An Introduction to Carrizo - AMD 6th Gen APU - Article Page 1

Carrizo - The mobile architecture and products

AMD today launches their Carrizo based Mobile APUs, the new APU architecture makes use of Excavator CPU cores and up-to eight GCN 1.3 based graphics cores.  AMD APUs have a unique architecture: they have AMD CPU modules, cache, and a discrete-class graphics processor all on the same die, using the same bus. Albeit the new architecture resembled a lot like Kaveri, this latest iteration of their mobile APUs will be released in three models, all with updated CPU cores, better graphics performance and an updated video decoder engine that supports HEVC for Ultra HD video.
 

AMD APUs have a unique architecture: they have CPU modules, cache, and a discrete-class graphics processor all on the same die, using the same bus. Albeit the new architecture resemblesKaveri quiet a bit, it isn't. This latest iteration of their mobile APUs will be released in three models, all with updated CPU cores, better graphics performance and an updated video decoder engine that supports HEVC for Ultra HD video. As you can see, Carrizo is a 28nm process fabbed chip, compared to Intel who is full steam ahead with its 14nm FinFET designs. AMD thinks big and shoots high on the ability to squeeze as much performance per watt out of the larger gate size, before it will shrink processes to 14nm in a later stage.
 

Die shot of Carrizo

For the 6th generation of the A-series processor, AMD wanted something way more energy friendly. This means more battery life with the new APU. The excavator cores for example have been optimized for a 15W design point, that's next to a performance IPC increase of roughly 9 to 13% per core.   Carrizo has 3.1 billion transistors, 29 per cent more than the 28nm Kaveri yet has the same size die. The extra transistors are used for the graphics hardware, the integrated Southbridge (which controls the PC's peripherals), acceleration for 4K H.265/HEVC video playback and things like HSA.

Processor wise these APUs will come with Excavator CPU cores, Excavator is a micro-architecture under development by AMD to succeed Steamroller. The Carrizo APU is designed to be HSA compliant. The excavator cores will have support instructions sets such as AVX2, BMI2 and RdRand. For the Excavator series AMD was able to reduce application core by a good 23 per cent, allowing Excavators to run at a higher clock frequency than Steamrollers, yet it will consume roughly the same amount of power. The L2 cache for the cores has been halved to 1MB (compared to kaveri), this creates more die area space for other things. The per-core L1 cache has been doubled to 32KB.

Where does this all lead to ? Well, AMD’s CEO Lisa Su already noted that Carrizo will deliver the largest ever generational leap in performance-per-watt for mainstream APUs. 
 

Carrizo should offer many efficiency improvements on evolutionary CPU and GPU architectures. AMD is making bold comparisons, but overall power consumption should be halved compared to last generation products with a perf per watt increase to 2.4x. We'll continue on the next page.