Okay, here are the results so far of my quest for fast 2D (DMA) system to video memory transfers with X on linux. The options seem to be: - NVidia's closed source drivers in combination with fast GeForces. These drivers actually use AGP DMA transfers for the various PutImage calls. However, it looks like they need fairly fast AGP (4x or more) and video card (GF2 or more) to see significant improvements over the XFree nv driver. My setup (P4 + i845E + GF2GTS, at AGP4x) sees speedups in the range of 25 - 100% with the nvidia driver, for image sizes of 1 - 3 MB. More recent (GF4) video cards are reportedly faster at this. Note that DMA is not done in the background; the X server uses 100% CPU during the transfer. - Support for the i845G seems to be getting there in XFree (4.3.0). I haven't tried it yet, but transfers to video memory should be fast (sharing video and system memory). - Finally, I noticed that performance of DGA with the XFree nv driver is quite good if, and only if, the image size is relatively small (<1MB). Thanks to everyone who responded - especially Mark Vojkovich for his extremely helpful email support! - Reinoud
