What is cache coherence in multithreading?

What is cache coherence in multithreading?

Cache coherence refers to the consistency of data stored in local caches of a shared resource in a multithreaded environment. It ensures that any changes made by one thread are visible to others, preventing stale data.

Why is cache coherence important?

It's crucial because it maintains data integrity and consistency across multiple threads, which is essential for correct program execution and performance.

What are some common cache coherence protocols?

Some common protocols include MESI (Modified, Exclusive, Shared, Invalid), MOESI, and MSI. Each has its own method for maintaining coherence.

How does cache coherence affect performance?

Cache coherence can impact performance by introducing overhead due to the need for communication between caches, but it also helps avoid errors that could lead to more significant performance issues.

Can you explain the MESI protocol?

Sure! The MESI protocol uses four states for cache lines: Modified, Exclusive, Shared, and Invalid, to manage how data is shared and updated among caches.