Chapter 5, Problem 5.16HW

Program Plan Intro

Given C Code:

void inner4(vec_ptr u, vec_ptr v, data_t *dest)

{

long i;

long length = vec_length(u);

data_t *udata = get_vec_start(u);

data_t *vdata = get_vec_start(v);

data_t sum = (data_t) 0;

for (i = 0; i < length; i++)

{

sum = sum + udata[i] * vdata[i];

}

*dest = sum;

}

Cycles per element (CPE):

• The CPE denotes performance of program that helps in improving code.
• It helps to understand detailed level loop performance for an iterative program.
• It is appropriate for programs that use a repetitive computation.
• The processor’s activity sequencing is controlled by a clock that provides regular signal of some frequency.

Loop unrolling:

• It denotes a program transformation that would reduce count of iterations for a loop.
• It increases count of elements computed in each iteration.
• It reduces number of operations that is not dependent to program directly.
• It reduces count of operations in critical paths of overall computations.