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
Chrome - AnandTech Frontpage
Off the bat we see quite a large difference in the power state distribution graphs. Chrome seems to place much higher load on the little cores compared to S-Browser. When looking at the run-queue chart we see that indeed all cores are almost at their full capacity for a large amount of time.
What stands out though is a very large peak around the 4s mark. Here we see the little cores peak up to almost 7 threads, which is quite unexpected. This burst seems to overload the little cluster's capacity. The frequency also peaks to 1.3GHz at this point. The reason we don't see it go higher is probably that the threads are still big enough that they're picked up by the scheduler and migrated over to the big cluster at that point.
The big cores also see a fair amount of load. Similarly to the S-Browser we have 1 very large thread that puts a consistent load on 1 CPU. But curiously enough we also see some significant activity on up to 2 other big cores. Again, in terms of burst loads we see up to 3 big CPUs being used concurrently.
The total run-queue depths for the system looks very different for Chrome. We see a consistent use of 4-5 cores and a large burst of up to 8 threads. This is a very surprisng finding and impact on the way we perceive the core count usage of Chrome.
Facebook
Twitter
RSS
157 Comments
View All Comments
lilmoe - Tuesday, September 1, 2015 - link
"if the interest is high enough":/ Really?
zaza - Saturday, September 5, 2015 - link
Yes Please. It would be nice to see if the same or similar tests works on snaprdagon 810,801 and 615 and Mediatek chips, and intel SoCerchni - Thursday, September 17, 2015 - link
A follow-up with synthetic would be quite interesting.aryonoco - Saturday, September 5, 2015 - link
I just wanted to reiterate the point here an thank the author for this great piece of technical investigative journalism.Andrei, thank you for this work. It is hugely invaluable and insightful.
tipoo - Tuesday, September 1, 2015 - link
Very interesting article. Seems like the mantra of "more cores on mobile are just marketing" was wrong in terms of Android, seems to dip into both four core big and little clusters pretty well. That puts the single thread performance having lagged behind the Apple A series (up until the S6 at least) in a new light, since it can in fact use the full multicore performance.tipoo - Tuesday, September 1, 2015 - link
*That is, barring gaming. More core Android functions do well with multithreading though.jjj - Tuesday, September 1, 2015 - link
In gaming there is a big advantage. By using mostly the small cores you allow for more TDP to go to the GPU. One more relevant thing would console ports in the next couple of years when mobile GPUs will catch up with consoles. The current consoles have 8 small cores and that fits just right with many small cores in Android.retrospooty - Tuesday, September 1, 2015 - link
Not really sure whos "mantra" that was. People that don't understand what the big.little architecture is like some angry Apple fans?tipoo - Tuesday, September 1, 2015 - link
Well sure, whoever they were, but it was a pretty common refrain for every 8 core SoC.soccerballtux - Tuesday, September 1, 2015 - link
for one, it was my mantra. I liked having 4 cores because 2 wasn't enough, but according to my hotplugging times, I only really need 3 for optimal experience most of the time