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-   -   Poor nvidia performance AMD64X2 4GB RAM - 64 IOMMU to blame ? (http://www.nvnews.net/vbulletin/showthread.php?t=125925)

interzoneuk 01-08-09 06:23 PM

Poor nvidia performance AMD64X2 4GB RAM - 64 IOMMU to blame ?

athlon X2 4600
motherboard : gigabyte GA-M55S-S3
2 X 2GB ram
nvidia 8500 PCI-E
Distro - ubuntu/opensuse amd64

I have recently upgraded my desktop from 1GB ram to 4GB.

Previous i was getting Aperture beyond 4GB messages, I now get

In dmesg it shows:-


Checking aperture...
No AGP bridge found
Node 0: aperture @ 20000000 size 32 MB
Aperture pointing to e820 RAM. Ignoring.
Your BIOS doesn't leave a aperture memory hole
Please enable the IOMMU option in the BIOS setup
This costs you 64 MB of RAM
Mapping aperture over 65536 KB of RAM @ 20000000
PCI: MCFG area at f0000000 reserved in E820
The memory used is not available - i.e i lose 64 MB.

I do not get this in 32bit linux using PAE - i can see all my memory.

After reading around forums I tried iommu=memaper=3 - what excatly does this do ? I noticed that Aperture was set to 256MB with this option - and I lost the 256MB..

What should I set my aperture to ? My gfx card is geforce 8500 256mb PCI-E

I also notice that if I reduce my memory to 2 or 3 GB I do not get that message.

Any sugestions ?

interzoneuk 01-09-09 06:48 AM

Re: Poor nvidia performance AMD64X2 4GB RAM - 64 IOMMU to blame ?
I have also noticed that setting iommu=memaper=0 only uses 32MB - if this setting is not needed then it should be set to this ?

Is there a way to use all my ram.

Do anyone know what it should be set to.

When using less than 4GB i can see no message regarding Aperture.

Anyone know anything that might help

(slightly confused)

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