Acer Aspire One (Intel Atom N270, 945 GSE, i686)
kernel 3.8-rc1
xf86-video-intel 2.20.17
libdrm 2.4.40
mesa 9.0.1
xserver 1.13.1

LVDS Downclocking enabled, patch applied:
[root@lamtop 1 0 tests]$ ./gem_gtt_speed 
Time to read 16k through a CPU map:              35.683µs
Time to write 16k through a CPU map:             30.951µs
Time to clear 16k through a CPU map:             19.436µs
Time to clear 16k through a cached CPU map:       1.137µs
Time to pwrite 16k through the CPU:              11.599µs
Time to pread 16k through the CPU:               11.194µs
Time to read 16k through a GTT map:             791.271µs
Time to write 16k through a GTT map:             32.875µs
Time to clear 16k through a GTT map:             25.437µs
Time to clear 16k through a cached GTT map:       6.522µs
Time to read 16k (again) through a GTT map:     726.151µs
Time to pwrite 16k through the GTT:               9.589µs
Time to pread 16k through the GTT:               22.369µs
Time to pwrite 16k through the GTT (clflush):    10.348µs
Time to pread 16k through the GTT (clflush):     23.146µs
Now partial writes.
Time to pwrite 4k through the GTT (clflush):      4.240µs
Time to pread 4k through the GTT (clflush):       7.155µs

Setting tiling mode to X
Time to read 16k through a GTT map:             728.142µs
Time to write 16k through a GTT map:             33.079µs
Time to clear 16k through a GTT map:             25.544µs
Time to clear 16k through a cached GTT map:       6.484µs
Time to read 16k (again) through a GTT map:     728.163µs

Setting tiling mode to Y
Time to read 16k through a GTT map:             832.908µs
Time to write 16k through a GTT map:             33.329µs
Time to clear 16k through a GTT map:             29.228µs
Time to clear 16k through a cached GTT map:      18.190µs
Time to read 16k (again) through a GTT map:     824.466µs