Performance tuning- Leveraging modern CPU branch predict mechanism.

In modern CPU the branch predictor is complicated and the deeper pipeline causing the cost of miss branch prediction higher.

How can we leveraging the modern CPU branch predictor, In [1] example code, the branch miss rate can  be reduce by just sorting input data before exciting original algorithm. 

Conclusion 

1. Adding pattern to your algorithm(sorted data).

2. Using likely()/unlikely() marco to help branch prediction more accuracy.

Reference:

1. Performance analysis in Linux

2. Code DetectiveHow to investigate LinuxPerformance Issues

3. Linux likely() unlikely() MARCO.