Analytical

What is this repository for?

This repository serves the role of an analytical network backend for ASTRA-sim. It models the latency and bandwidth for various network topologies.

How to use this repository?

This repository should be cloned and used with the ASTRA-sim. Please refer to this page on how to compile and run this codebase.

Network configuration

Below are the configurations the analytical network supports.

• You may write a .json file that contains these configurations and pass it to the ASTRA-sim when you initiate a new run, by --network-configuration="/path/to/json/file.json"
• Otherwise, you can pass all the configurations separately via the command line.
• If you pass both .json file and command-line arguments, configurations set in .json get overridden by command line settings.

Available configurations

• topology-name: Set to Hierarchical.
• dimensions-count: The number of dimensions of that topology.
• topologies-per-dim: The list of topologies of each dimension. Options can be: Ring, FullyConnected, or Switch.
• dimension-type: The type of dimensions. This information is used in the cost model.
• units-count: The number of packages per each dimension. Total NPUs will be the multiplication of these numbers.
• links-count: The number of links per NPU, listed per each dimension.
• link-latency: List of link's latency (in ns) per each dimension.
• link-bandwidth: List of link's bandwidth (in GB/s) per each dimension.
• nic-latency: List of link's NIC latency (in ns) per each dimension. If the dimension is scale-up and there's no NIC, set it to 0.
• router-latency: List of router/switch latency (in ns) per each dimension. If that dimension doesn't use router/switch, set it to 0.
• hbm-latency: List of HBM's latency (in ns) per each dimension.
• hbm-bandwidth: List of High-Bandwidth Memory (HBM)'s bandwidth (in GB/s) per each dimension.
• hbm-scale: List of HBM latency scalar. This is required because one collective communication may instantiate multiple read/write operations.

Sample configuration .json file

{
  "topology-name": "Hierarchical",
  "topologies-per-dim": ["Ring", "FullyConnected", "Switch"],
  "dimension-type": ["N", "N", "P"],
  "dimensions-count": 3,
  "units-count": [2, 8, 2],
  "links-count": [2, 7, 1],
  "link-latency": [500, 500, 500],
  "link-bandwidth": [250, 25, 12.5],
  "nic-latency": [0, 0, 0],
  "router-latency": [0, 0, 0],
  "hbm-latency": [500, 500, 500],
  "hbm-bandwidth": [370, 370, 370],
  "hbm-scale": [0, 0, 0]
}

Contact

Please email William Won (william.won@gatech.edu) or Saeed Rashidi (saeed.rashidi@gatech.edu) or Tushar Krishna (tushar@ece.gatech.edu) if you have any questions.

Core Developers

• William Won (Georgia Tech)
• Saeed Rashidi (Georgia Tech)

Additional Contributors

• Sudarshan Srinivasan (Intel)
• Srinivas Sridharan (Facebook)
• Tushar Krishna (Georgia Tech)