SRCC: Sub-RTT Congestion Control for Lossless Datacenter Networks (IEEE Transactions on Industrial Informatics, 2025)
Traditional RDMA congestion control protocols such as DCQCN, HPCC, Swift, and PCN rely on RTT-scale feedback loops. Under bursty traffic conditions, congestion often develops faster than these protocols can react, leading to:
- Queue buildup
- PFC triggering
- Head-of-Line (HoL) blocking
- Throughput degradation
SRCC introduces a sub-RTT feedback mechanism that allows switches to directly notify senders about congestion before a full RTT elapses.
This repository contains an implementation of SRCC along with experiments comparing it against:
- DCQCN
- HPCC
- Swift
- PCN
- Dynamic congestion threshold calculation
- Congested flow identification
- Congestion Notification Message (CNM) generation
- Sender-side rate adjustment
- Queue monitoring
- Performance evaluation framework
- Comparison with existing RDMA congestion control schemes
The implementation includes:
- SRCC congestion detection logic
- Congestion threshold computation
- Congestion notification generation
- Sender-side rate control
- Metrics collection and visualization
Key metrics evaluated:
- Queue Length
- Pause Rate
- Throughput
SRCC reacts significantly faster to congestion, resulting in reduced queue buildup.
SRCC minimizes pause events by preventing prolonged congestion.
SRCC maintains high throughput even under bursty traffic conditions.
From the reproduced experiments:
- SRCC exhibits the lowest queue occupancy.
- Pause events are significantly reduced.
- Throughput remains close to line rate.
- Recovery after congestion is substantially faster.
- Congestion persists for a shorter duration compared to DCQCN, HPCC, Swift, and PCN.
SRCC-implementation/
│
├── src/
├── configs/
├── scripts/
├── assets/
│ ├── combined_metrics_graph.png
│ ├── queue_length_graph.png
│ ├── pause_rate_graph.png
│ └── throughput_graph.png
│
├── README.md
└── ...
Hu, Jinbin et al.
SRCC: Sub-RTT Congestion Control for Lossless Datacenter Networks
IEEE Transactions on Industrial Informatics, 2025.