Slow 2D with radeon KMS

[Damien Mir]

>
> That's it ! Thanks !
>
> I have the feeling that OSS radeon/EXA have never been improving so fast.
> Cheers from a happy end-user !
>

After my recent discoveries about KMS, I've got a few questions about what
KMS actually brings...

I read some time ago that the performance drawbacks sometimes associated
with EXA were related to the way EXA handles memory / migration. Am I
correct ?

Personally, until now I always experienced better performance with
migrationheuristic=greedy, especially when switching windows/desktop in a
non-composited environment.
This either with an old Xpress 200M or with a new HD4650.

Is KMS supposed to bring improvements about this ? For example by taking
advantage of the kernel capabilities to handle memory ? Is it related to
TTM or GEM ? What about the "unmappable" VRAM above 265M ?
Is migrationheuristic=always now supposed to be the best performing setting ?

Thanks in advance for the answers !
Dams