CPU Performance

The heart of the Clover Trail advantage is really Intel’s two 32nm Saltwell Atom cores that are integrated into the Cloverview SoC. Each core is Hyper Threaded making the machine a 2 core, 4 thread beast similar to what we’ve seen from Intel’s other dual-core processors for years now. Despite the 32nm process, these Saltwell cores are direct descendants of the original Bonnell Atom core, first built at 45nm back in 2008. The fact that in five years the Atom core has only progressed by a single process node tells you a lot about how much of a priority this architecture has been for Intel. To Intel’s credit, Cloverview is built on an SoC process at Intel’s fabs that’s slightly different from the standard process used for the Core line of processors. Intel’s low power SoC process roadmap has historically lagged behind the high performance roadmap, although at some point in the not too distant future Intel expects these two to happen in near lockstep.

Medfield vs. Clovertrail
  Intel Atom Z2460 Intel Atom Z2760
Platform Codename Medfield Clovertrail
OS/Platform Target Android Smartphones Windows 8 Tablets
Manufacturing Process 32nm SoC (P1269) 32nm SoC (P1269)
CPU Cores/Threads 1 / 2 2 / 4
CPU Clock up to 2.0GHz up to 1.8GHz
GPU PowerVR SGX 540 PowerVR SGX 545
GPU Clock 400MHz 533MHz
Memory Interface 2 x 32-bit LPDDR2 2 x 32-bit LPDDR2

The fundamental architecture of each Atom core hasn’t changed. This is still a 2-wide in-order machine with a bunch of power and performance efficiency tricks that make it hit much higher than you’d otherwise expect. As you’ll see in the benchmarks to come, this five year old Atom architecture is still faster than every single ARM based core on the market today with the exception of the Cortex A15. Hampered mostly by really inefficient software and a lack of good platforms, Atom never really had the opportunity to shine in the past. Even with Windows 8 things are better but still not perfect for the soon-to-be-replaced core.

Each core features its own private 512KB L2 cache and can clock up to 1.8GHz. These cores could technically support 64-bit operation, but Intel specifies them as supporting the 32-bit x86 ISA. Windows 8 with Connected Standby (S0ix baby) support only currently exists in a 32-bit version, and Clover Trail is only designed to support Windows 8 at this point which is why these are effectively 32-bit cores.

Backwards compatibility is a major selling point for the Clover Trail platform as being able to run existing Windows applications is something no competing ARM platform can offer. There are two limitations however: 1) Keep in mind that this is still an Atom based SoC, so just because you can run (virtually) all applications it doesn’t mean they will perform well, and 2) These Atom cores only support SSE1/2/3/3S, the newer extensions to x86 aren’t supported (no SSE4 or AVX). The latter isn’t too big of a deal given that those extensions are rarely required for older applications, but it’s a distinction worth noting.

Despite looking at lot like Intel’s Medfield platform, Clover Trail does differ in some fundamental ways. Intel doesn’t have a lot of documentation about this but the memory controller on the Cloverview SoC has been significantly improved over Medfield. It better supports prioritizing GPU accesses to main memory, which in turn helps deliver a very smooth Modern UI experience in Windows 8. The Cloverview/Clover Trail memory controller enhancements will make their way into Medfield’s successor on the smartphone side, as well as future derivatives of Intel’s Atom for tablets.

I mentioned this in our initial Clover Trail analysis piece, but the SoC doesn't support SATA - only eMMC. Only USB 2.0 is supported as well.

As we make our way into 2013, at least on the Windows side of things, I'll be able to move away from js based performance comparisons between tablets. For now, we start off with some of the latest JavaScript tests we've been using in our mobile reviews. All of these were run in Modern IE10 on the Windows devices. I threw in some of our iPad 4 and Nexus 10 for comparison:

JavaScript Performance
Time in ms (Lower is Better) Kraken SunSpider RIA Bench Focus
Acer W510 (Atom Z2760 1.8GHz) 33220.9ms 730.8ms 3959ms
Microsoft Surface (Tegra 3 1.3GHz) 49595.5ms 981.1ms 5880ms
Samsung ATIV Smart PC (Atom Z2760 1.8GHz) 33406.0ms 721.3ms 3752ms
Apple iPad 4 (A6X) 19086.9ms 834.7ms -
Google Nexus 10 (Exynos 5 Dual) 11146.0ms 1384.1ms -

Although CloverTrail manages a win over all platforms in SunSpider, Kraken paints a different picture. In the case of the iPad 4 it's likely showing us browser performance superiority, while in the case of the Nexus 10 it's a combination of that and a simply faster pair of CPU cores.

Principled Technologies, apparently featuring some of the same folks who were responsible for building the old Winstone benchmarks from over a decade ago, actually put out the first cross platform Windows RT/8 benchmark with some help from Intel. Despite Intel’s influence the test appears to have no native code, instead relying on just a heavy workload of large images and videos for its tests.

TouchXPRT 2013
Time in Seconds (Lower is Better) Photo Enhance Photo Export Video Transcode MP3 Transcode Photo Slideshow Creation
Acer W510 (Atom Z2760 1.8GHz) 205.83s 73.0s 52.07s 96.02s 85.31s
Microsoft Surface (Tegra 3 1.3GHz) 306.12s 116.36s 87.27s 160.99s 125.06s
ASUS VivoTab RT (Tegra 3 1.3GHz) 312.14s 109.89s 89.69s 155.84s 122.65s

The PT folks also put together a suite of HTML5/js tests, once again giving us the opportunity to test cross-platform performance. As these tests are run in the browser, there's good opportunity for browser optimizations to play a role here as well as platform performance:

WebXPRT 2013
Time in ms (Lower is Better unless otherwise noted) Overall (higher is better) Photo Effects Face Detection Stocks Dashboard Offline Notes
Acer W510 (Atom Z2760 1.8GHz) 220 2437.2 ms 2590.3 ms 1091.5 ms 1832.4 ms
Microsoft Surface (Tegra 3 1.3GHz) 168 2790.7 ms 3482.1 ms 1696.3 ms 2288.1 ms
Apple iPad 4 (A6X) 182 4331.2 ms 4136.8 ms 786.0 ms 1942.6 ms

It doesn’t really matter where you turn, the CPU side of Clover Trail is clearly ahead of anything we’ve seen thus far in the Windows RT camp. Modern UI performance is great, clearly better than Surface, but the Windows 8 desktop experience falls short. UI performance can be sluggish in desktop mode. Scrolling through Control Panel animates at < 30 fps, the same goes for highlighting a group of icons on the desktop. Moving windows around tends to be pretty smooth however, which makes me wonder how much of the UI performance issues are driver related.

On the CPU side of things, you have to keep in mind this is still an Atom based platform. Although things have improved since the original Atom, we’re still talking about a fairly old architecture. Although you can run Photoshop or 3dsmax on here, I wouldn’t recommend it. As with the old netbooks, whether or not Atom is enough depends mostly on what you’re doing.

All of the Office 2010 applications ran wonderfully on the W510. They all launched reasonably quickly and were responsive. Outlook, a major component missing from the Windows RT experience, had no problems running on the W510. The experience does suffer the moment you try to run something truly CPU intensive (by modern notebook standards), but for light office work the W510 excels.

The high CPU utilization under Word 2013 does still exist even on Clover Trail:

I ran our Excel MonteCarlo simulation script on the W510 to get an idea of how a hefty Office workload would fare on the tablet. The result was surprisingly decent thanks to hardware support for 4 threads, but still much slower than a modern CPU:

Microsoft Excel 2007 SP1 - Monte Carlo Simulation

To really put the W510's performance in perspective I compared it to a handful of notebooks:

PCMark 7 - PCMarks

Better performance than AMD's original Brazos platform isn't bad, but in the grand scheme of things you're looking at a much slower system than anything Core based. The W510 comes surprisingly close to the Llano based Toshiba P755D, but I suspect a big part of that is the storage solution. The blessing and curse of the W510 is that it does use solid state storage, so performance will never be as bad as the old netbooks that used 5400RPM hard drives. The solid state storage comes in the form of an eMMC solution, which doesn’t do a great job of delivering high random IO performance.

The Display GPU Performance
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  • MonkeyPaw - Friday, December 21, 2012 - link

    I sampled the 32GB version not long ago.There was no recovery partition (they give you 4 DVDs), but when it's all said and done, about half the space is consumed by the base install. Once you add a modest selection of media and a few MS apps (which can be rather large), you are looking at a few GB of free space remaining.
  • skiboysteve - Friday, December 21, 2012 - link

    Do people really need the installed paid for versions of office? The free online web apps are completely amazing. Way way better than google docs... They are just about full versions of office. Only thing I could think of is for airplane trips
  • zeo - Monday, December 31, 2012 - link

    Only the RT version has Office included by default, and it's the more basic Home and Student 2013 RT version, regular W8 depends on the system maker as to whether a copy of Office will be included or not... Like, I believe, Lenovo offers full Office with the Lenovo Thinkpad Tablet 2 for example.

    RT though is a bit stripped down from W8 and so is a bit smaller install than regular W8/Pro, even with Office included.

    Regular W8 tablets though are suppose to start with 64GB drives, they just offer 32GB for lower entry price point and it's only the RT tablets that are suppose to start with 32GB.

    This is mainly due to the pricing structure used by most tablet makers, most charge for capacity even though the actual capacity doesn't cost the price difference. Like the $249 Nexus 7 doesn't cost $50 more than the $199 Nexus 7 to add that extra capacity, but this is how they improve their profit margins when offering higher specs and can afford to lower profit margins for the lower spec versions.

    All Windows tablets though should offer Micro/SD, though for now you can't install apps anywhere but the main drive but you can put just about everything else on the memory card for extra capacity.

    While higher end tablets should offer drives up to 128GB and some will offer hard drives in the docks, like the Asus Vivo Book has a 500GB HDD in the keyboard dock.
  • CaptchaIsEvil - Friday, December 21, 2012 - link

    So this is what it's like to depend on far flung "OEMs" to build a product that will attract an audience.

    MS is depending on OEMs who use weak drivers resulting in poor user experience and that build substandard hardware.

    Just like with Android, Samsung will be the only OEM to step up to the plate and dedicate the resources to compete in the big leagues. It won't be Acer and it won't be the commoditizers at HP or DELL (parts bin assemblers).

    MS better hope it happens soon.
  • zeo - Monday, December 31, 2012 - link

    Weak drivers are a issue, but Intel will be moving back to a GMA based on their own technology instead of Imagination's with the 22nm ATOM updates.

    There may still be some driver issues but support for their own hardware is much better and we'll see a return of full 64bit and Linux support.

    The actual GMA is suppose to be based on the Ivy Bridge HD4000, just scaled down from 16 execution units to 4, and that should mean better developed drivers from the start as well.

    It'll just be either late Q3 or around Q4 2013 until we see products based on the update start to come out.
  • nofumble62 - Friday, December 21, 2012 - link

    fast, run everything, and have lot of storage.

    Tablet is a fad, and will fade away.
  • kyuu - Friday, December 21, 2012 - link

    How's the weather over there in Denial Land?
  • nofumble62 - Friday, December 21, 2012 - link

    Great- warm and toasty over my i7-3770.
    In the drawer, there is an iPad3 and a Kindle Fire. They are nice to play with for a short while, but I am now back to my 24" IPS and keyboards.
  • aliasfox - Sunday, December 23, 2012 - link

    And here's the alternate scenario: I'm on my iPad1 At my parents' house, and after the second day of regular use I'm still at 42% battery life, and I'm doing the same thing as you, commenting on a forum.

    Is it slow as heck? Yes. Is it useful for a whole lot besides for web surfing, videos, and short writing like this? No, not really. Is web surfing, videos, and short writing like this a significant portion of my daily web life? Yes. Do I appreciate the fact that I can get two and a half days of usable battery life in a package about half the weight of an ultrabook? Absolutely. Have regretted I buying and using this for the past two and a half years? Aside from abysmal resale value, not at all.

    My Mac Pro doesn't get much use besides for Netflix watching on my TV, so for my usage scenario, I'm cool with a tablet. I'll throw in shipping cost if you want to send me your iPad3 though, I'll give it a good home.
  • Death666Angel - Saturday, December 22, 2012 - link

    Hey!
    Good article. Just wanted to say that the charger connector is pretty much similar (the same?) my Travelmate 8172 has (just in white whereas mine is in black). On that charger, I can use it to set the orientation of the charger, it helps in crowded sockets. And guess it might save Acer a few cents of cost. Anyway, I like it a lot. :D

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