Comment 0 for bug 521737

I am testing the Radeon open source stack with the Kubuntu Lucid (10.04) current packages. Up to 2.6.33rc6, 3D performance has been good (3D games would be playable). Starting with rc7, 3D performance is gone: 3D games get less than a frame per second, even scrolling the mouse pointer is painfully slow.

It appears that KMS was not working up until rc6, and it started working in rc7. Disabling KMS in rc7 or rc8 solves the performance issue. This could be a kernel regression, or a problem with KMS in my graphics stack. I'll post more detailed info below.

Software:

Display Server: X.Org Server 1.7.3.902 (1.7.4 RC 2)
Display Driver: radeon 6.12.99
Kernel: 2.6.33rc7 64bit (from Ubuntu's mainline ppa)

Hardware:

Radeon HD 3450
AMD Phenom X3