https://bugs.freedesktop.org/show_bug.cgi?id=84662
--- Comment #34 from Luzipher luziphermcleod@yahoo.ie --- As todays commit 7b4276d7acf2e0f77044cb50caa6ad936fa78786, "r600g,radeonsi: Always use GTT again for PIPE_USAGE_STREAM buffers", refers to this bug: The patch helps tremendously against stuttering (~0.5s pause irregularly about twice a minute) in Borderlands 2. Kernel is an unmodified agd5f 3.18-next, hardware r9 290x.
Thanks !