A modern phone CPU is way closer to a modern desktop CPU than what most people think, due to the mobile-first (and power-efficiency-first) nature of most of the current CPUs in the market - in the detriment of pure performance.
Power-efficiency matters more than pure single-threaded performance in both the mobile and server markets.
Desktop processors generally have much higher single threaded performance. Thus apps can more often afford to take a performance hit on desktop than on mobile.
And phone CPUs can be more complex than most desktops, afaik big.LITTLE is fairly common (multi core, with different performance / power tradeoffs between the cores).
A major difference is in sustained performance, not peak performance. Mobile CPUs often have cores these days that are comparable to desktop/server CPU cores but they lack the cooling to sustain peak performance for very long. They're thermally throttled very rapidly.
That being said you could take such a CPU and given it desktop-like power and cooling and it could perform like a desktop chip.
That claim would be highly suspect in general, given that a desktop CPU has at least 10 times more headroom in power consumption.
For such a claim to be true, you would have to expect that the phone CPU is somehow 10 times more efficient per Watt, while having the same kind of architecture (general CPU, not GPU/TPU/...).
I don't mind the downvotes, but more interested to know why if anyone cares to comment? I should have specified that by desktop/mobile, I do mean desktop/laptop essentially (and, not smartphone CPUs). And, I am talking about Intel/AMD largely, and how I perceive their evolution over the past two and half decades.
In short, I think "optimizing for games" means nothing to a CPU designer at say Intel, and anyways qualitative differences (expanding the ISA, or integrating new features on the IC) are more expensive to develop and sometimes tricky to market. Instead, marketing quantitative differences is much easier (hence optimize for benchmarks) - though arguably no easier to develop. Witness Intel's first rocky attempt at targeting the benchmarks in the early 2000s: Netburst [0]. Of course, in the past 5 years, things have changed (the rise of smartphones, meteoric rise in GPU performance with expanding markets & new software, CPU "per core" performance stagnation), so Intel is in the process of re-positioning itself.
It delivers very high single-core performance compared to smartphone processors, which was the subject under discussion. How it stacks up against other desktop/server processors is important within that market, but a distinguishing feature of desktop and server processors is that they all have high single-core performance.
Because faster CPU on phones mostly doesn't matter.
I have a midrange Android phone that I use to watch videos, listen to music and podcasts, internet browsing, chat, banking. The only thing I don't do on my phone is play games. I never once caught myself thinking "boy, this phone is slow, a faster CPU would do wonders here". It doesn't ever even feel hot to the touch.
I bet it can run just fine most mobile games available. What the hell are people running on their phones that need a better CPU?
Unfortunately, mobile processors seem to still be undergoing the same rapid increase in power that desktop systems used to, and the OSes and applications are being built for top-of-the-line phones. Even my iPhone 6 struggles with modern versions of iOS, despite being under 4 years old.
The thing is, that CPU bit is not really relevant for the average consumer, anymore. Flagship phone CPUs have been good enough for web browsing and casual app use for about 2 years.
Not that I'm against extra horse power, we'll find a use for it. But we're in "desktop land", almost, for smartphone CPUs. They're good enough.
The real smartphone battles now are in camera quality, gaming oomph and battery usage.
Energy efficiency doesn't necessarily comes from being better on full load. Smartphonechips provide tons of power saving mechanisms, true but also are quite limited on how they operate.
I assume that generic code on a x86 desktop cpu should be more efficient by watt/work in comparison on a mobile chip. I'm also not sure how a smartphone is rated for 100% cpu load 24/7
A phone, while powerful, is still nowhere near a modern PC in terms of performance. As you push for more and more performance, you’ll pay increasingly more, both in power and money, for increasingly smaller gains.
There are all sorts of things that a new phone can do that one from a few years ago, even if you don't personally use it. Similarly even if you don't play games, plenty of other people do.
It's also incorrect to only consider phones, as TSMC manufactures many (most?) of the non-x86 laptop/desktop CPUs, where performance is much more overtly desired.
The final point is that this isn't just a matter of smaller equals faster, but also smaller equals less power - which I assume does matter to phone users.
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