average memory access time
How long a memory access takes on average, counting the fast hits and the slow misses: hit time plus miss rate times miss penalty.
Average memory access time is AMAT = hit time + miss rate × miss penalty, applied recursively in a multi-level hierarchy (the L1 miss penalty is the AMAT of L2, and so on).
Examples
Hit time 1 cycle, miss rate 5% and miss penalty 100 cycles give AMAT = 1 + 0.05 × 100 = 6 cycles.
See also