For the past eighteen months, Intel has paraded its new ‘Lakefield’ processor design around the press and the public as a paragon of new processor innovation. Inside, Intel pairs one of its fast peak performance cores with four of its lower power efficient cores, and uses novel technology in order to build the processor in the smallest footprint it can. The new Lakefield design is a sign that Intel is looking into new processor paradigms, such as hybrid processors with different types of cores, but also different stacking and packaging technologies to help drive the next wave of computing. With this article, we will tell you all you need to know about Lakefield.

Part Smartphone, Part PC

When designing a processor, there are over a thousand design choices to be made. The processor can be built to tackle everything, or it can be aimed at a niche. For high performance computing, there might be a need for a high power, high performance design where cooling is of no consideration – compare that to a processor aimed at a portable device, and it needs to be energy efficient and offer considerable battery life for a fixed battery size. There is also the cost of designing the product, how much to invest into research and development, how many units are expected to sell, and thus how many should be produced and what size the product should be. What the price range of the target market is can be a huge factor, even before putting pen to paper.

The New Samsung Galaxy Book S

This is all why we have big multi-core processors with lots of compute acceleration in servers, more moderate power and core counts in home machines that focus on single core performance and user experience, and why smartphone processors have to physically fit into a small design and offer exceptional battery life.

Laptop processors have always sort of fit into the middle of the PC and smartphone markets. Laptop users, especially professionals and gamers, need the high performance that a desktop platform can provide, but road warriors need something that is superbly efficient in power consumption, especially at idle, to provide all-day battery life as if they were on a good smartphone. Not only this, but the more energy efficient and the smaller the footprint of the processor and its features, the thinner and lighter the laptop can be, offering a premium design experience.

As a result, we have seen the ultra-premium notebook market converge from two directions.

From the top, we have AMD and Intel, using their laptop processor designs in smaller and smaller power envelopes to offer thin and light devices with exceptional performance and yet retain the energy efficiency required for battery life. For the most premium designs, we see 12-15+ hours of laptop battery life, as well as very capable gaming.

From the bottom, we have Qualcomm, building out its high-performance smartphone processor line into larger power envelopes, in order to offer desktop-class performance with smartphone-class connectivity and battery life. With the designs using Qualcomm’s processors, a user can very easily expect 24+ hours of battery life, and with regular office use, only charge the system once every couple of days. Qualcomm still has an additional barrier in software, which it is working towards.

Both of these directions converge on something in the middle – something that can offer desktop-class performance, 24hr+ battery life, capable gaming, but also has a full range of software support. Rather continue with trying to bring its processors down to the level it requires, Intel has decided to flip its traditional processor paradigm upside down, and build a smartphone-class processor for this market, matching Qualcomm in its bottom up approach while also looking into novel manufacturing techniques in order to do so.

This processor design is called ‘Lakefield’.

Lakefield at the Core, and the Atom

For the past two decades, Intel has had two different types of x86 CPU design.

The Big ‘Core’ CPU

Intel calls its high power/high performance x86 design the ‘Core’ family. This can make it very confusing, to differentiate between the general concept of a processor core and a ‘Core’-based processor core.

Over the years, Core-based processor cores have been designed for power envelopes from low-power laptops all the way up to the beefiest of servers. The Core line of processor cores implement more complex logic in order to provide additional acceleration, at the expense of physical size and power.

The Small ‘Atom’ CPU

The second type of x86 design from Intel is its more energy efficient implementation, called ‘Atom’. With the Atom cores, Intel simplifies the design in order to maximise efficiency for a given power or a given performance. This makes the design smaller, cheaper to manufacturer, but has a lower peak performance than the Core design. We typically see Atom designs in power restricted scenarios where performance is not critical, such as IoT, or low cost laptop designs.

Where Core Meets Atom

Normally we characterise a processor core design in terms of this power and performance. Due to the variation in the design, we see where some designs work best, at various points for a given power or for a given performance. In the case of Intel’s latest generation of Core and Atom hardware, it looks something like this, if we compare one thread against one thread:

Modified from Intel’s Slides

From this graph, which measures Performance on the bottom axis and power on the side axis, there is a crossover point where each design makes the best sense. When the demand for performance is below 58%, the Atom design is the most power efficient, but above 58% then a Core design is preferred.

Homogenous CPUs (all the same) vs
Heterogeneous CPUs (mix of different)

Now in modern processors, especially in laptops, desktops, and servers, we only experience one type of core design. We either have all Core or all Atom, and the performance is designed to scale within those homogeneous designs. It becomes a simple curve to navigate, and when more parallel performance is required, more of those types of cores are fired up to serve the needs of the end user. This has been the case for these markets for the last 30-50 years.

The smartphone space, for the last decade, has been taking a different approach. Within the smartphone world, there are core designs listed as ‘big’ and core designs listed as ‘little’, in the same way that Intel has Core and Atom designs.

These smartphone processors combine numbers of big cores with numbers of small cores, such that there is an intrinsic benefit to running background tasks on the little cores, where efficiency is important, and user experience related elements on the big cores, where latency and performance is important.

The complexity of such a heterogeneous smartphone-like design has many layers. By default most items will start on the little cores, and it is up to either the processor or the operating system to identify when the higher performance mode during a user experience moment is needed. This can be tricky to identify.

Then also comes the matter when a workload has to actually move from one type of core to the other, typically in response to a request for a specific level of performance – if the cores are designed significantly different, then the demands on the memory can likely increase and it is up to the operating system to ensure everything works as it should. There is also an additional element of security, which is a larger topic outside of the scope of this article.

Ultimately building a design with both big cores and little cores comes down a lot to what we call the scheduler. This is a program inside the operating system that manages where different background processes, user experience events, or things like video editing and games, get arranged. The smartphone market has been working on different types of schedulers, and optimizing the designs, for over a decade as mentioned. For the land of Intel and AMD, the push for heterogeneous schedulers has been a slow process by comparison, and it becomes very much a chicken and egg problem – there is no need for an optimized heterogeneous scheduler if there is never a heterogeneous processor in the market.

So why bring all this up?

Lakefield is the first x86 heterogeneous processor.

In its marketing, Intel calls this a ‘hybrid’ CPU, and we will start to see logos identifying this as such. At the heart of its design, Lakefield combines one of the big Core designs with a cluster of four smaller Atom designs, all into one single piece of silicon. In normal x86 processor talk, this is essentially a ‘penta-core’ design, which will commonly be referred to as a 1+4 implementation (for one big core and four small cores).

Intel’s goal with Lakefield is to combine the benefits of the power efficient Atom core with the better user-experience elements provided by the more power hungry but better peak performing big Core. As a result, it sits in the middle of Intel’s traditional homogeneous designs which only contain one type of x86 design – somewhere above the ‘all Atom’ 0+4 design and somewhere below the ‘all Core’ 4+0 design (in actual fact, it’s closer to 0+4).

Based on our conversations with Intel, and the small demonstrations we have seen so far, the best way to consider the new Lakefield processor is to consider it similar to one of the older quad-core Atom processors, with the benefits of the single core performance of a big Core. The cluster of four smaller Atom CPUs will take care of the heavy lifting and parallel performance requests, because there are four of them, while the big Core will respond when the user loads an application, or touches the screen, or scrolls a web browser.

Being a new form of x86 hybrid CPU is not the only thing that Lakefield brings to the table.

Now, just for some form of clarification, we have already had some experience with these sorts of hybrid CPU designs on operating systems like Windows. Qualcomm’s Windows on Snapdragon laptops, like the Lenovo Yoga, use a 4+4 design with the Snapdragon smartphone chips, and Qualcomm has had to work extensively with Microsoft to develop an appropriate scheduler that can manage workloads between the different CPU designs.

The main difference to what Qualcomm has done and what Intel is doing with Lakefield is in software support – Qualcomm processors run ‘Arm’ instructions, while Intel processors run ‘x86’ instructions. Most Windows software is built for x86 instructions, which has limited Qualcomm’s effectiveness in penetrating the traditional laptop market. Qualcomm's design actually allows for ‘x86 translation’, however its scope is limited and there is a performance penalty, but is a work in progress. The point being is that while we have not had a hybrid CPU scheduler for Windows on an x86 system previously, there has been a lot of work put in by Microsoft to date while working with Qualcomm.

Visualising Heterogeneous CPU Designs

Not to any sort of scale

Here are some examples of mobile processors, from Intel and Qualcomm, with the cores in green. On the left is Intel's own Ice Lake processor, with four big cores. In the middle is Intel's Lakefield, which has two stacked silicon dies, but it's the top one that has one big core and four small ones. On the right is Qualcomm's Snapdragon 8cx, currently used in Windows on Snapdragon devices, which uses four performance cores and four efficiency cores, but also integrates a smartphone modem onboard.

In this article, over the following pages, we'll be looking at Intel's new Lakefield processor in detail, covering the new multi-core design, discussing chiplets and Intel's new die-to-die bonding technology called Foveros, the implications of such a design on laptop size (as well as looking at the publicly disclosed Lakefield laptops coming to market), die shots, supposed performance numbers, thermal innovations, and the future for Lakefield. Data for this article has come from our research as well as interviews with Intel's technical personnel and Intel's own presentations on Lakefield at events such as HotChips, Architecture Day, CESIEDM, and ISSCC. Some information is dissected with helpful input from David Schor of Wikichip. We also cover some of Intel’s innovations with the scope of other semiconductor companies, some of which may be competitors.

A Stacked CPU: Intel’s Foveros
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  • ichaya - Sunday, July 19, 2020 - link

    SPEC is useful for some IPC comparisons, but it's questionable to use it for much else. PG bench in the phoronix link has a 50%+ speedup with SMT which is basically inline for perf/W/$ with Graviton 2 instance. The worst case is Casandra, but everything else is within ~5% for similar perf/$ if not comparable perf/W too since comparing TDP is workload dependent as well and not measured by most tests.

    XZ and Blender are ~45% faster with SMT in your openbenchmark link, but that's a 3900X (12-core/24-thread), so any comparisons to server chips (64-core Graviton 2) are unfair given power consumption and core differences. 4 times the L3 is also wrong, it's 50% more L2+L3 with half the cores and SMT if you're being fair between m6g.16xlarge or c6g.16xlarge and c5a.16xlarge.
  • Quantumz0d - Friday, July 3, 2020 - link

    Intel has lost it's edge. And this whole portable nonsense is reaching peaks of stupidity. Those Lakefield processor equipped machines will be close to $1000 for their thin and ultra light 1 USB C / 1 3.5mm audio jack, what a fucking disaster.

    I had owned one ultrabook which is Acer Aspire S3 and I used to even play DotA2 on that, and after 1-2 years the whole machine heated like crazy, I repasted, no dice, cleaned fans, nothing. And then battery also stopped holding a charge. Now what ? That stupid POS is dead, not even worth, meanwhile a Haswell machine with rPGA socket, and an MXM slot from 2013 and guess what ? the GPU got an upgrade to Pascal 1070 MXM from Kepler 860M.

    All these BGA trash machines will no longer hold charge nor have their serviceability, older ultrabooks atleast had a 2.5" drive, newer ones have NVMe SSDs, these 2 in 1 trash like most of the Surface lineup is almost impossible to even repair or service. And because of this thin and light market Windows 10 has been ruined as well to cater to this bs phenomenon and desktop class OS is hit with that ugly Mobile UX which lacks powerful software options, navigation and all. Plus you don't even get to repair it yourself due to non available servicing parts.

    With Apple HW same thing, full BGA not even NVMe SSDs, and now they also started to make their Mac OS look and feel like iOS trash. This whole mobile and ultra portable garbage is ruining everything, from gaming to the HW.
  • PandaBear - Monday, July 6, 2020 - link

    They don't want to cannibalize their highly profitable x86 business, so they have to give you crap for what you want if you want to pay less. The problem right now is other companies don't have to deal with this political monopoly BS and they are eating Intel for lunch.

    Most monopolies die this way: when their monopoly business is obsoleted and they hang on to it to milk the cow till it dies.
  • yeeeeman - Friday, July 3, 2020 - link

    Tigerlake should also be in the pipeline soon, right?
  • Deicidium369 - Saturday, July 4, 2020 - link

    Benchmarks showing it destroying AMD Renoir at single core, and within 17% on MT - despite half the cores...
  • watzupken - Sunday, July 5, 2020 - link

    "Benchmarks showing it destroying AMD Renoir at single core, and within 17% on MT - despite half the cores...

    Till we see the actual performance, you need to take these leaks with a lot of salt. The test bed are not revealed in leaks and it is not possible to ascertain if it is a realistic number. This we don't have to speculate for long since it should be out pretty soon.
  • pugster - Friday, July 3, 2020 - link

    Lakefield's 2.5w standby sounds kind of high. ARM cpu is probably much lower than that.
  • Ian Cutress - Monday, July 20, 2020 - link

    2.5 mW
  • ProDigit - Friday, July 3, 2020 - link

    Qualcomm has proven that a single fast core isn't enough. Intel needs to at least do 2 fast cores. Then add at least 6 atom cores.
    But if Intel wants to compete with AMD, it'll need to create a quad core big setup, with at least 10 to 12 atom cores.
    Any less will be too little. These are too little as is, competing against the 3000 series of AMD.

    It would be awesome, if Intel could make a 25W quad core cpu, paired with an additional 40 watts on atom cores. That's about 20 additional cores, or a 24 core cpu.
  • abufrejoval - Friday, July 3, 2020 - link

    A great article overall, very informative, deeply technical while still readable to a layman, very little judgement or marketing, allowing readers to form their own opinion: Anandtech at its very best!

    Not mentioned in the article and not covered by the comments so far is that the main driver behind Intel’s low power SoCs has been Apple: This is what Intel thought Apple would want and be happy with!

    And if you contrast it to what Apple will now do on their own, that makes me want to sell all my Intel shares: Good thing I never had any.

    This is another Intel 80432 or i860, tons of great ideas engineered into parts, but great parts don’t automatically make a convincing whole.

    And I simply don’t see them iterate that into many more designs over the next years at competitive prices: With that hot-spot governed layout between the two all the flexibility and cost savings a chiplet design is supposed to deliver goes away and you now have two chips in a very tight symbiosis with no scale-up design benefits.

    It’s a Foveros tech demo, but a super expensive one with very little chance of currying favors even at ‘negative revenues’ in the current market.

    X86 is not competitive in terms of Watts or transistors required for a given amount of compute. It didn’t matter that much in PCs, the competing servers were much worse for a long time, but in the mobile space, phones to ultrabooks, it seems impossible to match ARM, even if you could rewind the clock by ten years and started to take BIG-little seriously. Lakefield is essentially a case study for Core being too big and thus power hungry and Atom failing on performance.

    ISA legacy is still holding x86 from dying completely, but that matters less and less at both the top of the performance range with servers and at the bottom in mobile, where the Linux kernel rules supreme and many userlands and ISAs compile just fine.

    Gaming is a hold-out, but perhaps the last generation consoles on x86, gamer PCs alone too much of a niche to determine the future.

    The desktop will switch to who offers the bigger, longer lasting bang for the buck and there is a very good chance that will be ARM next.

    Microsoft may be allowed to blunder along with lackluster ARM64 support for a couple more days, but Apple’s switch puts them under long deserved pressure. A nice Linux/Android/Chromium hybrid ultrabook running whatever Office could get things moving quicker… at least I hope that, because I’d never want to be forced into the bitten Apple…. by these corporate decision makers I see already twitching.

    No chance I’d ever let a new Apple into my home: The ][ was the last good one they made.

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