Cache Analysis, Continued

Memory-stall clock cycles = 0.9IC (Small) and 0.6IC (Large cache).

Substituting into the CPU time equation, letting CPI w/o stalls be C:

CPU Time = (CPU execution clock cycles + Memory-stalls clock cycles)

? Clock cycle time

Small Cache

Large Cache

CPU time

=( (C ? IC) + (0.9 ? IC) ? 15ns

= 15?C?IC + 13.5 ? IC

= (15C + 13.5)IC

CPU time

=( (C ? IC) + (0.6 ? IC) ? 18ns

= 18?C?IC + 10.8 ? IC

= (18C + 10.8)IC

For C ? 1 the smaller cache is better

Previous slide

Back to first slide

View graphic version