Xserver High CPU lag with fglrx 8.9 HD3200 IGP

[gzahl]

Hey
Somebody else got a high CPU Xserver lag?
I changed my motherboard from a IGP 690G to the HD3200 and i got big algs all the time on the desktop. Seems that DRI works find, about 1500 fps at glxgears. But high CPU usage of the xserver if i move windows or i scroll.

things like this happend in the past, what helped there? Any suggestions?
Greatings
Manuel

[IBBoard]

I'm getting potentially similar behaviour. I'm running Fedora 9 with the latest (8.9) drivers built by the guys at Livna.org. Under the 2.6.25 kernels everything is smooth, but under the 2.6.26 kernels I keep getting stuttering and momentary freezing. If I've got top running at the same time I can see it's because of a spike in the XOrg load.

Anyone know what the cause might be? Or whether it's even related to the FGLRX drivers? (Since the .26 kernel works for people I'm assuming it's some issue between FGLRX and the newer kernel that's upsetting XOrg)

[gzahl]

Hi,

Well thats some pointer at least. If i'm back home (in about two weeks) i'll give the 2.6.25 kernel a try.
Greetings
Manu

[bridgman]

Not sure if there is still an issue with PAT support in the kernel and the pre-existing PAT support in fglrx -- tbere was with 8.8 IIRC -- but with 2.6.26 try the "nopat" option (turning off PAT support in the kernel) to see if that helps.

[IBBoard]

I'm just trying "nopat" (not that I know what it does) but it seems to be working so far. A couple of the top results when searching "fglrx nopat", but this blog post seems to say I've got a couple of things to fix in mtrr (whatever that is) because my values don't match.

[bridgman]

MTRRs (Memory Type & Range Registers, or something like that) and PAT (Page Attribute Table) are both related to maemory management, but MTRRs change the attributes of an entire bank of memory (potentially all of your RAM) with a single register, while PAT lets you set attributes on a single page (usually 4KB, I think) at a time.

Don't try to blindly use someone else's mtrr settings. You shouldn't normally have to change them -- they are set differently depending on amount of memory, add-in cards etc...

[IBBoard]

It wasn't blind changing (although his memory size did match mine) but it didn't seem to affect anything. All I've got in /proc/mtrr at the moment is:

reg00: base=0x00000000 (   0MB), size=2048MB: write-back, count=1

But in the "lspci -v" output I've got:

...
05:00.0 VGA compatible controller: ATI Technologies Inc R430 [Radeon X800 XL] (PCIe) (prog-if 00 [VGA controller])
	...
	Memory at e0000000 (64-bit, prefetchable) [size=256M]
...

I tried adding a line to /proc/mtrr to match that memory address, but I didn't notice a difference and since /proc it gets wiped on boot, so I'll leave it for now.