Question

Consider a two-level cache hierarchy with L1 and L2 cashes. An application incurs 1.4 memory accesses per instruction on average. For this application, the miss rate of L1 cache is 0.1: the L2 cache experiences. On average, 7 misses per 1000 instructions. The miss rate of L2 expressed correct to two decimal places is ________.

Answer 1

The miss rate of the L2 cache, when calculated using the given L1 miss rate and the number of L2 misses per 1000 instructions, is 0.05 or 5.00% expressed to two decimal places.

Step-by-step explanation:

To calculate the L2 miss rate, we consider the L1 miss events that have to look into the L2 cache.

Given that the application incurs 1.4 memory accesses per instruction and the L1 miss rate is 0.1, this means that per instruction, there are 0.14 L1 cache misses (1.4 * 0.1).

The L2 cache experiences 7 misses per 1000 instructions. To find the miss rate of L2, we need to consider how many of these L1 misses would access L2.

Since L1 has 0.14 misses per instruction, for 1000 instructions, there would be 140 L1 misses (0.14 * 1000). Out of these 140 misses, L2 misses only 7 times.

Therefore, the L2 miss rate is computed as the number of L2 misses divided by the number of L1 misses, giving us 7 / 140, which equals 0.05 or 5% when expressed as a percentage.

Expressed to two decimal places, the L2 cache miss rate is 0.05 or 5.00%.