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Date: Mon, 22 Dec 2014 23:36:19 +0300
From: Solar Designer <>
Subject: Re: ARM exynos 5410 benchmark results

On Mon, Dec 22, 2014 at 07:12:22PM +0100, wrote:
>   Actual hard TDP numbers are hard to find for this SoC, but reading
> enough marketing material would suggest 3-4 W TDP.
>   There is a slide from a ieee conference at 
> that would suggest something between 4 and 6 W TDP.
>   Keep in mind that this is the first big.LITTLE SoC. It'll be interesting
> to see what the 5430 (20nm), and 74xx (20nm) will do.
>   The system (Odroid-XU) is delivered with a 5V 4A power supply, and

Thanks for the info.

> supposedly a 5V 2A supply will not work. This is something I have not
> tested.

You'd need to measure the current before you test this, or you'd likely
burn the 2A PSU.

> > I think you wrongly stated that you ran 8 threads.  I think you
> > only ran 4.  If so, please correct that little detail.
>   Checked, and I did fill it out correctly. Total cores is 8 for this
> SoC, it's big.LITTLE. 4 x Cortex-a7 which can switch to 4 x Cortex-A15.
>   So total cores turns out to be 8, with only 4 being active at 
> any one time.

Oh, I didn't realize you specified "4 / 8" rather than "8 / 4" (like we
would for a more typical system with multiple logical CPUs per core).
That's not how this notation was meant to be used, but it's a curious
extension we could consider for cases such as yours.  I think it'd get
very confusing and ambiguous when those CPUs also start supporting
multiple threads per core, though.  For example, what if your chip
supported 2 threads/core?  Would you specify "8 / 8", because you'd run
8 threads on 4 cores, and have another 4 cores idle (which would in fact
be the optimal way to use that chip)?  But people would surely read this
as 8 threads running on 8 cores!  So let's not go for those extensions.
I'll fix your entry to "4 / 4" now, because for our purposes the chip
has 4 cores.


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