Introduction

Overview

PicoLink is a simplified cache-coherency protocol designed around the following principles:

• Based on TileLink, with a substantially reduced message set.

• Uses the MESI (Modified, Exclusive, Shared, Invalid) coherence model.

• Operates over two channels: A and B.

• No Probes.

• No Release.

Architectural Assumptions

The protocol assumes the following system architecture:

• CPU cores each have their own private L1 cache.

• Memory only stores clean data.

• A Coherency Manager (CM) tracks sharers and ownership.

• The topology is directory-based.

• There are no cache-to-cache transfers: memory always supplies the data payload for GrantS and GrantE.