I made a small research about
radeon driver accross different distros, maybe it would help somebody:
I tried to compare differences in package configurations between Ubuntu 14.04 (which is totally good for me) and other ones. Comparing
/var/log/Xorg.0.log I found that depending on
radeon driver uses different acceleration method by default:
glamour for new version and
EXA for old ones.
EXA acceleration by default enables 'SwapbuffersWait' flag (that doesn't work with glamour):
This option controls the behavior of glXSwapBuffers and glXCopySubBufferMESA
calls by GL applications. If enabled, the calls will avoid tearing by making
sure the display scanline is outside of the area to be copied before the copy
occurs. If disabled, no scanline synchronization is performed, meaning tearing
will likely occur. Note that when enabled, this option can adversely affect
the framerate of applications that render frames at less than refresh rate.
The default value is .B on.
Switching glamour to EXA doesn't work for me, but maybe it would be worth for somebody else.
I also test old Ubuntu versions and found that I can't use even Ubuntu 14.10 (also uses EXA by default).
Maybe it's also worth to share our acceptable and unacceptable configurations. That will help us to find some common pattern(s):
Ubuntu 14.04, Unity with default options
GPU - AMD HD5450 + with open source drivers (xserver-xorg-video-radeon/radeon 7.3.0)
Kernel - 3.13.0-167-generic X86_64
Mesa - 10.1.3
Xorg server - 1.15.1
Ubuntu 14.10, Unity with default options
GPU - AMD HD5450 + with open source drivers (xserver-xorg-video-radeon/radeon 7.4.0)
Kernel - 3.16.0-23-generic X86_64
Mesa - 10.3
Xorg server - 1.16