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→Cache Coherence and Cache Line
Each processor has their own local cache. When data is needed, a fixed block of memory is transferred to the cache; this block is known as a cache line.
However, if they each modify their own copy, how do we know which one is correct? We can’t store all the different versions or pick a random one to be the correct version, this would create havoc in our computer systems.
The answer is we need cache coherence. '''Cache coherence''' is defined as the '''uniformity of shared resource data that ends up stored in multiple local caches'''. In other words, we must keep all the local caches synchronized. The challenge of doing so is known as the Cache Coherence Problem. To solve this problem, multi-processor systems rely on cache coherence protocols to manage and maintain the cache.
== False Sharing ==