how to use quad core CPU in application

Question

For using all the cores of a quad core processor what do I need to change in my code is it about adding support of multi threading or is it which is taken care by OS itself. I am having FreeBSD and language I am using is C++. I want to give complete CPU cycles to my application at least 90%.

Answer 1

You need some form of parallelism. Multi-threading or multi-processing would be fine.

Usually, multiple threads are easier to handle (since they can access shared data) than multiple processes. However, usually, multiple threads are harder to handle (since they access shared data) than multiple processes. And, yes, I wrote this deliberately.

If you have a SIMD scenario, Ninefingers' suggestion to look at OpenMP is also very good. (If you don't know what SIMD means, see Ninefingers' helpful comment below.)

Answer 2

For multi-threaded applications in C++ may I suggest Boost.Thread which should help you access the full potential of your quad-core machine.

As for changing your code, you might want to consider making things as immutable as possible. State transitions between threads are much more difficult to debug. There a plethora of things that could potentially happen in unexpected ways. See this SO thread.