[Openchrome-users] EPIA M10K AGP performance

[Chris Hubball]

Hello,

I'm been experimenting with 2D performance on the EPIA-M10K motherboard
(CLE266).

I am measuring the time taken to perform an SDL_Flip() with a screen
resolution of 1024x768x24.  My understanding is that the flip is copying
an entire SW screen-buffer to the graphics chip and so is measuring the
graphics bus performance.  I confirmed that most of the time is due to
the copy by changing the flip to an SDL_UpdateRect() which only copies 1
pixel - this takes a few ms.

I started out using an Radeon PCI card and found that the flip took 35ms.
 This seemed slow, however understandable because the PCI bus only runs
at 32Mhz and so all data transfers are going to be slow.

Having read the motherboard datasheet, I decided to try and use the
internal CLE266 because it is in the North Bridge and so should be able
to get faster RAM access.  I built and ran unichrome with Xorg and indeed
it does report that AGP 4x is being used.

With the CLE266, the benchmark is now 25ms - much faster, but still not a
massive increase if you compare PCI to AGP4x bus speeds.

Does anybody have any advice on how I can speed up the AGP access.  I
have AGPDMA enabled in my xorg.conf - is there anything else I could try?

My system uses Debian unstable, kernel 2.6.12.2, Xorg and the unichrome
source package from http://www.csd.uwo.ca/~mfgalizi/debian.

Regards,
Chris.