Work out cache miss rate impact instantly with clear inputs, formula shown and shareable results.
Average memory access time is hit time plus miss rate times miss penalty. With a 180 cycle penalty even a 3.5% miss rate adds 6.3 cycles — more than the hit time itself — which is why miss rate reduction matters far more than shaving a cycle off L1 latency.
AMAT
AMAT = hit time + miss rate x miss penalty; CPI added = miss rate x penalty x accesses per instruction
Because the penalty is two orders of magnitude larger than a hit. A 1% miss rate at 200 cycles adds 2 cycles to every access on average.
Multi-level caches, non-blocking caches with hit-under-miss, prefetching, and critical-word-first return from memory.