Posted by Martin R. 2 years ago

Samsung’s Octa-Core not as energy efficient as we thought??


exynos-5-octa-jpg

So we all know that Samsung’s Octa is their big technical achievement this year at least that is what they like us to think.

The well-known and respected Kernel Dev AndreiLux discovered that the octa isn’t fully energy-efficient optimized. And he said Samsung has chosen the most awful implementation of the Octa-Core possible.

The Octa was advertised as followed:

A better picture can been seen below:BigLittle

This is a unofficial leaked presentation from their semiconductor business. Here you clearly can see how the cores should be working.

So what did AndreiLux find out, well he found out that the cores only can work in clusters so only 4 A7′s or 4 A15′s at the time.
I contacted him on XDA and asked him for some clarity, I will quote some of his message.

“Basically there are three modes of operation of big.LITTLE:

Cluster migration: When load rises, just like when a phone increases is frequency per DVFS, all the cores will jump from the LITTLE processor to the big one. You either have 4 A7 cores or 4 A15 cores online.

Core migration: When load rises, it will only jump those cores from the LITTLE processor whose load exceeds the capacity of the A7 cores: You can have a single A15 online with 3 A7′s on. Or any other combination of a total of 4 processors.

HMP (Heterogeneous Multi-Processing): This is a vastly more complex working mechanism, and its implementation is also an order of magnitude more sophisticated. It requires the kernel scheduler to actually be aware of the differentiation of between the A7 and A15 cores. Currently, the Linux kernel is not capable of doing this and treats all CPUs as equals. This is a problem since we do not want to use the A15 cores when a task can simply me processed on an A7 core with a much lower power cost.”

It seems driver related and it is way to difficult to comprehend for us normal folks, so I will not go into the technical details. If you are still interested in the technical details please follow this link.

So is this thing not finished yet, is it a hardware limitation or is it something else, well only Samsung knows and lets hope they will come with an answer. But as always do not count on it, cause Samsung hasn’t got a good reputation if it comes to the developer community.

I will stop with a quote from him which seems right at his place here.

“Matter of fact is: The CPU isn’t running under optimal power efficiency right now, you cannot argue with that.”

Thank you AndreiLux!

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13 comments on “Samsung’s Octa-Core not as energy efficient as we thought??

  1. Jaime Larios 2 years ago said:

    I thought we all knew this is how the Exynos 5 Octa worked… all A7 or all A15. I know this is not efficient, but thats the way they have been saying it works.

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  2. zapatavini 2 years ago said:

    i think samsung has limited the exynos 5 processing power and energy efficense in order to reduce the gap with the snapdrragon 600 version,. I think we will see the real power of the exynos 5 odta in the galaxy note 3 which will be an unified versin with only the exynos as it’s porccesor.

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  3. gtone339 2 years ago said:

    Just needs more fine-tuning and we shall see it’s true potential. A patch or 2 can remedy it and it always happens whenever there’s a new Soc on a new mobile device!

    Don’t worry folks, this Octa-core Soc will be truly reliable and efficient!

    Report this comment

  4. maxximuscool 2 years ago said:

    It is not the chip’s fault. It is more complex than this. The chip is capable of switching dynamically but the problem is the software and drivers on Android is not fully taking the advantage of the BigLittle technology just yet. If Google updating the kernel to support such dynamic profile then we’ll see these work better and does what it is supposed to do. I’m sure it is probably the most challenging thing to do right now by Samsung to get this new technology to work properly with the limitation of Android Kernel.

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  5. 3c71 2 years ago said:

    From the presentation I see model 3 as both clusters active with a ‘modified kernel scheduler’. So IMO it says it can load threads on every cores, probably based on threads activity and core’s raw power.

    Whether it’s already implemented or not is just a software problem, which will eventually get fixed. But when I see a S4 quad-core benchmark topping at 27000 and the same benchmark on the S4 octa-core topping at 30000 I’d say it’s not taking advantage of all 8 cores very well, is it?

    However nothing proves the benchmark app is ready for 8 cores either?

    That said, can’t wait to get this device as I develop an app to manage CPU.

    Nevertheless I wonder about the article’s title: was expecting battery benchmarks/tests, so maybe it should be titled “not as performant efficient” or “not as fast” instead of energy.

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  6. adrianzka 2 years ago said:

    Why not samsung add a software update to give a setting that will make users able to choose which big.LITTLE they choose ?

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  7. snowQA 2 years ago said:

    “Samsung’s Octa-Core not as energy efficient as we thought??”
    ACCORDING TO WHOSE THOUGHT? The article is misleading as it paints Samsung like a lier.

    Yes the Octa core is more efficient than your ordinary processor because of the high efficient A7s. It is also a HIGH performance Processor because of the A15s. This is so because priority is given to the power efficient A7s. The A15s are only switched to when HIGHER performance is required.

    But even the A15s have been made to be more power efficient than other similar processors other than the A7s when performing similar tasks.

    This makes the Octa-Core the most energy efficient and the most powerful Or simply the best Processor for mobile devises at the moment.
    But when the HMP (Heterogeneous Multi-Processing) is implemented with the use of Linux 3.8 kernel this CPU will get even better.

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    • Nicko80 2 years ago said:

      Like the DEV from XDA says.. its a driver problem… they will work on it absolutly and that is why most countries received the quadracore version..

      Now ..the cores only work in a 4 formation , that will consume more, but imagine the consumption of memory of a driver to control the 8 cores, I think thats the problem , a 2 GB memory phone with all the amount of firmware and bloatware they induce in it , it will not be enough… and it will heat up that phone for sure…. and that is a real problem … you will never see this phone workink with 8 cores at same time, as it was anounced on january in las vegas, it will burn out…unless you instal a van on the back….

      Just remember…this is a smartphone..not a computer…

      Report this comment

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