Qualcomm SoC & ARMv8 custom core discussions

Discussion in 'Mobile Devices and SoCs' started by Nebuchadnezzar, Jan 20, 2015.

  1. Mariner

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    Interesting to see that the new flagship LG G4 contains the Snapdragon 808 and not the faster 810.

    I have to admit that the heat problems we've seen reported have put me off phones containing the 810 but the question is whether the downgrade to the 808 (and presumed reduce of heat problems) will allow the G4 to compete with flagship devices in the minds of the consumer. Personally, I think the 2 core A57 + 4 core A53 setup might be a reasonable choice, but the lower GPU performance could certainly be seen as a disadvantage with a QHD screen.

    Looks like an interesting device with the camera and screen looking particularly good - just a pity it is so bloody big!
     
  2. Laurent06

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    Are Silvermont clusters clocks independent? I have seen no study of how clocks/turbo behave on it.
     
  3. Rys

    Rys Graphics @ AMD
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    Clock and voltage are independent for Silvermont, unless I'm mistaken.
     
  4. ToTTenTranz

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    I think what should hurt more in that resolution is the downgrade in memory bandwidth, as LG apparently decided to stick with LPDDR3, and the 808 uses two 32bit channels, whereas the 805 uses two 64bit.
    Then again, my HTC One uses 533MHz LPDDR2 for 1080p and for normal (no 3D games) usage it handles everything just fine.
     
  5. Laurent06

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    On a core basis (which would mean L2 cache is behind a synchronizer) or on a pair of cores basis?
     
  6. Rys

    Rys Graphics @ AMD
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    On a pair/module basis, sorry I wasn't clear!
     
  7. Laurent06

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    It makes sense, thanks :)
     
  8. Exophase

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    Quad core Silvermont SoCs have a single CPU core voltage domain. AFAIK clock domains are separate, although I haven't yet been able to determine this from the datasheet.
     
  9. mczak

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    Sure about that? Realworldtech claims voltage rails are per module (and core clock could vary per core actually, and not per module, though using the same base clock, at least in theory). http://www.realworldtech.com/silvermont/8/
     
  10. Nebuchadnezzar

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    So now we basically know everything about the S820 except its actual performance / Kryo's IPC.
     
  11. Exophase

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    It says a module has a common voltage rail, but it doesn't say that SoCs consisting of multiple modules will have separate rails. Maybe Intel could have made such a thing, but the ones they made have a single core power domain. If there were more they'd have to be visible on the datasheet as it relies on external VRMs.

    So basically we still know almost nothing ;) That, and things like cache sizes, although I guess you could call those mere details of performance.
     
  12. Rurouni

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  13. Rys

    Rys Graphics @ AMD
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  14. Alexko

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    What does "location" mean?

    Edit: actually, the labels seem to be completely wrong. The CPU part in particular should be much bigger since a block of 4 identical structures is clearly identifiable in the CPU + memory subsystem + Adreno VPU part.
     
  15. Nebuchadnezzar

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  16. Rys

    Rys Graphics @ AMD
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    Looks legit to me. Pretty sure all modern SoC designs today have fully utilised, completely rectilinear major blocks you can identify like that. Qualcomm are the masters at it, actually.
     
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  17. Nebuchadnezzar

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    The sarcasm hurts :D But yea it looks like the actual die is some SoC with Krait as I remember the CPU block looking like that.
     
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  18. Rys

    Rys Graphics @ AMD
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    Yeah, it's MSM8974 (S800). Quad Krait 400 + A330.
     
  19. Voxilla

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    Just got myself a S6, not bad, volumark score of 122.
    Wondering how that compares to the 820.
     
  20. Raqia

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