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
Play Store App Updates
The Play Store update process seems to be extremely liberal with spawning threads. The little cores are severely over-capacity as we see package updates loading up to 8-9 threads onto the cluster. The two major peaks towards the end of the log especially demonstrate this fact as all CPUs vastly exceed the optimal run-queue depth of 1 when under load, which causes the scheduler to need to preemt between multiple processes.
While it may have been intriguing to see the little cores loaded to such extent, the big cluster seems outright shocking as it as well sees very significant thread-placement. This is one of the rare scenarios where having 4 big cores is not enough. Similarly to the little cores, we see peaks where the run-queue depth vastly exceeds the optimal value of 1.
When looking at the total system run-queue depth, things look for a lack of better description, quite ridiculous. We routinely have peaks where all 8 cores of the system are fully loaded and peak at over 10 threads. It looks like Google is able to massively parallelize the app update process and take advantage of even the highest core-count SoCs. This scenario is absolutely about maximum throughput and performance while utilizing all available hardware resources.
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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 :)