Husky CPU Cores
The computational x86 cores in the new Llano processors are codenamed Husky. However, there is not that much new about them, actually. They use the same K10 “Stars” microarchitecture, which is currently used in all Socket AM3 processors. And the promising Bulldozer microarchitecture should arrive into the hybrid AMD processors only next year. So, at this point we shouldn’t expect Llano to work any performance wonders, at least in traditional applications.
At the same time, AMD engineers tried to freshen up the old microarchitecture in some way and improve Husky cores performance at least a little bit over that of the cores inside Athlon II and Phenom II processors. We are going to see during our test session, how successful this attempt was, but the official data claim a 6% average boost.
It was very easy to achieve: by simply increasing the L2 cache memory. So, each Llano core has its own 1 MB L2 cache. However, the new processors have absolutely no shared L3 cache, so their total cache-memory size is not that big after all, according to today’s standards.
Besides increased cache, Husky cores have improved branch prediction unit and optimized primary buffers: instructions reorder buffer becomes 20% larger, and the load/store buffers have doubled in size. Also Husky has a separate hardware divider, which accelerates corresponding operations. As we see, there are not too many changes, and all of them are minor. The basis of K10 microarchitecture remained completely untouched that is why Husky can only process no more than three instructions per clock cycle, just like all preceding cores.
Obviously, the developers didn’t really focus on increasing the performance of the x86 cores in Llano processors. They had different priorities. First of all, they had to do their best to improve energy-efficiency of the new Husky, because CPUs on K10 microarchitecture can’t boast good power readings. Secondly, they had to seriously address the connection and communication between system memory, computational cores and the graphics core. This is where all the significant improvements and innovations actually took place.