I'm working on code for packet processing device running on MIPS processor using Windriver's VxWorks Operating System. Recently I started measuring the performance of the system. I found that minor code changes not related at all to the core function is causing big performance difference. Studying it further I found that adding dummy code of few bytes on certain locations in the code may hit the performance up to 25%.
I did not find any linkage to any compiler/linker switches or to the linking order.
I know MIPS is sensitive to code alignment but I'm sure the compiler / Linker are taking care of that.
Any Idea what can cause such a big difference in performance?
Appreciate your help,