NvAGP vs AGPGART

aminal · Posted: Mon Mar 29, 2004 10:52 pm Post subject: NvAGP vs AGPGART

hey guys - quick question;

i was going through dmesg and I noticed an alert that said 'cannot load nvagp agpgart is already loaded!' now, i know I compiled agpgart as a module, but I also chose agp support for the via chipset (which is what I have on the mobo) , which I compiled in. Now, when I do an lsmod, via_agp and agpgart are loaded, with agpgart being used by via_agp. agpgart isn't in my autoload file, so obviously it's being loaded by via_agp.

My question is: do I go back and change via agp support to a mudule as well and recompile? Is it safe? How big is the performance difference between agpgart and NvAGP anyway?

Thanks a lot.

aminal · Posted: Tue Mar 30, 2004 12:22 am Post subject:

Nobody knows, huh? :wink:

mike4148 · l33t Joined: 09 Sep 2003 Posts: 641

The performance difference varies between systems.

If I were you, here's what I would do:

1. Run a heavy-duty benchmark (i.e., not glxgears; commercial games/demos work well) under X with NvAGP set to "2" (and the agpgart and via_agp modules loaded). Be sure to run it a few times.

2. Build your kernel with NO agpgart support at all; hotplug will autoload your agpgart modules if they exist. Needless to say, boot into your newly-built kernel.

3. Run the same benchmark with NvAGP set to "1". Compare and contrast, and decide which one you want to use.

If you don't really care, I'd use nVidia's AGP, unless it did not support your chipset. In which case, I'd use agpgart. I'm assuming that nVidia's black box AGP code was tuned for their cards.

aminal · Posted: Tue Mar 30, 2004 1:06 am Post subject:

justanothergentoofanatic · Guru Joined: 29 Feb 2004 Posts: 337

The kernel has a built-in module autoloader that will load modules as needed. Hotplug is not necessary to load the AGP modules.

To reiterate mike's comments: If you want to use the nVidia AGP driver, you'll have to completely disable both DRI and AGPGART in the kernel. Compiling them as modules and unloading the modules is not sufficent.

In my experience, the nVidia driver is much more stable than the xfree one. However, I have an nforce motherboard.

-Mike

Suicidal · l33t Joined: 30 Jul 2003 Posts: 959 Location: /dev/null

I have an old i815 board with a GF ti 200 and a work computer wit an i850 they both perform much faster via Nvidia's agp support vs xfree's.

I have used glxgears, games-action/armagetron, games-fps/ut2003 The nvidia drivers are at least 30% faster in my case.