Why don't we see more than 8 cores in phones

[Wolly9102]

Hello forum,

 

I was thinking about the other day. We had 8 cores in phones for a couple of years now. And I know there are a few phone's with more than 8 cores. But it doesn't seem that it's expanding like the pc and laptop market are doing.  But phones get bigger in RAM and storage but no extra cpu cores. Is there a specifc reason for this? Would like to know

[Electronics Wizardy]

most smartphone chips are big.LITTLE so there are faster cores, and slower cores, so its not really equal to 8 full cores.

 

ALso a lot of tasks just don't scale well to lots of cores still, so there isn't really a point in adding those cores.

[DrMacintosh]

ARM is a much newer and much more efficient architecture. Simply but, phones aren't adding oodles of cores because it would server no purpose. The A13 Bionic is the most powerful SoC available in a phone and it's only a 6 Core design with 4 of those being low power cores for doing regular tasks with the last 2 only firing up if you're playing a game or encoding a video. 

[porina]

Turn the question around a bit, what would you do if a phone had more cores that you can't do now, or at least not as well?

 

This is in part complicated by the different cores as already mentioned, but also there can be dedicated chips which you could also call a fixed function core to help with specific tasks.

 

It isn't like in desktops (or laptops) where generally speaking, if you have a multi-thread scaling workload, within a given power budget you can do work more efficiently with more than fewer cores. Up to some point anyway, scaling problems will set in at some point and start to work against you. 

[Applefreak]

The number of cores will depend on the workload you have. Most applications will not utilize more than 2 cores, some have support for more than that but it rarely makes any sense. Also one must differentiate between full ARM cores and mobile cut down ones. Even though Apple's new ARM design is sort of superior in phones, in heavy multi-threaded non phone workloads it is not that great. Modern phone cpus are highly specialized and will work on many different things simultaneously, thus making things snappier for the end user. For example updating websites in the background while other cores are gaming and others are keeping your notifications up to date and others keep handle all the network traffic. I am fairly certain future phones will have more cores if 5G and 4k 240 hz screens will become mainstream in phones. Full ARM core devices already have more than 8 cores and also at much higher clock speeds. I believe the main limitation of cores is power consumption, meaning the inefficiency or limited capacity of lithium batteries without increasing the size of those phones in the end. The reason behind bezel-less devices is not more screen but more space for the battery. Increasing a screen is cheap, building a better battery is much more difficult (see Note 7). 

[Zodiark1593]

5 hours ago, Wolly9102 said:

Hello forum,

 

I was thinking about the other day. We had 8 cores in phones for a couple of years now. And I know there are a few phone's with more than 8 cores. But it doesn't seem that it's expanding like the pc and laptop market are doing.  But phones get bigger in RAM and storage but no extra cpu cores. Is there a specifc reason for this? Would like to know

Performance gains are being made in per core performance. All else being equal, more performant cores tend to be larger and more power hungry. Adding additional cores will further strain the power budget at the cost of single thread performance (relatively important for mobile workloads), in addition to expanding die size that could be used for other things (like GPU), and complexity of interconnects to connect the cores to the caches and memory interface. 
 

While Cortex A53s and A55s are especially small and inexpensive to add, they actually aren’t particularly efficient (performance/watt) nowadays. 

 

That said, there are a few mobile Deca-core SoCs out there. 

[Wolly9102]

Thanks everybody for answering  .

[Roswell]

On 5/18/2020 at 6:20 PM, DrMacintosh said:

ARM is a much newer and much more efficient architecture.

ARM isn't new, it's been around for 35 years. x86 only predates it by 6 years I believe.