It's Really Not Qualcomm's Fault

We've established that webOS has been and could be ported to different SoCs from different vendors – there's nothing tying it irrevocably to Qualcomm. The next is a discussion of the performance delta that existed because of differing hardware between tablet vendors. The Next Web wrote a story today claiming that webOS could run over 2x as fast on an iPad 2 than on an HP TouchPad. The claim gets even more interesting:

"With a focus on web technologies, webOS could be deployed in the iPad’s Mobile Safari browser as a web-app; this produced similar results, with it running many times faster in the browser than it did on the TouchPad."

I'm going to ignore the whole "because it's webOS it can run in a web browser" argument but let's get to the performance discussion. While webOS and Mojo do make substantial use of JavaScript, CSS, and HTML5, that doesn't necessarily mean the entire OS itself can be a web application. Don't forget the Palm PDK as well, which runs much closer to metal than the Mojo SDK.

Anyhow, the TouchPad uses Qualcomm's Snapdragon S3 APQ8060. It has two Scorpion cores running at 1.2GHz, a shared 512KB L2 cache and a dual-channel memory controller. In the TouchPad there's only a single 1GB DRAM on board. It's unclear if there are two DRAM die on that package or not, so whether or not the SoC is actually given full access to 2 x 32-bit LPDDR2 devices is unclear. The CPU cores are in-order and feature a pipelined FPU and NEON unit. On the GPU side the APQ8060 uses Qualcomm's Adreno 220.

If this hardware sounds familiar to you it's because it's the modem-less version of the MSM8x60, the same SoC used in the HTC Sensation and the EVO 3D.

The iPad 2 uses Apple's A5 SoC manufactured by Samsung. It has two ARM Cortex A9 cores, a 1MB shared L2 cache and a dual-channel memory controller. The A5 in the iPad 2 comes in a PoP (Package-on-Package) configuration with the DRAM stacked on the SoC die. Although it's physically unclear whether both channels are populated, the Samsung DRAM part number on the A5 indicates a PoP stack with two DRAM devices. In other words, the A5 is running in dual-channel mode. The CPU cores are out-of-order, feature a pipelined FPU and NEON unit. Imagination Technologies supplies the PowerVR SGX 543MP2 GPU in the A5.

From a CPU standpoint, Apple has a performance advantage at the same clock speed, but Qualcomm runs its cores at a higher clock. NVIDIA claimed that the move to an out-of-order architecture in the A9 was good for a 20% increase in IPC. Qualcomm has a 20% clock speed advantage. In most situations I think it's safe to say that the A5 and the APQ8060 have equally performing CPUs.

Apple does potentially have a memory bandwidth advantage as it's unclear the memory configuration of the TouchPad. I did wonder if this might be a reason why UI transitions were so slow on the TouchPad. In order to deliver a smooth UI you need good GPU acceleration built into your OS and you need sufficient memory bandwidth for the screen. At 1024 x 768 you need 180MB/s of memory bandwidth to render a UI at 60 fps. That's assuming no overdraw or multi-pass blending effects. With only a single LPDDR2-667 channel there's only 2.7GB/s of theoretical memory bandwidth. In practice you generally get 80% of peak theoretical memory bandwidth, that takes us down to 2.1GB/s. If we assume webOS was really inefficient in drawing its UI and needed 7x the bandwidth per frame, that still leaves us with 840MB/s of bandwidth available for the rest of the SoC. Assuming the CPU cores aren't doing anything, that's enough to provide a smooth, 60 fps UI. Start taxing those CPU cores and their bandwidth demands could go up to a few hundred MB/s, perhaps even more. Let's not even mention what happens if the GPU starts cranking away.

Now if we assume that webOS is super efficient, then even a single LPDDR2 channel is more than enough to deliver a high speed UI. In my calculations above I assumed a 7x increase in memory bandwidth requirements per frame. If we knock that down to 4x we nearly double the amount of memory bandwidth available to the rest of the SoC.

My point here is that the Qualcomm hardware is technically fast enough to deliver a smooth UI in webOS. The problem wasn't the hardware.

As far as CPU performance goes, here's a graph comparing the Tegra 2 based Galaxy Tab 10.1 to the A5 based iPad 2 in Sunspider 0.9:

SunSpider Javascript Benchmark 0.9

Granted this test measures the entire hardware and software stack (browser, OS) and does show a ~2x performance delta between the TouchPad and iPad 2, but it shows that it's physically possible to build a tablet that has performance similar to the iPad 2. Furthermore, we've already shown that NVIDIA's Tegra 2 performs similarly to Qualcomm's dual-core SoC in other situations. Completing the circle it's safe to assume that at least from a CPU standpoint, Qualcomm's APQ8060 wasn't the factor holding back the TouchPad, it was software.

The only area where the iPad 2 could conceivably be 2x the speed of the TouchPad due to SoC hardware alone is in GPU performance. However the claims above say the performance advantage was demonstrated in a browser window and not in a cross-platform OpenGL ES 2.0 game.

These days Qualcomm's high end dual-core SoC is comparable to TI's and NVIDIA's. Each platform has its advantages but I find it very difficult to believe that Qualcomm was somehow responsible for the poor performance of the TouchPad. 

It's Not Qualcomm's Fault webOS Needed Work
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  • seapeople - Saturday, August 20, 2011 - link

    I think it's pretty clear that ANAND has sold out to the INTARWEB because of how quickly he used it to past ALL HIS ARTICLES. I know this because I've been reading lots of OTHER TECH BLOGS and they are much more CRITICAL of NON-INTARWEB communication!

    I mean, Anand hasn't even mentioned the Verizon strike that's been going on. Should he mention such a major issue in telecommunications? Of course not, it's because he's in the INTARWEB DIRTY MONEY BUSINESS.
    Reply
  • ssnova - Sunday, August 21, 2011 - link

    "I mean, Anand hasn't even mentioned the Verizon strike that's been going on."

    If you've been an avid Anandtech reader, then you would know they don't waste their time on politics and issues of that nature. If you want that kind of "intarweb" "buzz" then that's what Dailytech is for. Anandtech has always focused more on technical articles, educating the reader, breaking things down in an informative manner.

    I vouch for Anandtech because I've been an avid reader of their articles since 2003, and though no review is perfect, something that I always respected Anandtech for was their thorough in-depth breakdowns of subject matters and drawing logical conclusions(as best as possible, drawn from the subjective/objective data). This goes generally for all their veteran staff, which I haven't seen some of them post articles in a while.

    ...On a random note, whatever happened to Kristopher Kubicki? I don't even see Dailytech posts by him anymore?

    Any how... again... the stuff on here is just a technical breakdown with some insight, perhaps it could have been titled better, but after reading the article I see no reason to try and please the crowd when spitting it out in your own way.
    Reply
  • WeaselITB - Monday, August 22, 2011 - link

    @ssnova

    I think you need to get your sarcasm-meter checked ...

    -Weasel
    Reply
  • jaysns - Sunday, August 21, 2011 - link

    I like this kind of article when you see the internets abuzz, and by that I mean the bigger blogging sites, with misinformation. A lot of sites were reporting on this and a nice little write up explaining why it was untrue and didn't even make sense is a good thing. Not everyone knows these things, and even I who understands this, and is well read up enough at least to notice the BS that engadget and others were putting out, enjoyed reading this. This is my favorite tech site. Just wish you guys posted more :p. Keep up the good work. Reply
  • Zoolookuk - Sunday, August 21, 2011 - link

    I can't ever remember thinking an Anand article was way off target, but this one is. You dedicated 3 pages to telling us this wasn't a hardware issue, and then showed a benchmark illustrating the TouchPad was half the speed of the iPad 2, which has fairly modest hardware specs. If you reviewed the latest AMD chip and showed it at half the speed of a 6 month old Intel processor, you wouldn't claim it has 'similar performance'. I really don't get that.

    The irony here of course isn't you letting a 200% performance gap go, it's that NO ONE is saying the reason the TouchPad bombed is because of overall performance. Leaping to it's defense seems a little weird.

    I don't even agree that the issue is WebOS - it's a fine operating system that had a lot of promise. The issues were:

    - Terrible design and build quality (it looked and felt like a budget iPad)
    - Non-existant or poor marketing (Glee? Really?)
    - No integration within anything meaningful. Android has the entire Google eco system, while Apple has iTunes and virtually everything else

    Maybe read this too early on a Sunday morning, but you seem to be trying to prove a point that just isn't there.
    Reply
  • ViRGE - Sunday, August 21, 2011 - link

    "Maybe read this too early on a Sunday morning"

    I think that would seem to be the case. The only argument Anand is making is that the poor performance you see - "then showed a benchmark illustrating the TouchPad was half the speed of the iPad 2" - is due to the software and not the hardware. That still makes the TouchPad a lousy device, but the purpose of the article is to establish why.

    And someone did say the problem was the TouchPad's performance: http://thenextweb.com/apple/2011/08/19/hp-tested-w... . That's the article that spurred this one, since the idea that a dual-core A9 is twice as fast as a dual-core Snapdragon (clocked 20% higher) is silly.

    Snapdragon ~= Tegra 2 (source: many, many AT phone reviews)
    Tegra 2 ~= Apple A5 (source: AT Galaxy Tab 10.1 review)
    QED: Snapdragon ~= Apple A5

    Hence the idea that the iPad (Apple A5) platform being twice as fast as the Snapdragon platform is silly. The software stinks, the hardware is fine.
    Reply
  • tipoo - Saturday, December 10, 2011 - link

    No, he said that it had similar performance to the Tegra 2, then showed the huge performance difference between them, showing that its a software thing and not a CPU thing. Reply
  • sirsoffrito - Sunday, August 21, 2011 - link

    I was already suspicious of these other websites claiming Qualcomm's incompetency. It seemed pretty hard to believe given the amount of inefficient bloat HP's Windows machines come with. In such a competitive market as tablets now, manufacturer's have exactly *one* shot to prove they are up to snuff, and I can't say I've been terribly impressed with HP's build quality hardware wise in recent years, much less all the software they try and foist upon people. What's funny is that the software is so incredibly important and is often the most ignored. A well optimized program can make all the difference in the world. People respond to a clean, snappy interface; hence Apple's success. Reply
  • superccs - Sunday, August 21, 2011 - link

    SO essentially you are saying that this device has legitimate hardware, just poor implementation...?

    Wouldn't this make this device a steal for rooters and modders?
    Reply
  • Zoolookuk - Monday, August 22, 2011 - link

    The WebOS team apparently experimented with their OS on the iPad2 hardware, where it ran 'twice as fast' .

    http://www.appleinsider.com/articles/11/08/22/hp_r...
    Reply

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