[ut2004] Trying to track down a performance bottleneck

Ian Hastie ianh at iahastie.clara.net
Wed Jun 9 13:20:13 EDT 2004

On Wednesday 09 Jun 2004 09:54, Luke Bigum wrote:
> On Wed, 9 Jun 2004 18:26, Scott Robinson wrote:
> > Have you added the options:
> >
> > options nvidia NVreg_EnableAGPFW=1 NVreg_EnableAGPSBA=1
> > NVreg_ReqAGPRate=8
> >
> > To your module configuration?
> No it wasn't. I have since added it but see no difference.
> cat /proc/drivers/nvidia/agp/status tells me AGP is disabled, even though
> I've fixed my kernel so that AGPART seems to be working.
> 'dmesg | grep agp' gives
> Linux agpgart interface v0.100 (c) Dave Jones
> agpgart: Detected AGP bridge 0
> agpgart: Maximum main memory to use for agp memory: 816M
> agpgart: AGP aperture is 256M @ 0xe0000000
> Am tracking down the best way to get AGP support for my VIA K8T800 chipset
> at the moment.

For the 2.6 kernels you need to use the amd64_agp.ko kernel module or have it 
compiled in.  The motherboard chipset on AMD64 bit systems only acts as a 
tunnel between the GART, on the CPU, and the physical AGP bus itself.  Then 
you need to tell the NVIDIA driver to use it rather than NvAGP which it does 
by default.  To do that you need to have the following line in your X config 
file Device section for your graphics card.

Option     "NvAGP"             "3"

This specific setting will try AGPGART and fall through to NvAGP if it needs 

> > > I have:
> > > Athlon64 3200+ (running as an AthlonXP)

Not really.  Because of the underlying architecture improvements the Athlon 64 
is faster, clock for clock, than an Athlon XP even in 32 bit mode.  It also 
supports SSE2 which the Athlon XP doesn't.


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