Curious about the 8 Core vs 4 Core

[Charles Lambton]

I mentioned it in another benchmark thread but if anyone knows a definitive answer or at least has a theory about it I'd love to hear it.

Why have two sets of four core processors differently clocked for power savings as in the Galaxy S4, when you can just lower the clock and power required on just one quad core, the same way it's been done for quite a while. Would there be a major difference in power saved ? A large enough difference to justify the cost difference for the manufacturer?


It almost seems to me like they are trying to go the Tegra 3 route of 4 x high powered core's and 1 x low powered cores but completely missing the point of it.

 

[Jerry Hildenbrand]

The "big" side of the 8-core big.LITTLE Exynos is a Cortex A15, out-of-order, triple issue processor with a pipeline length of between 15 and 24 stages.
The "LITTLE" side is a Cortex A7, in-order, non-symmetric dual-issue processor with a pipeline length of between 8 and 10 stages.

The LITTLE side uses a lot (a lot is relative -- we're still talking milliwatts and microvolts) less power to process information than the big side would even at a lower clock speed, primarily because of the "shorter" pipeline. Remember, every little thing helps in a mobile phone. This is far less important in your multi-core desktop.

Both sides can each perform the exact same calculations and functions, but when things start to back up clock cycles, the big side kicks in and takes over.

The questions I have:
How robust is Samsung's engineering for when the big side kicks in? (I think very, Samsung knows microproccessers VERY well)
How many ?s will it take to switch? That is a potential lag point.
When will Samsung get a "super" tablet version of this chip with a quad-core A15 "big" side clocked at 2.2 GHz?

 

[Charles Lambton]

The "big" side of the 8-core big.LITTLE Exynos is a Cortex A15, out-of-order, triple issue processor with a pipeline length of between 15 and 24 stages.
The "LITTLE" side is a Cortex A7, in-order, non-symmetric dual-issue processor with a pipeline length of between 8 and 10 stages.

The LITTLE side uses a lot (a lot is relative -- we're still talking milliwatts and microvolts) less power to process information than the big side would even at a lower clock speed, primarily because of the "shorter" pipeline. Remember, every little thing helps in a mobile phone. This is far less important in your multi-core desktop.

Both sides can each perform the exact same calculations and functions, but when things start to back up clock cycles, the big side kicks in and takes over.

The questions I have:
How robust is Samsung's engineering for when the big side kicks in? (I think very, Samsung knows microproccessers VERY well)
How many ?s will it take to switch? That is a potential lag point.
When will Samsung get a "super" tablet version of this chip with a quad-core A15 "big" side clocked at 2.2 GHz?

Thanks for the great info, I can't wait to see what real world differences the big/little architecture will bring to battery life. I'm going HTC either way but I want to see if it actually makes a noticeable difference in battery life or if it's more of a marketing gimmick on Samsung's part to say they have the first 8 core phone.