The ARM vs x86 Wars Have Begun: In-Depth Power Analysis of Atom, Krait & Cortex A15
by Anand Lal Shimpi on January 4, 2013 7:32 AM EST- Posted in
- Tablets
- Intel
- Samsung
- Arm
- Cortex A15
- Smartphones
- Mobile
- SoCs
Final Words
Whereas I didn't really have anything new to conclude in the original article (Atom Z2760 is faster and more power efficient than Tegra 3), there's a lot to talk about here. We already know that Atom is faster than Krait, but from a power standpoint the two SoCs are extremely competitive. At the platform level Intel (at least in the Acer W510) generally leads in power efficiency. Note that this advantage could just as easily be due to display and other power advantages in the W510 itself and not necessarily indicative of an SoC advantage.
Looking at the CPU cores themselves, Qualcomm takes the lead. It's unclear how things would change if we could include L2 cache power consumption for Qualcomm as we do for Intel (see page 2 for an explanation). I suspect that Qualcomm does maintain the power advantage here though, even with the L2 cache included.
On the GPU side, Intel/Imagination win there although the roles reverse as Adreno 225 holds a performance advantage. For modern UI performance, the PowerVR SGX 545 is good enough but Adreno 225 is clearly the faster 3D GPU. Intel has underspecced its ultra mobile GPUs for a while, so a lot of the power advantage is due to the lower performing GPU. In 2D/modern UI tests however, the performance advantage isn't realized and thus the power advantage is still valid.
Qualcomm is able to generally push to lower idle power levels, indicating that even Intel's 32nm SoC process is getting a little long in the tooth. TSMC's 28nm LP and Samsung's 32nm LP processes both help silicon built in those fabs drive down to insanely low idle power levels. That being said, it is still surprising to me that a 5-year-old Atom architecture paired with a low power version of a 3-year-old process technology can be this competitive. In the next 9 - 12 months we'll finally get an updated, out-of-order Atom core built on a brand new 22nm low power/SoC process from Intel. This is one area where we should see real improvement. Intel's chances to do well in this space are good if it can manage to execute well and get its parts into designs people care about.
Device level power consumption, from our iPhone 5 review, look familiar?
If the previous article was about busting the x86 power myth, one key takeaway here is that Intel's low power SoC designs are headed in the right direction. Atom's power curve looks a lot like Qualcomm's, and I suspect a lot like Apple's. There are performance/power tradeoffs that all three make, but they're all being designed the way they should.
The Cortex A15 data is honestly the most intriguing. I'm not sure how the first A15 based smartphone SoCs will compare to Exynos 5 Dual in terms of power consumption, but at least based on the data here it looks like Cortex A15 is really in a league of its own when it comes to power consumption. Depending on the task that may not be an issue, but you still need a chassis that's capable of dissipating 1 - 4x the power of a present day smartphone SoC made by Qualcomm or Intel. Obviously for tablets the Cortex A15 can work just fine, but I am curious to see what will happen in a smartphone form factor. With lower voltage/clocks and a well architected turbo mode it may be possible to deliver reasonable battery life, but simply tossing the Exynos 5 Dual from the Nexus 10 into a smartphone isn't going to work well. It's very obvious to me why ARM proposed big.LITTLE with Cortex A15 and why Apple designed Swift.
I'd always heard about Haswell as the solution to the ARM problem, particularly in reference to the Cortex A15. The data here, particularly on the previous page, helped me understand exactly what that meant. Under a CPU or GPU heavy workload, the Exynos 5 Dual will draw around 4W. Peak TDP however is closer to 8W. If you remember back to IDF, Intel specifically called out 8W as a potential design target for Haswell. In reality, I expect that we'll see Haswell parts even lower power than that. While it may still be a stretch to bring Haswell down to 4W, it's very clear to me that Intel sees this as a possiblity in the near term. Perhaps not at 22nm, but definitely at 14nm. We already know Core can hit below 8W at 22nm, if it can get down to around 4W then that opens up a whole new class of form factors to a traditionally high-end architecture.
Ultimately I feel like that's how all of this is going to play out. Intel's Core architectures will likely service the 4W and above space, while Atom will take care of everything else below it. The really crazy part is that it's not too absurd to think about being able to get a Core based SoC into a large smartphone as early as 14nm, and definitely by 10nm (~2017) should the need arise. We've often talked about smartphones being used as mainstream computing devices in the future, but this is how we're going to get there. By the time Intel moves to 10nm ultramobile SoCs, you'll be able to get somewhere around Sandy/Ivy Bridge class performance in a phone.
At the end of the day, I'd say that Intel's chances for long term success in the tablet space are pretty good - at least architecturally. Intel still needs a Nexus, iPad or other similarly important design win, but it should have the right technology to get there by 2014. It's up to Paul or his replacement to ensure that everything works on the business side.
As far as smartphones go, the problem is a lot more complicated. Intel needs a good high-end baseband strategy which, as of late, the Infineon acquisition hasn't been able to produce. I've heard promising things in this regard but the baseband side of Intel remains embarassingly quiet. This is an area where Qualcomm is really the undisputed leader, Intel has a lot of work ahead of it here. As for the rest of the smartphone SoC, Intel is on the right track. Its existing architecture remains performance and power competitive with the best Qualcomm has to offer today. Both Intel and Qualcomm have architecture updates planned in the not too distant future (with Qualcomm out of the gate first), so this will be one interesting battle to watch. If ARM is the new AMD, then Krait is the new Athlon 64. The difference is, this time, Intel isn't shipping a Pentium 4.
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powerarmour - Friday, January 4, 2013 - link
"Intel doesn't want to create a chip that cuts into it's very profitable mainstream CPU market."Indeed, they've left Cedar Trail to fester and die by totally withdrawing driver support :-
http://communities.intel.com/message/175069#175069
Quite a lot of desktop Atom hardware is still on the market, and they are trying their best to kill it off.
djgandy - Friday, January 4, 2013 - link
All that says to me is that they don't care about Win7 i.e. non tablets.Krysto - Friday, January 4, 2013 - link
Cortex A15 coupled with Cortex A7 will use half the power on average. Also, I told you before that Mali T604 is more efficient than PowerVR in the latest iPads, and that's why Apple managed to use a more powerful GPU - because it's more inefficient. They sacrificed energy efficiency for performance, because they can use a very large battery in the iPad.I saw you're trying hard to "prove something" about Intel lately, and I'm not sure why. Is Intel is biggest "client" when they pay you for reviews here? Is that why you're trying so hard to make them look good?
You're also always making unebelivable claims about what Intel chips will do in the future. Even if they get Haswell to 8W (is that for CPU only? The whole SoC? Is it peak TDP? Will it still need fans?), you do realize a Haswell chip costs as much as the whole BOM of an iPhone 5 right? Haswell chips will never arrive in smartphones, or in tablets that are competitive on price.
Tetracycloide - Friday, January 4, 2013 - link
You're always making "unebelivable" claims about what corruption does here. Do you have anything to back up your allegations to a normal person who would view any excitement about future possibilities as some kind of damning evidence that the writer must be on the take? It's like you think everyone that doesn't share your opinion of Intel is paid to have that opinion or something.trivik12 - Friday, January 4, 2013 - link
Haswell ULV is a SOC. So the platform TDP was < 8W. You like it or lot intel has the best process technology and ultimately they will produce a platform which is faster and lower TDP.That being said ARM will dominate the smartphone market and even majority of low end laptops. I see intel existing only in mid to higher end smartphone plus tablets > $500.
I am personally waiting for broadwell based tablet which should hopefully cut power even more in 14nm process.
djgandy - Friday, January 4, 2013 - link
You'd hope two brand new technologies would be better than two 3/4 year old ones wouldn't you. Clearly you are blinded by your love for ARM in the same way many here are blinded by love for Nvidia and actually consider Tegra 3 a competitive SOC.I don't think many people would be astonished to find that the T604, an architecture only released a few months back, is more efficient than PowerVR Series 5, dating back to 2008.
Why are people so shocked to find that Intel can make a low power chip? It's not some kind of magic, it is a business goal. Power is a trade off just like performance. When you have desktop systems the trade off for using more power is seen as a pro for a 40-50% performance gain.
mrdude - Friday, January 4, 2013 - link
He's spot on about the pricing issue, though. Intel isn't going to start selling Haswell SoCs for $30, and if they do then they'll quickly go out of business. It's a completely different business model that they're trying to compete with. The Tegra 3 costs $15-$25 (and way closer to that $15 to date) while Intel charges $70+ for their CPU+GPU, and that's before you get to the chipset, WiFi and the rest. A low-TDP Haswell chip might offer great performance and fit in the same form factor (tablets), but if the tablet ends up costing $800+ and isn't Apple, well... nobody cares.It's not just a matter of performance but performance-per-dollar and design wins. Intel can't afford to drop prices to competitive levels on their Core products unless they can supplement it with very high volume. For very high volume you need to sell a lot of competitive SoCs that can do it all at a very reasonable price. The Tegra 3 was a big success not because it was an amazing performer, but because it offered decent performance for a very low price tag. Can Intel afford to do that with their cash cow business slipping? Remember that x86 seeing drops in sales and PCs aren't exactly doing very well right now. Intel already had to drop their margins and they've let fabs run idle and sent home engineers at their 14nm fab in Ireland all the while processor prices haven't decreased even a tiny bit. Those aren't signs of a company that's willing to compete on price
Homeles - Friday, January 4, 2013 - link
I'm more than willing to pay for the performance premium.mrdude - Friday, January 4, 2013 - link
While you may be willing to fork over that much cash, most people won't. If you don't believe me, check out the recent sales figures of Win8 devices. The Win8 tablets (excluding Surface RT) don't even make up 1% of all Win8 products sold. That's not poor, that's absolutely horrible. On the other side the cheap Android tablets and smartphones have been gaining significant market share and outselling even the iPhone and iPads. Price matters. A lot. Furthermore, device makers/OEMs are more likely to go with the cheaper SoC if the experience is roughly equal. Remember that a majority of tablet and smartphone buyers don't browse Anandtech for benchmarks but buy based on things like display quality or whether it's got a nice look (or brand name, in the case of Apple). If an OEM can take that $60 saved and put it towards a better display, a larger battery or more NAND then that means a lot more in differentiating yourself from the competition than being 10-15% faster in X benchmark.People forget that these are SoCs and not CPUs. They also forget that these aren't DIY computers but tablets. Think about how much people complain when they see a $900 Ultrabook with a crappy 1366x768 TN display but those same people don't utter a word about how Intel's ULVs cost the same as their 35W parts. If the Intel chip was cheaper you'd probably have a better display or a cheaper price tag. This same notion extends to tablets and smartphones.
Qualcomm is in a place where they can offer something everybody wants; their LTE is second to none. What does Intel have to offer to warrant Intel prices? Currently Intel's chipsets cost as much as an entire Tegra 3 SoC. x86 PC/server and ARM SoCs are in a completely different universe when it comes to pricing, and unless you've got something special (see Qualcomm or Apple) or you're making and selling the device (Samsung), then you're going to have a very rough time of it.
jeffkro - Saturday, January 5, 2013 - link
I paid $15 to "upgrade" my laptop and have since gone back to win 7. A lot of people simply don't want win 8 at any cost.