Issue with Thread.SetAffinity and Threading via XNA on the Xbox 360

Question

So I developed a very efficient collision detection system, but the problem is that it still cannot run on the main thread since it's too damn slow.

I tried setting up some threading, and if the thread ends, another thread is created.

if (doneCollisions)
            {
                PopulateGrid();
            }


            if (doneCollisions)
            {
                Thread thread = new Thread(new ThreadStart(CheckCollisionsGrid));

                thread.Start();

            }

void CheckCollisionsGrid()
{
Thread.CurrentThread.SetProcessorAffinity(3);
            doneCollisions = false;
            //Increments through all the grids.
.
.
.
doneCollisions = true;
}

Now I noticed some odd behaviour when debugging. When I called Thread.SetAffinity, it sort of jumped back to it over and over once or twice before finally starting to actually check the collisions.

And now my collisions are delayed by 5-10 seconds...

If anyone has insight please input some here.

Answer 1

The XBOX 360 has 3 cores with 2 hardware threads per core, producing a total of 6 hardware threads. Threads 0 and 2 are reserved by the XNA Framework, leaving 1, 3, 4 and 5 for you to use.

As for the question, why are you creating a new thread after checking for collisions, to do exactly the same all over again? If you need to repeat the collision checking in a thread, simply put it inside a while(true) loop to keep it going.