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ARM Cortex-A15 vs. NVIDIA Tegra 3 vs. Intel x86

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  • #41
    Originally posted by artivision View Post
    No, no, no. Don't take all those for real. They measure the entire board that is different from smartphone boards. My personal tests only with a cpu say this: A9-single (13m transistor) @2ghz 65nm-HP =950mWp. The same at 45nm-HP =500mWp, and 40nm-LP =350mWp. The same at 28nm-LPE =200mWp, and for dual core 400mWp. If we assume that an A15 consumes 2x as it is, and 3x with the 32nm-Samsung, then 2.5Wp for the entire SOC with graphics and without memory its fine. For example the dual A15 inside the new iPhone what do you thing it consumes? If it was 5Wp without memory then the device will power off in 15 minutes full use.
    Iphone has a 6whr battery, that can last for one hour if soc+screen power is 6w.


    • #42
      Could you test with GCC 4.7? You can get it from this PPA: ppa:ubuntu-toolchain-r/test It works on Chromebook and should work on all the other platforms. I saw some pretty substantial performance gains, around 15% in the one thing I tried.

      Originally posted by Tempestglen View Post

      Samsung Chromebook Power Consumption Comparison
      Display Off Idle Kraken (Avg) Kraken (Peak)
      Samsung Chromebook 500 (Atom N570) 8.82W 11.4W 12.4W
      Samsung Chromebook 303 (Exynos 5 Dual) 4.07W 8.32W 9.27W

      On chromebook XE303,Kraken-Idle=power of (Cpu+memory)=4.2w, I estimate 8X256M DDR3L consumes 2w during kraken test, so cpu consumption is around 2.4w@kraken test. And kraken test couldn't utilities 2 core of exynos5250 completely, so let's double the power of exynos5250, that is 5w.

      BTW, under load memory consumption: DDR3(1.5v)>DDR3L(1.35v)=DDR3L-RS>DDR4>LPDDR2/3.

      When idle, DDR3L-RS < DDR3L.
      I think doubling the power consumption due to CPU utilization is too harsh. While Kraken is a single threaded benchmark the Linux kernel (on Chromebook, and elsewhere according to my observations) likes to constantly swap which core things are running on. That's going to make it hard to power down the core, and Exynos 5 doesn't have any asynchronous DVFS so both cores are always clocked at 1.7GHz. You get some power savings from the core going idle but all of the swapping may even affect this. Android is hopefully better about allowing cores to be powered down when you don't need them.

      Then we don't know where the power was being measured, if it was on the battery or at the wall. Either will incur an efficiency hit that'll be larger the higher the load is. On tablets and Chromebook ~7.2V batteries are usually used, because they're more efficient for the displays (which typically use the most power) but less efficient for the SoC. On phones the situation is reversed so ~3.7V batteries are used. In this case you'll see less power consumption from the SoC, but either way it doesn't impact its TDP. That along with more power efficient (LPDDR2/3, PoP) and probably lower clocked memory will help save power on phones, and it's possible that the Exynos 5 in the package on Chromebook is a leakier variant.


      • #43
        "Current limitations though of running Ubuntu 12.04 on the Samsung Chromebook is that the touchpad didn't work at all for me (some users have reported success), sound is broken, and there isn't any hardware graphics acceleration at this time."

        at the time you posted this
        there was already the arm blog you could have used
        Posted byAndrew Wafaa, 6 COMMENTS
        19 November 2012

        14. The touchpad requires an additional configuration file called 50-touchpad.conf placed into /etc/X11/xorg.conf.d/ Using your preferred text editor create the required file
        (I’m using Vim)
        sudo vi etc/X11/xorg.conf.d/50-touchpad.conf
        Add the contents below
        Section "InputClass"
        Identifier "touchpad"
        MatchIsTouchpad "on"
        Option "FingerHigh" "5"
        Option "FingerLow" "5"


        15. To get audio working copy the contents of ...

        oh and you probably also missed the
        ODROID-U: mini-PC with 1.4 GHz quad-core Exynos SoC for $69 re-fresh news too

        you should probably get a few of those cheap Exynos4 Quad A9's and add them to your existing cluster to give it a big boost

        the U2 Prime 1.7GHz Mali-400, 2 GB of memory and x2 Prime 1.7GHz are over clockable to 2gig so worth a try and a front page perhaps

        they should keep you busy until the Exynos 5 quad/Octo core arrives at least...
        Last edited by popper; 12-09-2012, 04:18 PM.