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Feature Articles
AMD Trinity APU - A Notebook Platform Performance Review
By Vijay Anand, Leo Boon Yeow & James Lu - 15 May 2012,8:00pm

Trinity's New Graphics Engine, Power Optimization & Core Enhancements

The Graphics Quotient

An article on AMD”s Fusion APU processors is far from complete with if we omitted the advances made on its built-in graphics engine. After all, the integration of a powerful graphics core to complement mainstream class CPU cores is the main formula ever since Fusion processing platform began.

On the Trinity APU, the graphics core used is a Radeon HD 7600M class GPU, but unlike the naming suggestion, it’s not based on the newer Southern Islands architecture, but that of the Northern Islands series (Radeon HD 6000 series) - this was first mentioned here. To be specific, it sports the VLIW4 core design first used on the high-end Caymen GPUs (Radeon HD 6900 series) that is more performance optimized per die area and is easier to schedule/manage workloads. This also means that the number of stream processing units (or Radeon cores) would seem less than the previous generation IGPs, but you’ll have to understand that they are different in architecture and capabilities. The Triniy APU’s graphics core is supposed to deliver actual performance that is roughly in the range of Radeon HD 6600-class GPUs.

The Trinity APU’s graphics core block diagram – essentially a cut down variant of the Northern Islands architecture, more specifically Caymen’s (Radeon HD 6900 series).

Some people may have thoughts if the integrated graphics is really discrete class graphics and AMD assured us that the IGP core is equivalent to the identically named mobile discrete GPU. This means the Radeon HD 7660G on the A10-4600M APU performs similar to a mobile Radeon HD 7660M GPU module (if a direct equivalent exists). You’ll notice that the “G” suffix refers to the IGP edition, whereas “M” suffix refers to the mobile GPU variant. Later in our performance results, you’ll notice that this is somewhat true.

However there's more as these integrated GPUs also take some of the best features off the Southern Island GPUs like the AMD HD Media Accelerator (includes UVD 3.0 and Accelerated Video Converter), Video Compression Engine (VCE), DisplayPort 1.2 support and AMD Eyefinity technology for up to quad display capability. To be precise, the integrated graphics core has 3 independent display controllers, while the fourth display is driven by a software controller via DisplayPort 1.2 daisy-chain connectivity.

Overall, you could say that the Trinity integrated graphics core is quite an amalgamation of features across different GPU architectures. Not to forget, highlight features that were first introduced in the Llano’s graphics cores are also present in Trinity such as AMD SteadyVideo, CrossFireX support with an optimal similarly classed Radeon HD mobile GPU module, and Switchable graphics technology. They work pretty much the same as we last discussed in our mobile Llano platform article. For recommended compatible mobile graphics modules, AMD lists that their entire A10, A8 and A6 series of APUs can easily work with these following “Thames” GPU cores - Radeon HD 7670M, 7650M, 7550M, 7510M and 7450M (Seymour). Of course, this guidance is for the system integrators as consumers often have no say in the final product’s specification.


Power Optimization Features and Other Trinity Core Enhancements

As with any new processor (or APU), you can expect a slew of power optimizations that are important to their increased performance-per-watt proposition. We list some of the main optimizations here:-

  • New Core C6 (CC6) power state enables powering down individual compute modules. This was present in the desktop AMD FX, but is new to the Fusion processors.
  • Unified Northbridge for better APU power management (power gated when idle)
  • Dynamic DRAM speed changes via memory P-state support
  • Supports 1.25V DDR3 DIMMs
  • PCIe and Display PHY controller power gating
  • SVI-2 Voltage regulator interface for speedier voltage transitions and increase efficiency
  • Video Compression Engine (VCE) to help reduce data footprint and hence reduced workloads that translate to power savings

Further to power optimization matters, AMD also tightened up how the different units within the Trinity APU share data efficiently with a new set of interfaces like FCL, RMB and IOMMU v.2 (the latter of which is key to supporting the latest features offered on discrete GPUs when paired with the integrated graphics engine):-

The various interfaces and buses within the Trinity APU to help accelerate data flow; consequently it improves performance and the consumers overall usage experience. 

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