Shining a Light on Intel’s Silvermont Mobile Processor Claims

by Matt Wuebbling

ARM hit back at Intel this week at Computex, asserting that its Cortex CPU cores that ship today both outperform and run at lower power than Intel’s future next-gen mobile processor, Silvermont.

Cores from the UK-based semiconductor IP group are known for their low-power capabilities and run a vast proportion of the world’s mobile devices. And they’re starting to get known for high performance, as well, such as with the quad Cortex-A15 CPUs built into Tegra 4, the world’s fastest mobile processor.

But Intel has recently been claiming that Silvermont is 1.6 times faster and 2.4 times more power efficient than Cortex.
ARM dismissed those charges at its event here in Taipei. It showed data with the accompanying chart that compares Cortex against Intel’s Silvermont claims.

Based on actual measurements of Intel Atom chips shipping today and Intel’s own claims of future performance, today’s current performance of Cortex-A15 processors are 30% more efficient than Intel’s future Silvermont chip.

ARM also noted that Intel’s x86 processors create compatibility issues on Android systems, which require them to “emulate” an ARM processor for apps to run properly. That’s no small issue, as fully 84% of the top games and 64% of top apps use native ARM code.

Emulation, unfortunately, has several side effects. For starters, it doesn’t always work. And, when it does work, it degrades performance and burns more energy. That’s because the x86 processor is “emulating” the intended processor’s instruction set, which requires a lot of heavy lifting. In any event, neither option is helpful for a mobile device.

There’s a rich tradition from the PC era of opposing architectures failing due to poor emulation results. SPARC, Transmeta and MIPS, among them.

The moral of the story is there’s really no need to rely on emulation when so many great ARM-based solutions are already available.