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 - BBC Frontpage
The little core data doesn't look much different than what we saw on the AnandTech frontpage. The little cores see a consistent high load, with a fairly large peak towards the main rendering phase of the page.
Chrome again seems to cause the system to spawn more threads than what the little cluster can accomodate.
The big cores also behave similarly to what we saw on the AnandTech front-page. There's a consistant load of a single large thread with some bursts where up to all 4 CPUs are doing some processing.
The total run-queue depths for the system again confirm what we saw in the previous scenario: Chrome is able to consistently make use of a large amount of threads, so that we see use of up to 6 CPUs with small bursts of up to almost 9 threads.
What is interesting about the Chrome results is that most of the threads are placed on the little cores, meaning we have a large amount of small threads. Because the migration mechanisms of HMP don't migrate threads below a certain performance threshold, this causes some oversaturation of the little CPU cluster.
This is an interesting implication for non-heterogeneous 8 core designs such as seen from MediaTek. In such a scenario having 8 little cores at more or less the same performance capacity would indeed make quite some sense. It's again MediaTek's X20 design with 2 clusters of 4 cores and a cluster of 2 high performance cores which comes to mind when looking at these results, as I can't help but think that this would be a use-case which would make perfect sense for that SoC.
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Gigaplex - Thursday, September 3, 2015 - link
An interesting and thorough analysis, although I'm concerned at some of the assumptions made in some of the conclusions. Just because a queue of 4 threads makes all the 8 big.LITTLE cores active doesn't mean that the architecture is effective. For all we know, the threads are thrashing back and forth, draining precious performance per watt.darkich - Friday, September 4, 2015 - link
Andrei, your articles are in a league of their own. Thanks for the great workmelgross - Thursday, September 10, 2015 - link
I'm still not convinced. The fact that it's doing what it does on these chips doesn't mean that their performance is as good as it could be, or that power efficiency is as good. We really need to see two to four core designs, with cores that are really more powerful, to make a proper comparison. We don't have that with the chips tested.blackcrayon - Thursday, October 8, 2015 - link
Exactly. It should at least show a design with a small number of powerful cores. Obviously with Apple's A series chips you have the issue of dealing with a different operating system underneath, but can't they use a Tegra K1 or something?Hydrargyrum - Friday, September 25, 2015 - link
The stacked frequency distribution graphs would be a *lot* easier to read if you used a consistent range of different saturations/intensities of a single colour (e.g. go from bright=fast to dark=slow), or a single pass from red to blue through the ROYGBIV colour spectrum (e.g. red=fast, blue=slow), to represent the range of frequencies.By going around the colour wheel multiple times in the colour coding it's *really* hard to tell whether a given area of the graph is high or low frequency. The difference in colour between 1400/800, 1296/700, and 1200/600 are very subtle to say the least.
Ethos Evoss - Thursday, November 12, 2015 - link
anandtech always uses weird non-popular words on its own site type ''heterogeneous '' never heard in my life and even usa or uk ppl have to search in cambridge/oxford dictionary :DDDImmediately u can say it is DEFO NOT USA or UK website.. They do not use such difficult words AT ALL :)
Ethos Evoss - Thursday, November 12, 2015 - link
ANd mainly they use when it comes to china products .. like mediatek or kirin or big.little topic etc..This site is DEVOURED or we could say powered by apple.inc :)