Direct-Mapped Caches: Thrashing

Direct mapped cache (32 KB)

Cache line: 4 words

Location in the cache:

(memory-address) mod (cache-size)

in this case loc(A(1)) mod 32KB = loc(B(1)) mod 32KB

[because B(1) = A(1) + 8192; 8192*4B mod 32KB = 0]

2047

2048

Registers

in the CPU

COMMON //A(8192), B(8192)

DO I=1,N

PROD = PROD + A(I)*B(I)

ENDDO

Thrashing: every memory reference results in a cache miss