I build mesa with Tom Stellard patch series "radeonsi/compute: Memory usage
fixes"

behem0th@ArchLinux ~ $ free -m && sleep 120 && free -m && sleep 720 && free -m
             total       used       free     shared    buffers     cached
Mem:         16050       3955      12094         19        124       2583
-/+ buffers/cache:       1247      14802
Swap:         5718          0       5718
             total       used       free     shared    buffers     cached
Mem:         16050       4034      12016         19        125       2655
-/+ buffers/cache:       1253      14796
Swap:         5718          0       5718
             total       used       free     shared    buffers     cached
Mem:         16050       4473      11577         19        125       3100
-/+ buffers/cache:       1247      14803
Swap:         5718          0       5718

Much better, but not perfect.