How to compile on multiple cores using mingw insid

Question

I have a quad-core i7 CPU on my windows desktop. I am trying to get mingw32-make to compile using as many core as possible. I have added -j8 into the "Make Arguments" fields under Build Settings->Build Steps. mingw32-make seems to completely ignore the option since I don't get any speed improvement out of that. When I view the CPU usage in task manager, it stays at 13% and I only see one instance of g++ running.

Right now, rebuilding the whole project using mingw takes 3 full minutes. Rebuilding it using MSVC takes only 15 seconds.

For your information, I have enabled the precompiled header option in the project settings. That makes things a lot quicker with VC as well. But I am still yet to see the benefit of precompiled header with mingw.

Please share your comments if you have ever got mingw to compile multiple source files in parallel from QTCreator. Thanks!

Answer 1

-j is the way to go, unfortunately for me the project is so large it uses up all of my available memory and my computer freezes, so be aware of that. Brendan said there is no way to only use half your cores for example which is a pity if true.