It hasn't been much of a secret in the SoC space that big.LITTLE on the original Exynos 5 Octa (5410) didn't end up working in the most optimal fashion. Instead of using core migration or the Heterogeneous Multi-Processing (HMP) big.LITTLE models, the 5410 instead used cluster migration which meant either all 4 ARM Cortex A15s or 4 ARM Cortex A7s were lit up.

For those not familiar, there are three big.LITTLE models, core switching, in which any of the A7 and A15 cores can be swapped, cluster switching, in which either all A7s or all A15s can be swapped, or HMP, where the kernel is aware of all cores and can schedule threads to any of the cores all at once. This final model is coming to Exynos 5420 by the end of Q4 2013 and will be available to partners shipping product based on its reference platform.

ARM gave us a chance to take a look at the HMP enabled Exynos 5420 reference platform running through a few demos, showing the kernel swapping in and out A7s and A15 cores as system workload changed. I got to see these in person but ARM has also posted them on YouTube in quality better than I could've captured. 


Exynos 5420 also includes the necessary fixes to the cache coherency interface (CCI-400) that enable it to work this time between the A7s, A15s, and Mali T-628, versus 5410 which didn't enable it and thus suffered loss of efficiency. This makes 5420 the first real platform to take a look at the full promise of ARM's big.LITTLE model. 

Source: Samsung

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  • phoenix_rizzen - Monday, September 16, 2013 - link

    A SoC with 4xA7 + 2xA15 would be interesting. Or, the opposite of the Tegra setup: 4xA7 (main cluster) + 1x A15 (for when you actually need the raw speed). :)

    In those situations, yeah, the HMP makes sense. But in a situation where the big and LITTLE sides have the same number of cores, CPU Migration makes more sense (IMO).
  • frenchy_2001 - Wednesday, September 11, 2013 - link

    No, Exynos 5410 had a hardware bug limiting it to cluster migration (CCI-400 problem).
    The Exynos 5420 fixes this problem, however there was no software to take fully advantage of it, so the hardware would manage the migration and the scheduler would only see 4 virtual CPUs (each a pair of CPU, A7+A15).
    Linaro worked on the Linux Kernel scheduler for Heterogeneous Multi-Processing, which allows to show all 8 cores to the scheduler and let it decide what to run where (while caring for power/temp limits). This is a software patch, that will be distributed around the end of the year. There will be no need for newer hardware.
  • ddriver - Wednesday, September 11, 2013 - link

    Hey ANAND admins, how hard would be to block this spam, considering it always begins with "Live my job" and always has the $82h and sitting in front of the new imac - I mean come on, what is the excuse to keep tolerating this? Like it is not bad enough there is no edit button... come on, what are you people being paid for?
  • jljaynes - Wednesday, September 11, 2013 - link

    If Anandtech pays me $82/hr I will sit at my computer and delete spam for them.
  • wintermute000 - Thursday, September 12, 2013 - link

    I'll do it for $80/hr
  • retrospooty - Wednesday, September 11, 2013 - link

    "Hey ANAND admins, how hard would be to block this spam"

    They would probably have to put in one of those irritating pictured phrases with jumbled letters to confirm you are human. The cure is worse than the disease LOL.
  • Roland00Address - Wednesday, September 11, 2013 - link

    Can we get a button to report said post to the moderator like we have for the forums?
  • JarredWalton - Wednesday, September 11, 2013 - link

    Generally speaking, any of us editors (Brian, me, Anand, Ryan, etc.) can mark something as spam and delete it, and we do it as soon as we see it. Of course, posting a reply to said spam ends up with your posts getting pushed to the bottom of the comment chain as a response to nothing. Considering this article has only been live for less than 12 hours and the spam is gone, I'd say we're doing okay. Just ignore the spammers and we'll take care of them within a few hours, or if you must you can email and tell them which article has a spam comment.

    And as a final note, if we mark a comment as spam, it will delete all comments everywhere by that user, so if you value your account and comments please don't spam.
  • tuxRoller - Wednesday, September 11, 2013 - link

    Just to be clear, this is not a "Samsung Innovation" but a project that has been coordinated, and fulfilled by Linaro, and others.
    I don't expect Samsung to play this any other way than "Look what WE'VE done!" but it'd be nice if it wasn't portrayed as something Samsung did since all you need to support the work is to have a compliant big.LITTLE system and run the new linux scheduler.
  • everex11 - Monday, September 16, 2013 - link

    like Diane replied I am alarmed that a mother able to profit $5803 in 1 month on the computer. my

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