I tried the apk on my galaxy nexus gsm:
Groestlhash: 10.4264 KH/s
So these initial benchmarks are getting ~10KH/thread
So would a 2 core ARM chip support 4 threads i.e. 40KH/s ?
Now I m sure we're gonna end up with much more than 10KH/s per thread.
Even at this early stage the power efficiencies are interesting. Im gonna make a big assumption but if 4 cores > 8 threads @10KH/thread = 80kH
R9290 150w ~9000 KH/s
Cortex A9 1.9W ~80 KH/s --->> so theoretically 190w required to push 8000kH/s
So even at this early stage (permitting my assumptions about multi-thread performance are true) the Cortex is only ~30% less power efficient (hashrate/watts) then an R9290
Optimizations leading to 15kH/s or 20KH/s per thread or more should mean the Cortex A9 is more power efficient than the AMD GPU.
These new Cortex-A17 procs (2014) seems considerably more powerrful than the A9