Why can't cache can be made as large as the device for which it is caching?

Answer 1

Cache cannot be made as large as the device it serves because of cost, speed, and efficiency considerations. Larger caches require more expensive memory technology, which can significantly increase the overall cost of the device. Additionally, as cache size increases, the access time can also increase, negating the speed advantages of caching. Finally, diminishing returns occur with larger caches, as the likelihood of retrieving data from a larger cache decreases after a certain point due to the nature of data access patterns.