How does cache coherency affect performance?

What is cache coherency and why is it important for performance?

Cache coherency refers to the consistency of data stored in local caches of a shared resource. It's crucial for performance because it ensures that all processors in a multi-core system have the most recent data, preventing delays and errors.

How does it impact multi-core processors specifically?

In multi-core processors, cache coherency helps maintain data integrity across cores. Without it, one core might work with outdated data, leading to incorrect computations and performance bottlenecks.

Can you give an example of a cache coherency protocol?

Sure! One common protocol is the MESI protocol, which stands for Modified, Exclusive, Shared, and Invalid. It helps manage the states of cache lines to ensure data consistency.

What happens if cache coherency is not maintained?

If cache coherency is not maintained, it can lead to stale data being used by processors, resulting in incorrect program behavior, data corruption, and significant performance degradation.