Given the assumptions of Practice Problem 6.18, determine the cache performance of the following code:

A. What is the total number of reads?

B. What is the total number of reads that hit in the cache?

C. What is the hit rate?

D. What would the hit rate be if the cache were twice as big?

Problem 6.18

The heart of the recent hit game SimAquarium is a tight loop that calculates the average position of 512 algae. You are evaluating its cache performance on a machine with a 2,048-byte direct-mapped data cache with 32-byte blocks (B = 32). You are given the following definitions:

You should also assume the following:

. sizeof(int) = 4.

. grid begins at memory address 0.

. The cache is initially empty.

. The only memory accesses are to the entries of the array grid. Variables i, j, total_x, and total_y are stored in registers.

Determine the cache performance for the following code:

1 23 2 3 4 5 6 for (i = 31; i >= 0; i--) { for (j = 31; j total_x + total y + } } = 0; j--) { grid [i][j].x; grid [i][j].y;