I have installed a clean Fedora 21 Rawhide to have the latest packages and try out latest radeonsi performance. But to my surprise the whole GNOME desktop behaved like running on vesa - redraws vere slow, firefox scrolling was very laggy, and extremetuxracer intro screen ran in something similar to 5 fps.

When I installed an older kernel 3.12, everything was very fluent and fast.

I tested:
kernel 3.12: fast drawing
kernel 3.13 rc0: slow drawing
kernel 3.13 rc7: slow drawing

No other packages were changed.

I compared dmesg and xorg logs from 3.12 and 3.13 kernels and there's no change at all, it says that glamor acceleration is enabled and everything seems OK.

$ xdriinfo 
Screen 0: radeonsi

The only weird issue I found is that glxinfo reports OpenGL 2.1 while it should report OpenGL 3.0.

$ glxinfo | grep version
server glx version string: 1.4
client glx version string: 1.4
GLX version: 1.4
OpenGL version string: 2.1 Mesa 10.0.2
OpenGL shading language version string: 1.30

I have downloaded daily compose of Ubuntu 14.04 and the problem is not present there, radeonsi performs perfectly even on kernel 3.13. The package versions in Ubuntu are almost the same as in Fedora.

I see this line in xorg log on Fedora that is not present in Ubuntu:

[    35.375] (EE) RADEON(0): Failed to set up textured video (glamor)

However, I see this line even with kernel 3.12 and there's no performance problem there.

I don't know where to look, I don't know how to debug what the problem is. I also compiled the latest xf86-video-ati from source (according to http://www.x.org/wiki/radeonBuildHowTo/ ), but no change.

This output is same as in Ubuntu:
$ LIBGL_DEBUG=verbose glxinfo > /dev/null
libGL: OpenDriver: trying /usr/lib64/dri/tls/radeonsi_dri.so
libGL: OpenDriver: trying /usr/lib64/dri/radeonsi_dri.so
libGL: driver does not expose __driDriverGetExtensions_radeonsi(): /usr/lib64/dri/radeonsi_dri.so: undefined symbol: __driDriverGetExtensions_radeonsi
libGL: Can't open configuration file /home/kparal/.drirc: No such file or directory.
libGL: Can't open configuration file /home/kparal/.drirc: No such file or directory.


Hardware and software:
01:00.0 VGA compatible controller [0300]: Advanced Micro Devices, Inc. [AMD/ATI] Curacao PRO [Radeon R9 270] [1002:6811]
kernel-3.13.0-0.rc7.git4.1.fc21.x86_64
mesa-dri-drivers-10.0.2-1.20140110.fc21.x86_64
xorg-x11-drv-ati-7.2.0-6.20131101git3b38701.fc21.x86_64
xorg-x11-glamor-0.5.1-6.20131009gitba209eee.fc21.x86_64
xorg-x11-server-Xorg-1.14.99.904-1.fc21.x86_64
llvm-3.3-4.fc21.x86_64
libdrm-2.4.50-1.fc21.x86_64

Fedora 21 daily image can be tested here:
http://kojipkgs.fedoraproject.org//work/tasks/9834/6389834/Fedora-Live-Desktop-x86_64-rawhide-20140111.iso

Ubuntu 14.04 daily image (radeonsi working well) can be tested here:
http://cdimage.ubuntu.com/daily-live/20140111/trusty-desktop-amd64.iso