The Mobile CPU Core-Count Debate: Analyzing The Real World
by Andrei Frumusanu on September 1, 2015 8:00 AM EST- Posted in
- Smartphones
- CPUs
- Mobile
- SoCs
S-Browser - AnandTech Frontpage
Again staying with the S-Browser, we check the behaviour of just pure web-page rendering. This time we load the AnandTech front-page without scrolling through the page. The page is slightly heavier as we have more graphical elements as opposed to text on the previous article page.
This time around, we a more even distribution of the load on the little cores. Again, most of the 4 CPU cores are active and have threads placed onto them, averaging about 2.5 fully loaded cores.
The frequency distribution is much more variable in this scenario, as the cluster makes wide usage of the frequency range available to itself. On the power state distribution chart we see that most CPUs are still able to enter their power-gating states, indicating that we're mostly handling very short bursty loads.
The biges cores seems much less loaded in this scenario, as most of the time except for a small peak we only have 1 large thread loading the cluster. Because of this, we expect the other cores to be shut down and if we look at the power state distribution we guessed correctly.
The total amount of threads on the system doesn't change much compared to the previous scenario: The S-Browser still manages to actively make good use of up to 4 cores with the occasional burst of up to 5 threads.
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Hrobertgar - Tuesday, September 1, 2015 - link
Your spikes on the video recording appear to be every ~4 secs of video, could the CPU spikes be app / memory related?badchris - Tuesday, September 1, 2015 - link
Thank you for this excited article.And one problem,how do we explain 2 big core Snapdragon 808 is more efficient than 4 big core Snapdragon 810?Andrei Frumusanu - Tuesday, September 1, 2015 - link
You cannot make comparisons between different SoCs even if they have the same CPU IP and the same manufacturing process. The S808 is different from the S810 which are again different from Nvidia's X1 even if all 3 have A57 cores on TSMC 20nm.badchris - Tuesday, September 1, 2015 - link
nvm,i should realize this comparison is not scientific.metafor - Tuesday, September 1, 2015 - link
The S808 and S810 should be fairly similar though. That's not to say you can say that the only difference is the CPU configuration but a similar study on what the behavior is like on a different SoC with fewer cores would be helpful.Threading isn't 100% free and neither is thread migration. It might be good to take a look at just what the S810 is doing over time compared to the S808 in terms of CPU activity.
Andrei Frumusanu - Tuesday, September 1, 2015 - link
I have data on all of that... It's just in need of being published in an orderly fashion.kpkp - Tuesday, September 1, 2015 - link
There are quite few other differences beside the 2 cores, starting with the memory controller.badchris - Tuesday, September 1, 2015 - link
thx for your notice.there're something i forgotnpp - Tuesday, September 1, 2015 - link
As an ex-Android developer I can remember that the SDK not only encourages, but sometimes straight out enforces extensive usage of threads. For example, around API level 14/15, making a network request in the main thread would throw an exception, which may seem obvious to experienced developers but wasn't enforced in earlier versions. This is a simple example, but having the API itself pushing towards multi-threaded coding has a positive effect on the way Android developers build their apps. I'm not sure then why Google's own browser would be surprising for its usage of high thread counts - even a very basic app would be very likely to spawn much more than 4 threads nowadays.Arbie - Tuesday, September 1, 2015 - link
"I was weary of creating this table..."That's not surprising, after all your work ;-).
Terrific article BTW which is up to Anandtech's long-time standards. Seems like a mini master's thesis.