5.2 Protocol¶

Accumulator compression¶

Current evidence. The thesis evaluates adaptive compression in software: native NumberGroups keep their existing representation, while each Kulisch group can choose among RAW, RANGE, INDEX, and MASK.

Protocol work. Keep numerical format and transport encoding separate:

NumberGroup.format   = KULISCH
NumberGroup.encoding = RAW | RANGE | INDEX | MASK
NumberGroup.count    = number of values

Define the encoding identifiers, supported combinations, capability negotiation, and representation of special states. The current wire descriptor and RTL parser must be updated together; the proposal above is not a claim of current RTL support.

Hardware work. Validate and decode incoming compressed groups, then select encodings and generate compressed RESULT frames. Measure parser, buffering, and packetizer costs as well as the net bandwidth saving, including descriptors and padding. Multi-switch evaluation should also measure partial traffic.

The software study is in the repository's experiments/04-experiment-exact-accumulator-compression directory.

RoCE¶

RoCE integration would bring PRISM closer to datacenter transport practice. It requires a transport mapping and compatible host integration, while retaining the collective's operation identity and numerical policy. The current protocol uses native Ethernet frames; RoCE remains an extension to develop.

Multi-switch routing and hop-by-hop reliability are covered under hardware integration.