/MP doesn't enable OpenMP support in VS2012

Question

I have this code in visual c++ 2012:

void Run()
{
    #pragma omp parallel for
    for(int imageNo=0;imageNo<4;imageNo++)
    {
        RunForOneImage(imageNo, Data[imageNo],
                       width, height,
                       OutputWidth, OutputHeight);  
    }
}

All variables in RunForOneImage are local variables and it doesn't use any global or class member variables.

When run it, I can see that only one core became busy and other core are idle.

Why this is not running in parallel?

I selected multi processor option in visual studio (/MP). Is there any other option that I should select?

Answer 1

The /MP option means that the compilation will run on multiple processors, it's purpose is to "reduce the total time to compile the source files" .

It has nothing to do with OpenMP API . To enable OpenMP support, there's an /openmp option (in the documentation you'll also find an example and the description of how to enable OpenMP support).

Answer 2

只需转到“项目属性”->“ C / C ++”->“语言”->“打开MP支持”，然后将其切换为“是”即可。