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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  • rburnham - Thursday, December 20, 2012 - link

    One thing about Windows 8 that continues to bug me is the way that settings are split into two areas. Some settings can be handled from the Start screen, while others take you to the desktop Control Panel. If Microsoft is so keen on this new UI, why not take the entire Control Panel and make it a Modern UI component? I get that they are trying to appeal to touchscreen and desktop users, but merging the settings into one area would help alleviate the schizophrenic feel of the OS a little bit.

    This is a great review, especially since I have this exact Acer tablet on the way from Newegg. My hope is that I will spend most of my time in the Modern UI, and occasionally fire up desktop software. I am hoping it will be fast to handle some older games, like Icewind Dale, and some non-CPU intense software, like the Zinio desktop app (where I can access publications that the mobile version cannot access). It's going to be an interesting experiment.

    My other concern with this tablet is that it is so new, there is a very limited selection of accessories. Specifically, I am having trouble finding some sort of "gel skin" case for this tablet. There are some generic fold out tablet cases, but those are bulky.

    By the way, I had hoped to get an AMD Windows 8 tablet, but where are they? I love AMD, but I have to buy based on my needs and what's available, and right now Intel has the only real x86 solution for Windows 8 tablets.
    Reply
  • name99 - Thursday, December 20, 2012 - link

    "The power adapter itself isn’t anything remarkable, however Acer did use a nifty removable plug that easily twists on/off. The W510 only ships with the plug for whatever region you purchased it in so I’m not sure how useful this feature is, but it’s nice to see design innovation from Acer here."

    Just for the record, this is not new. Apple's power supplies for MacBooks have done this for, I don't know, 8 years or so. The power supply has a core that is common, and a regional plug that can be slipped on or off. See here:
    http://eshop.macsales.com/images/Items/APLMA538LLB...

    iPad power adapters are the same. iPhone/iPod are not, I expect because they are so small that they are basically the size of the dongle that would plugin to the socket, so modularizing them this way would basically double their size.

    I've no idea if this is original to Apple or not, but it's certainly not original to Acer.
    Reply
  • secretmanofagent - Friday, December 21, 2012 - link

    I don't think you understand the mechanism. Apple uses a friction fit with a straight downward motion. The connector that Acer uses rotates on, which you can see in the picture the directions to operate. All of the other adapters I've seen (including miscellaneous ones over the years) have been similar to Apple's, usually with a mechanical clip. Acer's method is innovative, but I'm not sure what advantages are offered by it. Reply
  • lorribot - Thursday, December 20, 2012 - link

    It's things like that 11GB recovery partition that show how far MS have to go in the light weight sector. The 13 GB for Windows, which will bloat massively with patches and installs is another example of them playing the wrong game.
    My windows & folder is a typical 21GB add to that a 11 GB recovery partition and that leaves nothing for user docs or programs on a 32GB model.

    It would make more sense to stick the recovery partition on a 16GB USB stick or SD Card and use that to recover the system should the need arise and give back some of the expensive internal storage space to the user.

    Windows 8, good first attempt but wait for Windows 9 when they fix all the things they didn't have time for and realise two into one doesn't go.
    Reply
  • name99 - Thursday, December 20, 2012 - link

    Yeah, I was amazed by that 11GB figure.

    As a point of comparison, the OSX recovery partition is 650MB in size.

    Now it it possible that the Win8 recovery partition does more (as opposed to "has more to do [because there are more things that can go wrong]"; I'd be interested in an informed comparison of the two, and a dissection of just what is taking up all that space.

    Is it sheer incompetence (for example including 64 bit binaries on a 32bit system)?
    Is it including every human language on earth?
    Is it because no-one bothered to make an effort to include only the bare minimum OS+support frameworks (as opposed to including the AV subsystem, and .NET, and fifteen ways to talk to a database, and support for MS Office, etc etc etc)?
    Reply
  • kyuu - Thursday, December 20, 2012 - link

    They do need to do something about the humungous recovery partition, but... you can put the recovery partition on a thumb drive or other removable media and free up that 11GB, if I'm not mistaken. Reply
  • secretmanofagent - Friday, December 21, 2012 - link

    It's an incorrect comparison, as the restore for OS X requires an Internet connection.

    "In order to reinstall OS X Lion or OS X Mountain Lion, you will need to be connected to an Ethernet or Wi-Fi network."

    "The OS X download is about 4 GB large;"

    http://support.apple.com/kb/HT4718
    Reply
  • name99 - Friday, December 21, 2012 - link

    Yes and no for the Apple restore.

    The recovery partition has tools that can do a bunch of things, for example run a fsck on the boot drive. If your problem is the sort of thing that can be fixed by fsck, ie some localized damage to the file system, then you will not need the internet connection.

    You will need it (sortof) if you want to reinstall the OS.

    If MS have the entire OS in their recovery partition, the size makes more sense, but seems more than a little foolish --- wasting so much fast expensive flash when you could ship a cheap USB stick.

    In the case of Apple, it is fairly trivial when you first download/install Lion or Mountain Lion to burn a copy to a USB stick, and to use that copy if you don't have an internet connection (or have a slow connection, or pay per MB downloaded, or whatever).
    I do think it's less than ideal that they don't include a USB stick of the OS with new machines (they did with the first few iterations of MacBook Air), but it's possible that their numbers tell them that pretty much no-one ever needs to reinstall the OS --- the tools of the recovery partition are acceptable for pretty much all problems. Certainly in my experience that's been true, for both my and friend's machines. I have no comparable experience with Windows.
    Reply
  • MonkeyPaw - Thursday, December 20, 2012 - link

    Microcenter has the 32GB model on sale for $399, so I took a chance. Your review pretty much matches my conclusions as well. It's generally a nice device, CPU performance is good, etc. The major disappointment for me was terrible game performance. I had lag and choppiness playing Solitaire! In late 2012?! I want to like Windows 8, but to have a card game take up almost 100MB of precious eMMC capacity is just sad. Until storage default size balloons significantly, it's hard to get on board with MS right now.

    Another thing MS needs to work on is the keyboard auto-correct, or the lack of it. The onscreen keyboard offers no assistance, and text selection is a nightmare. In IE, I could never select text, as double tapping just kept zooming in and out. It was quite frustrating.

    I found the camera and its respective app to be horrible. Not just bad, unuseable bad.

    I really really wanted to like the W510, but I ended up exchanging it for a Transformer Infinity. I am much happier with it.
    Reply
  • kyuu - Thursday, December 20, 2012 - link

    As far as the text selection thing goes, if it's anything like Windows Phone, you don't double-tap to select things (as you noticed, that zooms). You long-press instead. It's a little odd if you're in the habit of double-tapping from iOS/Android, but it works just fine for me on my Windows Phone. Reply

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