
29. Fermi Asynchronous Texture Transfers 425
Render
[0]
[1]
[2]
[3]
resultTex
Download
Figure 29.12. Render thread produces resulting image to resultTex[3] while download
thread consumes from resultTex[2].
29.5.3 Copy Engine Considerations
An OpenGL context attached to a copy engine is a fully functional GL context so that
non-DMA commands can be issued in the transfer threads. However, some of these
calls may time-slice with the rendering thread, causing us to lose parallelism. In the
event that the driver has to serialize calls between the transfer and render context, it
generates a debug message, “Pixel transfer is synchronized with 3D rendering,” which ...