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Moorestown And Turbo Boost

Intel Developer Forum, Day Two: 6 Gb/s, USB 3.0, And Lucid
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The deep dive session on Moorestown, Intel’s update to the wildly successful Atom processor, was heavily attended. Perhaps the most interesting aspect of Moorestown is how far it will distance itself from the PC.

Moorestown's power consumption at standby will be reduced by up to 50x. Moorestown will be the core of a new line of SoCs (systems-on-chip) from Intel. So, unlike the current Atom, we may see many different instantiations of Moorestown products, aimed at highly segmented markets.

The Moorestown platform will mainly consist of two parts: Lincroft (the SoC) at 45nm and Briertown. Lincroft will have the CPU, MIPI display interface, LP (low power) DDR memory controller, plus 2D/3D graphics and memory controller. Briertown is the second chip which has SDIO, audio engine, modem for 3G, and so on.

Lincroft brings in the display and memory controller into the CPU die, plus graphics and video decode capabilities. The new CPU will have Hyper-Threading and “burst mode,” similar to Turbo Boost on Intel’s desktop and laptop CPUs.

Power reduction is partly enabled by moving to the type of I/O infrastructure used in handheld and mobile devices, including SDIO, MIPI (for displays), and low power DDR memory. Also, the graphics and video decoders can run independently of the CPU at lower power. So graphics, video decode, and audio are fixed-function coprocessors.

What’s being left out of Moorestown are PC interfaces. For example, MIPI is replacing LVDS as the display interface. PCI Express is out entirely. USB will be present, but not SATA I/O. If Intel’s goal is to segment Atom based netbooks so that they’re more limited than PCs, then Moorestown will accomplish this. On the other hand, it will be much more power efficient than a PC-like device, while maintaining Atom-like levels of performance.

Turbo Boost

We’ve talked about Turbo Boost in the past. Turbo Boost is a feature of Intel’s Nehalem CPU that allows the frequency of utilized cores to ramp up to higher clock speeds in order to bolster the performance of a lightly-threaded app. The limiting factor is TDP--thermal design power. As long as the overall CPU remains within the thermal budget, the core (or cores) can be pushed harder than the default frequency to get a bit more performance.

With Intel’s upcoming Arrandale and Clarkdale 32nm dual-core CPUs (which support four threads via Hyper-Threading), Turbo Boost also affects the on-die integrated graphics core. Graphics Turbo will be introduced with Intel’s Arrandale 32nm mobile CPU. Intel is building in a “graphics turbo manager” that manages the power budget for the integrated graphics core. There will be a Turbo Boost driver that handles Turbo Boost across the two CPU cores and the graphics core.

In the case of running a graphics-intensive application that’s not hitting the CPU very hard, then the GPU clock frequency scales up, just as it would on a CPU core affected by Turbo Boost. Currently, the Arrandale Turbo Boost driver will be a Windows 7 component, and only support the integrated graphics core.

Should the laptop instead include a discrete graphics chip, graphics turbo doesn’t affect its performance. However, Turbo Boost still has some impact on the graphics chip, since the processor has PCI Express and memory controllers on board.

The upshot of all this, from the point of view of companies building laptops, is that the design of the thermal solutions to keep notebooks cool are more critical than ever. Turbo Boost will keep the system running closer to the maximum thermal envelope. So, it’s important that Arrandale laptops have proper cooling solutions. Intel has data that shows the skin of the laptop (palm rests, the underside of the case) often become hotter than the actual CPU, which affects its overall performance envelope. A poorly designed cooling solution will mean the system won’t run at its maximum possible performance under Turbo Boost.

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