What is 'Redwood' option under 'OpenCL'?

[bill2reg]

When I choose 'Experimental' as the render option in Cycles and go to the user preferences, 'system' tab, the choices are 'None > CPU' or 'OpenCL > 'Redwood'. My system has and AMD ATI Radeon graphics card. I have chosen this option, but there were two things I noticed. First, the rendering time using the GPU was actually longer that it was with the CPU, and there was no color in the final render, only shades of gray, as if with no lighting.

I wonder if the 'Redwood' setting is even using the GPU, or is it using the CPU anyway, but somehow affecting the way Cycles is working, to render withour color? I couldn't find any clear answer about what this 'Redwood' option is.

[bill2reg]

Using Blender 2.63 as of last week.

[stiv]

the rendering time using the GPU was actually longer that it was with the CPU

Testimony to the power of your graphics card?

[bill2reg]

Stiv, as I said, I don't even know for sure if the graphics card IS being used, since I can't find a definite answer about what the "Redwood" option is actually doing. That's the reason I posted the question.