First Look: Llano vs. Propus
Before we get to “serious” testing, let’s take a quick look at Llano and Athlon II X4 processors working at the same clock frequencies. This will show us how efficient the improvements in the new Husky core actually are. AMD claims there is a 6% performance boost, however, they also take into account larger L2 cache. We decided to focus exclusively on the microarchitectural improvements, which could be tested using short synthetic benchmarks that do not overload the L2 cache memory. SiSoftware Sandra suite offers s decent set of tests for that.
To ensure a fair comparison we locked the clock frequency of Llano as well as Athlon II X4 processor at 2.4 GHz and disabled Turbo Core technology.
Microarchitectural improvements in Husky processors have very little practical value. However, the biggest gain occurs when the processor works with integer data. So, in most cases when Llano working at the same clock frequency outperforms the previous-generation processors, it will be either due to larger L2 cache memory or to stream processors of the advanced graphics core.
However, there is one more thing. AMD changed the memory controller in their Llano processors. Now it supports faster DDR3 memory and works with three independent memory access paths with different priority levels. We used Cachemem test from Aida64 suite to test its performance. In all tests our DDR3-1600 memory worked with 9-9-9-27-1T timings.
No improvement whatsoever. The memory controller needed additional arbitrage to ensure that not only processor cores but also the graphics core could properly work with the memory sub-system. As a result, the practical bandwidth of the bus between the processor cores and memory has dropped, because x86 cores do not have the highest priority level. L2 cache also slows down because of its increased size, which at the same time compensates the loss in speed.