Performance of the c code

Question

I'm using gcc for my c programmes. How can I check which method is faster (suppose that I write a code to swap two numbers and I rewrote the same code using bit operator), is there any tool in linux to check the time,performance and space?

Answer 1

man gprof should help.

But remember, if you use profiler you should test large number of loops. And you should do it with caching effect counted so at least this should be performed on large enough memory area data with random (but the same) order. Use srandom() / random() for this.

Minimal setup:

• write 'test bed' which loops different methods through the same input (large enough loops).
• compile / link your modules with GNU compiler -pg option.
• run. You should obtain profile data file (gmon.out usually).
• man gprof -> gprof [options] -> produce reports you need -> see what you really need.