AMD Kaveri APU Architecture Detailed – Next Generation APU Featuring Steamroller and GCN Cores

AMD Kaveri APU Architecture Detailed – Next Generation APU Featuring Steamroller and GCN Cores

AMD’s next generation Kaveri APU architecture has been thoroughly detailed by PC.Watch which
shows how the fourth generation APU platform from AMD combines the
latest Steamroller and Radeon GCN cores, sharing the memory dynamically
through HUMA and HSA enhancements. AMD also demonstrated Kaveri APU at
their 2013 Computex seminar which can be seen here.

AMD Next Generation Kaveri APU Architecture Detailed

AMD launched their Richland “3rd Generation” APU platform last month which was an update to the already launched Trinity APU platform. Since the Richland APUs are a refresh of the Trinity platform,
the performance was not improved much but it did bring enhanced clock
speeds and much more power efficiency. AMD achieved this by tweaking
their Piledriver core which itself is a revision of the Bulldozer architecture. However, we knew that AMD’s Richland APU platform would be short lived since AMD had already planned to launch its fourth gen Kaveri APU sometime in Q4 2013.

Kaveri APU Equips 28nm Steamroller Core

The biggest architectural change Kaveri APU features is the use of the latest 28nm Steamroller architecture that is a true multi-threaded architecture focusing on enhancing the IPC (Instruction-Per-Cycle) by upto 25%. In each module, two separate threads are provided with their own parallel instruction decoder, due to enhancements, the steamroller die would be larger than Bulldozer and Piledriver with each module housing two steamroller cores with a shared L2 cache. You can see the block diagram for the differences between the Bulldozer and Steamroller architecture below:
AMD Steamroller vs Bulldozer
One thing to note is that the Kaveri APU architecture is not only built around the 28nm Steamroller architecture but also features the 28nm GCN graphics module. Llano APUs featured the VLIW5 architecture while Trinity and Richland used the updated VLIW4 architecture but still older compared to the discrete GPU offerings. Kaveri APU on the other hand makes use of the Radeon GCN (Graphics Core Next 2.0) architecture. The 2.0 represents an enhanced and efficient design that aims to improve graphical performance while keeping the power consumption under limits.
AMD Steamroller

AMD GCN Architecture Powers Kaveri Integrated GPU

On the GPU side, Kaveri APU would make use of upto 512 stream processors
or (MADs) which amount to 8 compute units. It is mentioned that the
number of stream processors would range from 384 SPs to 512 SPs though
it could feature even a higher number such as 768 SPs. The AMD Radeon HD
7750 features 512 SPs while the upcoming Radeon HD 7730 would feature
384 SPs so we are pretty much looking at performance levels of a
discrete entry level GPU here which would be fantastic for a integrated
graphics module. The total performance on the compute end would fall
above the 1 TFLOPs limit amounting the GPU and FPU performance for the
CPU core.
Though, we are skeptical if we will see a higher number of stream
processor count in AMD Kaveri APU architecture since the memory type is
still limited to DDR3 as seen through the FM2+ motherboard showcased at
Computex 2013. DDR3 memory bandwidth could become a slight bit of an
issue for an integrated graphics with higher stream processor count but
AMD might have an answer to solve this. HUMA and HSA enhancements would
allow the GPU and CPU to dynamically share the same virtual memory
address but we don’t know if that would help solve the bandwidth
issues.Nevertheless, the GCN part on the Kaveri APU sound great since it
would atleast allow budget gamers to play the latest titles without
spending much on a discrete GPU.
AMD Kaveri GPU
A major feature to be implemented in the Kaveri
APUs is the HUMA memory architecture which is part of HSA
(Heterogeneous System Architecture) which would allow PCs to make use of
a unified memory architecture which would allow cross sharing of system
ram between the GPU and CPU. This would enhance the way PCs access and
communicate with their memory.

AMD Kaveri APU – FM2+, A88X/A78X Chipset, Backwards Compatibility With Trinity/Richland

FM2 Socket
AMD Kaveri APU platform would launch with the AMD A88X “Bolton D4″ and A87X chipsets on the socket FM2+ motherboards. The socket FM2+ would be backwards compatible
with both Richland and Trinity APUs which is a plus point but Kaveri
won’t operate on the FM2 motherboards due to different pin layout.
Kaveri would launch in Dual and Quad core steamroller SKUs with GCN
enabled integrated graphics processors. Desktop models would range
between 100 and 65W TDPs while mobility models would have 35W TDP and
even lower for specific APUs, Kaveri would also arrive in the server
market as the Berlin platform. Expect more details in the upcoming months, launch takes place in Q4 2013. Do read the full article at PC.Watch for a detailed intro at Kaveri.
AMD Kaveri GPU Processors AMD Kaveri APU Die Size

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