Coherency in CHI

Advanced snoop filtering and directory-based protocols.

Snoop Filtering

In large CHI systems (e.g., 128 cores), global snooping is impossible. The **Home Node (HN-F)** uses a Snoop Filter to track exactly which Request Nodes (RN-F) have a copy of a cache line.

This ensures that snoop messages are only sent to the 2 or 3 relevant cores, saving massive amounts of power and bandwidth.

Advanced Topic: Cache Stashing
CHI allows a Master (like a Network Controller) to "Stash" data directly into a CPU's L3 or L2 cache. This reduces latency when the CPU finally needs to process the incoming packet.

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