What is directory-based cache coherency?

Can you explain what directory-based cache coherency is?

Sure! Directory-based cache coherency is a method used in multiprocessor systems to maintain consistency among caches. It uses a directory to track which caches have copies of a particular memory block.

How does it differ from other cache coherency protocols?

Unlike bus-based protocols that rely on broadcasting, directory-based systems use a centralized directory to manage cache states, reducing traffic and improving scalability.

What are the advantages of using directory-based cache coherency?

The main advantages include reduced bandwidth usage, better scalability for large systems, and improved performance in multi-core processors.

Are there any downsides to this approach?

Yes, some downsides include increased complexity in the directory management and potential latency in accessing the directory for cache coherence checks.