Resources

Why do CPUs have multiple cache levels?

The article explains why modern CPUs use multiple cache levels (L1, L2, L3) instead of one large cache. The key idea is that cache design involves trade-offs: smaller caches can be placed closer to the CPU core and accessed extremely quickly, while larger caches are slower but more space-efficient and can store much more data. By organizing caches in layers—small and very fast near the core, and larger but slower further away—CPUs balance speed, capacity, power consumption, and coordination between cores. The result is a hierarchy that keeps the most frequently used data close to the processor while still providing access to larger pools of memory when needed.