Home > 5th Edition, Rant, Symbian^3 > Symbian OS and Nokia’s CPU choice sidenote

Symbian OS and Nokia’s CPU choice sidenote

Not a long blog post but more of a notification for all the Symbian and N8 users out there.

Symbian as an OS does something that few if any mobile OS’s out there do. It allows the networking (cellular) stack and applications to run on the same CPU. Ever wondered why your phone lags HARD when downloading emails (if set to headers only) and opening applications? This is it.

Worse still is the fact that current Symbian^3 devices still use ARM11 processors, we have the issues of a rather short processor pipeline and an in-order, single issue execution method. Meaning that the CPU can only handle a very few number of inputs per unit time in addition to the fact that it MUST complete each instruction before moving on to any instruction behind it, does not allow other instructions leap-frog it in the execution pipeline regardless of how long the instruction takes AND is only able to process one set of instructions at a time.

In layman’s terms, your email has to finish downloading before it can render AND you can’t interact with the OS before this happens either. Although S^1 didn’t support ARMv7 architecture well (Cortex A8 etc), S^3 does. Makes you wonder if Nokia made the decision to stick the ARM11 in there and why if they did that, they didn’t go for a dual core approach using an applications core and a networking core a la OMAP or a simply better CPU with a dual issue pipeline like a Cortex A8.

Ah well, if you make your bed, you gotta sleep in it.

Sidenote: Anandtech has a pretty awesome crash course in CPU architecture to help us not so smart people understand the differences between ARM11 and Cortex A8 in addition to CPU architecture and design.


Categories: 5th Edition, Rant, Symbian^3
  1. VV
    November 16, 2010 at 6:56 pm

    I think Nokia in its quest to cut production costs leave out some important parts that would make super smartphones.Like why not more ram or a more a powerfull cpu?Symbian may be efficient but c’mon…I really hope they go all the way out with the Meego device and use the latest tech inside (processor especially).Regarding battery life-current battery technology is what it is.But that doesn’t seem to stop Android devices from coming out and people buy them like crazy.C’mon Nokia,I know you can.Give us your REAL best! 🙂

    • Dave
      November 16, 2010 at 8:51 pm

      Consider that the N900 was running a Cortex A8, there’s no sense in Nokia going back for the N900 successor.

      • Andre
        November 16, 2010 at 8:55 pm

        They likely had huge stocks of ARM11’s and no A8 in addition to cost cutting.

  2. the_ultimate111
    November 16, 2010 at 8:14 pm

    It is not very correct to put this in such a way. Actually there is a DSP for interacting with GSM and UMTS networks in each Symbian device.
    I just had my e-mails downloaded through GSM GPRS, when palying Raging Thunder 2 wit absolutely no lag!
    There is no such problem, as you are drawing!

    • Andre
      November 16, 2010 at 8:19 pm

      Doesn’t change the fact that rendering HTML which is CPU intensive process can’t occur at the same time as any interaction with the device. 🙂

      A dual issue CPU would STILL be better. I’m also pretty certain that a significant bit of networking is handled by the CPU.

      • btdt
        November 16, 2010 at 11:18 pm

        I think the old browser being slow is pretty much based on the fact that it doesn’t use the broadcom’s gpu acceleration.

        • Andre
          November 16, 2010 at 11:22 pm

          It can’t unless we’re talking about putting the data on the screen as opposed to helping to render the HTML.

          The primary issue with the browser is the Javascript performance and little else

  3. mja
    November 16, 2010 at 8:57 pm

    Maybe older HW was chosen for the current S3 devices so that price for the cheapest (C6-01) could be kept low but at the same time minimising fragmentation (all S3 devices will be able to run the same programs as they have identical CPU:s, GPU:s and display resolutions). They’re all mass-market devices. Us geeks will get our MeeGos soon 🙂

    • Andre
      November 16, 2010 at 9:00 pm

      While I do understand that, it’s still a bottleneck and a problem for quite a few people.

      MeeGo can’t come soon enough. I simply hope I’m not underwhelmed or disappointed.

  4. chfyfx
    November 16, 2010 at 9:03 pm

    Honestly, I do not think the CPU is the reason for this lag. IPhone had ARM11 before and did not lag a bit.

    • Andre
      November 16, 2010 at 9:04 pm

      CPU on iPhone only handled apps not apps and networking.

      • chfyfx
        November 16, 2010 at 10:06 pm

        i do not remember the original IPhone had a second CPU to handle networking?

        • Andre
          November 16, 2010 at 10:21 pm

          It likely had one.

          OMAP for example has one.

          • chfyfx
            November 16, 2010 at 10:36 pm

            the IPhone 3G uses ARM 11 412 MHz, PowerVR MBX-Lite graphics

  5. Cod3rror
    November 16, 2010 at 10:57 pm

    If Nokia uses ARM11 in their mid-high end phones in 2011, they deserve to fail… enough to this cost cutting, innovate and create something good and you won’t have to cut costs and go into lower and lower segments to run away from your competitors.

    • Keith
      November 16, 2010 at 11:01 pm

      Well, if you want something innovative and good, wait for MeeGo – True high-end platform; No compromises. Symbian is for low/mid end. It is concerned more about the price.

      • chfyfx
        November 16, 2010 at 11:04 pm

        in fact, i find his opinion is kind too negative and trollish

        • Andre
          November 16, 2010 at 11:23 pm

          I’m being honest though :-|.

          • chfyfx
            November 16, 2010 at 11:53 pm

            Understood. but N8’s hardware is not bad at all… Nokia is not doing it right on the software side. Please do not go back to the A8 vs ARM11 thing. ARM11 at 680Mhz is enough for Symbian. If you think the email is slow, try the webversion directly… Something is wrong on the software side for S^3. I’d say they did blow it here.

          • GordonH
            November 17, 2010 at 4:59 am

            The root culture of symbian is software optimization. Surely a updated processor should help any application perform nicely.
            I feel the email client needs better software and a bit more time to mature.

  6. Andre
    November 16, 2010 at 11:01 pm

    chfyfx :

    the IPhone 3G uses ARM 11 412 MHz, PowerVR MBX-Lite graphics

    That’s only part of the chipset. Furthermore I’m pretty sure that Symbian is the ONLY OS that allows applications and networking on the same CPU at the same time.

  7. Andre
    November 16, 2010 at 11:57 pm

    chfyfx :

    Understood. but N8′s hardware is not bad at all… Nokia is not doing it right on the software side. Please do not go back to the A8 vs ARM11 thing. ARM11 at 680Mhz is enough for Symbian. If you think the email is slow, try the webversion directly… Something is wrong on the software side for S^3. I’d say they did blow it here.

    No arguments there

  8. Andre
    November 17, 2010 at 5:02 am

    GordonH :

    The root culture of symbian is software optimization. Surely a updated processor should help any application perform nicely.
    I feel the email client needs better software and a bit more time to mature.

    I can almost assure you that with an ARMv7 processor that this thing would FLY in everything except the browser. Most people would be wondering how it gets that much juice. Especially as it wouldn’t have to be clocked as high to get the greater performance.

  9. alex68
    November 17, 2010 at 7:37 am

    ARM CHIPS are proven more PM efficient. There must be reasons why Nokia dumped Cortex A8 after N900. I could not believe Andrea’s ARM stock theory.

    • Andre
      November 17, 2010 at 5:50 pm

      Symbian wasn’t written for A8’s until S^3 and they needed to have a stock of processors for them to build devices. If you were uncertain on the ability of an OS to work well with your processor choice, you take the safe option and stick with something that you KNOW works.

  10. kmmbd
    November 17, 2010 at 5:10 pm

    I don’t know whether people miss this fact or just tend to overlook it, but the Broadcom chipset inside N8 and the likes is actually a multimedia processor, and it consists of a DSP, IP, GPU. Thus technically the ARM11 application should be offloaded of any signal processing. The 5 stage pipelining structure is a problem though, but you have to code specifically for 8 stage pipelining structure (A8). So if the O.S. is coded efficiently for handling processes, the performance gain shouldn’t be too big. But anyways, A8 is a much better choice than ARM1176.

    • Andre
      November 17, 2010 at 5:53 pm

      A8 has a dual issue pipeline AND a longer pipeline. That’s a big difference. Only issue with that is the fact that it doesn’t support out-of-order execution which means that if a process is in the pipeline and stalls because of I/O problems you stall a ton of other instructions behind it.

      Dual issue pipeline with an intermediate length pipeline is ideal. Hence why I wish to see Cortex A9’s in Nokia’s upcoming MeeGo devices

      • November 18, 2010 at 10:41 am

        Andre, what does duel-issue pipeline mean?

        • Andre
          November 18, 2010 at 3:15 pm

          Means that it can process two parallel streams of instructions at any given time-point.

  11. Alexander Sinco
    November 20, 2010 at 4:12 am

    My old n95 has an omap SoC with dual core processor and a powervr lite graphics so not all symbian phones runs on a single cpu SoC.

    • Andre
      November 20, 2010 at 7:27 am

      The N95 and N82 benefited hugely from that as I’m sure you’re well aware.

      The fact is, they were an aberration and not the norm

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