RV710 much slower on kms

[Dave Airlie]

On Sat, Dec 26, 2009 at 2:54 AM, Dr. David Alan Gilbert
<dave at treblig.org> wrote:
> Hi,
>  I'm running an RV710 on 2.6.33-rc2 and it works great without KMS;
> but with KMS it's a lot slower and I can see X eating a lot of CPU
> even when not much is happening.
>
>  It seems to start off OK, but then really starts eating it - I've
> seen X eating ~80% of one core running a simple flash game, and even
> saw the system when apparently idle eating over 50% of one core
> (but that stopped after reboot). The CPU is an i7-860.
> The time in that last idle case all seems to be userspace time,
> strace'ing X shows it was doing a lot of ioctl's to the DRI.
>
>  I'm running X 1.6.5 (I'm using the Ubuntu xorg-edgers packages for everything
> other than the kernel; I'm on Ubuntu 9.10 as the base system).
>
> I've included two xorg.0.log's; one with kms and one without.
>
> If you need any other debug, just ask.

Get a new X server really is the answer, 1.7.x has improved EXA
mainly to deal with kms drivers. radeon KMS on pre-1.7 servers isn't
something I'd forsee a distro wanting to ship.

Dave.