S-Browser - AnandTech Article

We start off with some browser-based scenarios such as website loading and scrolling. Since our device is a Samsung one, this is a good opportunity to verify the differences between the stock browser and Chrome as we've in the past identified large performance discrepancies between the two applications.

To also give the readers an idea of the actions logged, I've also recorded recreations of the actions during logging. These are not the actual events represented in the data as I didn't want the recording to affect the CPU behaviour.

We start off by loading an article on AnandTech and quickly scrolling through it. It's mostly at the beginning of the events that we're seeing high computational load as the website is being loaded and rendered.

Starting off at a look of the little cluster behaviour:

The time period of the data is 11.3s, as represented in the x-axis of the power state distribution chart. During the rendering of the page there doesn't seem to be any particular high load on the little cores in terms of threads, as we only see about 1 little thread use up around 20% of the CPU's capacity. Still this causes the cluster to remain at around the 1000MHz mark and causes the little cores to mostly stay in their active power state. 

Once the website is loaded around the 6s mark, threads begin to migrate back to the little cores. Here we actually see them being used quite extensively as we see peaks of 70-80% usage. We actually have bursts where may seem like the total concurrent threads on the little cluster exceeds 4, but still nothing too dramatically overloaded.

Moving on to the big cluster:

On the big cluster, we see an inversion of the run-queue graph. Where the little cores didn't have many threads placed on them, we see large activity on the big cluster. The initial web site rendering is clearly done by the big cluster, and it looks like all 4 cores have working threads on them. Once the rendering is done and we're just scrolling through the page, the load on the big cluster is mostly limited to 1 large thread. 

What is interesting to see here is that even though it's mostly just 1 large thread that requires performance on the big cores, most of the other cores still have some sort of activity on them which causes them to not be able to fall back into their power-collapse state. As a result, we see them stay within the low-residency clock-gated state.

On the frequency side, the big cores scale up to 1300-1500 MHz while rendering the initial site and 1000-1200 while scrolling around the loaded page.

When looking at the total amount of threads on the system, we can see that the S-Browser makes good use of at least 4 CPU cores with some peaks of up to 5 threads. All in all, this is a scenario which doesn't necessarily makes use of 8 cores per-se, however the 4+4 setup of big.LITTLE SoCs does seem to be fully utilized for power management as the computational load shifts between the clusters depending on the needed performance.

Introduction & Methodology Browser: S-Browser - AnandTech Frontpage
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  • lilmoe - Tuesday, September 1, 2015 - link

    "if the interest is high enough"

    :/ Really?
    Reply
  • 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 SoC Reply
  • erchni - Thursday, September 17, 2015 - link

    A follow-up with synthetic would be quite interesting. Reply
  • 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.
    Reply
  • 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. Reply
  • tipoo - Tuesday, September 1, 2015 - link

    *That is, barring gaming. More core Android functions do well with multithreading though. Reply
  • 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. Reply
  • 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? Reply
  • tipoo - Tuesday, September 1, 2015 - link

    Well sure, whoever they were, but it was a pretty common refrain for every 8 core SoC. Reply
  • 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 Reply

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