How many levels of cache do modern processors typically have?

• A. Two
• B. Three
• C. Four
• D. Five

Answer: (B)

Cache depth in modern CPUs is all about balancing speed and capacity. The closest cache is tiny but incredibly fast, so it serves the most frequently used data and instructions. The next level is larger and a bit slower, catching more stuff with still-good speed. The largest level is even bigger and slower, but it’s shared among cores to reduce misses that would force expensive main memory access. This three-level structure—small, ultra-fast L1; larger L2; and the biggest shared L3—is the typical setup because it offers fast access most of the time while providing enough capacity to keep the CPU fed without constantly reaching for main memory. Some designs might skip one level or add an extra, but three levels is the standard in mainstream processors.