The Coming War: ARM versus x86

JavaScript performance
JavaScript performance has become very important as cloud-based computing has finally begun to take hold with the appearance of solutions like Google Apps, Zoho Office, Adobe’s Acrobat.com, Aviary and many more applications. Google Android operating system largely foregoes native applications and leverages Web-based JavaScript programs. Jolicloud Linux takes a similar but less aggressive tack allowing native and cloud-based applications to seamlessly co-exist.

There are several widely used JavaScript tests that run across all of the CPUs examined in this report. However, it is very important to run these tests on the same browser across all platforms.  Even specific browser version is also very important because JavaScript performance varies wildly from browser to browser and version to version as web browser developers push each other in a mad race to provide the fastest JavaScript engines.

Thankfully, Firefox 3.5.x is available for each system included in this report and we used it for these tests.

FutureMark Peacekeeper Benchmark


FutureMark Corporation, the maker of PCMark and 3DMark, has introduced its own JavaScript benchmark called Peacekeeper. FutureMark Peacekeeper is hands down the most elaborate JavaScript benchmark currently available, although it is difficult to assess its validity. PeaceKeeper is the only JavaScript test in our roundup that had complex graphical components.

The Freescale i.MX515 ARM system fared poorly against its x86 rivals across all Peacekeeper tests. This might be partially accountable to the slow main memory subsystem which saddled Cortex-A8. The i.MX515 Cortex-A8 only has 256kB of L2 cache compared to 512kB for the Athlon and the Atom and 1,024kB for the Nano, so it is much easier for a benchmark to spill out of the Cortex-A8’s L2 cache and into its extremely slow main memory.

ARM representatives agreed that the Cortex-A8’s poor showing on FutureMark Peacekeeper is most likely due its L2 handicap, perhaps making Peacekeeper, in the context of this report, more of a comparison of memory subsystems, not processors.

Note also that the ARM system failed to complete the Peacekeeper complex graphics test.

The VIA Nano L3050 was the clear winner of FutureMark’s PeaceKeeper, besting all of its rivals on every test. Even though the Intel Atom N450 was far behind the two other x86 chips, its overall score was nearly twice that of the ARM system. Again, keep in mind that the Atom also ran with a 25 percent clock speed advantage over the other chips in this comparison. Also be aware that JavaScript is not threaded, so the Atom’s Hyper-Threading engine won’t help it much on JavaScript tests.

Google V8 Benchmark: Flawed but popular
With Google in the lead of cloud-based computing efforts, it should not be surprising that the search engine giant also provides its own JavaScript benchmark. Unfortunately, the Google V8 benchmark does not behave like a very good benchmark at this point, demonstrating large run-to-run variation and superlinear scaling. Nevertheless, Google V8 is a popular JavaScript benchmark, so we included it here.



The Google V8 benchmark closely reproduced FutureMark Peacekeeper’s results. VIA’s Nano L3050 won every test by significant margins again. The Atom trailed the other x86 processors badly, but still nearly doubled the ARM Cortex-A8’s showing.

SunSpider JavaScript Test
Our final JavaScript benchmark is SunSpider, perhaps the most popular JavaScript test in use today.



Again, the ARM Cortex-A8 does not look good, faring only slightly better than on the other two JavaScript benchmarks.

The VIA Nano L3050 barely pulls out an overall win, its score hurt by very poor performance on bit level operations. The ARM Cortex-A8 beats the Nano on two of these tests. Despite its age, the AMD Mobile Athlon based on the Barton core has delivered competitive performance across nearly all tests.

I must state at this point that the JavaScript results do seem to reflect the relative, subjective, overall feel of the four systems. Despite its strong showing on many integer tests, the Freescale i.MX515-based Pegatron system feels much more sluggish than all three of the x86 systems; the Pegatron’s extremely slow memory subsystem doubtlessly contributes to this issue. The Atom N450 is also clearly more lethargic than either the AMD Mobile Athlon or the VIA Nano L3050 systems. The AMD and VIA systems are essentially indistinguishable during normal usage.


2D Graphics Performance
Take the following chart with a grain of salt because the video subsystems across the three systems are very dissimilar. The VIA, Intel and Freescale systems all used integrated graphics while the AMD system was equipped with a discrete NVIDIA NX6200 AGP card.



Even though the three x86 systems ran at 24-bit color depth, they were all two to three times faster than the ARM system that ran at only 16-bit color depth. We tested all systems at 1024x768 [XGA] resolution except the Atom, which we tested at the native panel resolution of 1024x600.