Question

Is there a way that I can (using tbb from intel) specify the number of logical processors used by their parallel loops? Like i.e. I’d like to be able to detect number of logical processors and specify how many of them I’d like to use for this task.

Answer 1

I assume you mean threads, and not processors.

int main()
{
    tbb::task_scheduler_init init(num_threads);
    ...
}

Though I still think it’s better to just let TBB handle it automatically.

EDIT: based on comments, what you want is this:

int main()
{
    struct tbb_set_affinity : public tbb::task_scheduler_observer
    {
         tbb_set_affinity(){observe(true);}
         void on_scheduler_entry(bool is_worker)
         {
            SetThreadAffinityMask(...);
         }
   } tbb_set_affinity;

   tbb::task_scheduler_init init(num_processors);
   ...
}