Profiling and Optimization

Question 1

What is real time (wall clock time)?

Answer 1

Total time from start to finish

Question 2

What is CPU time?

Answer 2

Time spent executing instructions

Question 3

What is User CPU time?

Answer 3

Time spent executing in user mode (your code)

Question 4

What is System CPU time?

Answer 4

Time spent executing in kernel mode (OS code)

Question 5

What is an execution profile?

Answer 5

Locates hot spots and improves performance

Question 6

How to use gprof?

Answer 6

1. Compile and link program with -pg option to gcc
2. Run the program, creating a data file gmon.out
3. Use gprof command to produce a report