Linus Torvalds: Too many cores = too much BS

[Ramses]

I for one am going to be overly disappointed if in a decade we are still using the same "cpu" and silicone and cores and such. As another poster mentioned in I think this thread, these aren't the things that are going to let us travel to the stars or do dramatically other/different than we've been doing. Wouldn't be the first time I was disappointed but a guy can hope.

 

[frozentundra123456]

Today is 2015 and the mainstream is 4 cores, you don't think that in 5 years time we would have 16 cores?

And in 10 years time there are enough innovations in the pipeline that even if half made it through we are going to see huge numbers of cores. Doesn't mean its going to be the same type cores as today.

I would argue if you look at the total X86 cpu market, including enterprise and general usage the "mainstream" today is actually still 2 cores, especially including laptops. I work at a large university, and nearly every lab and office has several computers, but I dont know a single one that is a quad core. They all run mainly office and light statistical/data base programs, so there is no need for more than a dual core. Same is true for my friends and family. All they do on their computers is surf the net and do social networking. No need for more than a dual core here either.

And no I dont think there will be more than 4 cores mainstream, much less 16 in 5 years. And those four core devices could well be wimpy ones like atom/kabini.

 

[NTMBK]

I would argue if you look at the total X86 cpu market, including enterprise and general usage the "mainstream" today is actually still 2 cores, especially including laptops. I work at a large university, and nearly every lab and office has several computers, but I dont know a single one that is a quad core. They all run mainly office and light statistical/data base programs, so there is no need for more than a dual core. Same is true for my friends and family. All they do on their computers is surf the net and do social networking. No need for more than a dual core here either.

And yet the majority of phones these days (Apple excluded) are 4 cores or more- even low end phones have quad A7 clusters. And phones are arguably most peoples' primary computing devices.

 

[ShintaiDK]

And yet the majority of phones these days (Apple excluded) are 4 cores or more- even low end phones have quad A7 clusters. And phones are arguably most peoples' primary computing devices.

But its a pure marketing gimmick. And I doubt the majority got 4 cores but rather 2. Remember all the lowend phones that massively outsell the higher end.

 

[frozentundra123456]

And yet the majority of phones these days (Apple excluded) are 4 cores or more- even low end phones have quad A7 clusters. And phones are arguably most peoples' primary computing devices.

I did specify x86. I dont see the same thing happening in the PC market because the cores are so much stronger that a dual core is more than enough for the way the vast majority of people use their computers.

 

[NTMBK]

But its a pure marketing gimmick. And I doubt the majority got 4 cores but rather 2. Remember all the lowend phones that massively outsell the higher end.

As I said, even low end phones like the Moto G have quads.

 

[ShintaiDK]

As I said, even low end phones like the Moto G have quads.

Thats closer to midrange.

 

[Cerb]

But its a pure marketing gimmick. And I doubt the majority got 4 cores but rather 2. Remember all the lowend phones that massively outsell the higher end.

They are quads. $50 tablets have them, and <=$150 phones.

Make no mistake, however: they have 4 single-issue in-order cores at 1-1.5GHz. Being quad is marketing, and is basically free in terms of die space.

 

[Lepton87]

Today is 2015 and the mainstream is 4 cores, you don't think that in 5 years time we would have 16 cores?

And in 10 years time there are enough innovations in the pipeline that even if half made it through we are going to see huge numbers of cores. Doesn't mean its going to be the same type cores as today.

This is 2009 and the mainstream is 4 cores(i5 750), don't you think in 5 years time we will have 16?

 

[TheELF]

Today is 2015 and the mainstream is 4 cores, you don't think that in 5 years time we would have 16 cores?

We would...but not in one CPU.
Look at the trend,Tv's, fridges,washingmachines,coffee makers, all come with CPU's ,in 5 years these will be fairly decent ones that will be able to interconnect into an home network with your PC at the center of it.
So you could still have a strong dual/quad core for everyday stuff and your home-network for multicore stuff.
AMD+intel don't lower wattage just for the fun of it,everybody wants a piece of this huge market that is opening up ,ARM is going strong right now but I can't see them getting fast enough to be a real thread in the long run, I mean just look at google glasses smart-watches and the whole Wearable Technology trend.

 

[III-V]

Today is 2015 and the mainstream is 4 cores, you don't think that in 5 years time we would have 16 cores?

And in 10 years time there are enough innovations in the pipeline that even if half made it through we are going to see huge numbers of cores. Doesn't mean its going to be the same type cores as today.

Nope, I think it's pretty unlikely. There are more important things to spend that transistor budget on. Most consumers would likely be more interested in saving a bit of money over higher core counts as well... and the software development bottleneck is not going to go away within that timeframe either.

 

[Ramses]

http://www.federalnewsradio.com/pdfs/IntelMulti-CoreProcessors.pdf

Not new but interesting, they echo a lot of what's been said here.

 

[imported_ats]

And yet the majority of phones these days (Apple excluded) are 4 cores or more- even low end phones have quad A7 clusters. And phones are arguably most peoples' primary computing devices.

And most phones basically don't ever use more than a single core. Pretty much anyone selling a phone these days with more than 2 cores is trying to con their potential customers. All 4 cores in a phone does is suck down more power and deliver slower performance (esp considering most SoCs are in the stone ages as far as power management). There is a reason that the only phone maker that doesn't have to market on raw specs still only uses 2 cores.

Basically, there aren't really that many things that people do that can readily take advantage of more than 1-2 cores. Going to 2 hardware contexts gets you over the responsiveness hump, beyond that, esp for phone, its just wasted silicon. They would be better off using that are for more cache, better accelerators, or better GPUs.

 

[NTMBK]

And most phones basically don't ever use more than a single core. Pretty much anyone selling a phone these days with more than 2 cores is trying to con their potential customers. All 4 cores in a phone does is suck down more power and deliver slower performance (esp considering most SoCs are in the stone ages as far as power management). There is a reason that the only phone maker that doesn't have to market on raw specs still only uses 2 cores.

Basically, there aren't really that many things that people do that can readily take advantage of more than 1-2 cores. Going to 2 hardware contexts gets you over the responsiveness hump, beyond that, esp for phone, its just wasted silicon. They would be better off using that are for more cache, better accelerators, or better GPUs.

A couple of threads for the web browser app (UI inputs on one thread, loading and render calls on the other), thread for OS and I/O, thread for the garbage collector to do its thing. Or maybe you are downloading a file in the background, or updating an application, or playing back music while reading a website. Hey presto, 4 threads utilised. Not all loaded all the time, but that doesn't really matter- having the extra cores there reduce the number of unexpected latency spikes and greatly improves the user experience.

And come on, these cores are a very small part of your smartphone SoC. Here's an overview of the Snapdragon 605:

And that is Krait, an out of order core which is much larger than the Cortex A7. A cluster of four of them is still less than a quarter of the die- significantly more space is dedicated to the fixed-function multimedia accelerators. Putting in 2 extra cores isn't going to blow the budget.

 

[ninaholic37]

http://www.federalnewsradio.com/pdfs/IntelMulti-CoreProcessors.pdf

Not new but interesting, they echo a lot of what's been said here.

Interesting how they were already focusing on Quad Cores in 2006.

Their conclusion was amusing:

"Think of a time a decade or so from now when the full power of high performance computing and parallel processing is available to computer users everywhere, and it might be possible to hold the power of a computer with hundreds of execution cores in the palm of your hand."

...nope, still 4 cores.

 

[Enigmoid]

A couple of threads for the web browser app (UI inputs on one thread, loading and render calls on the other), thread for OS and I/O, thread for the garbage collector to do its thing. Or maybe you are downloading a file in the background, or updating an application, or playing back music while reading a website. Hey presto, 4 threads utilised. Not all loaded all the time, but that doesn't really matter- having the extra cores there reduce the number of unexpected latency spikes and greatly improves the user experience.

Really? Apple has a problem with latency spikes and user experience?

 

[TheRyuu]

Today is 2015 and the mainstream is 4 cores, you don't think that in 5 years time we would have 16 cores?

We already have 16 core cpu's. You just have to look where they're popular.

Hint: It's not your desktop (Linus talked about this in that ML thread if you read it).

 

[NTMBK]

Really? Apple has a problem with latency spikes and user experience?

No, but notice I was talking about Android. Garbage collection should have been a giveaway. Apple's software stack is optimized for their fixed hardware.

 

[Enigmoid]

No, but notice I was talking about Android. Garbage collection should have been a giveaway. Apple's software stack is optimized for their fixed hardware.

And adding more cores is a penny wise pound foolish method of doing so.

Ie Samsung should fix the terrible issues with Touchwiz rather than throwing more cores at it.

Anyway right now on my laptop I have 1521 threads on a 4C/8T CPU. There is not problem in response or user experience.

 

[III-V]

And come on, these cores are a very small part of your smartphone SoC. Here's an overview of the Snapdragon 605:

That chart, and most core floorplan diagrams like it, are complete fabrications. That particular image is... well... horrendously inaccurate, to say the least.

Here's their Snapdragon 800... correctly labeled:

The CPU takes up a significant portion of the die. I'd imagine its share is decreasing over time, but it's not trivial.

 

[Nothingness]

Anyway right now on my laptop I have 1521 threads on a 4C/8T CPU. There is not problem in response or user experience.

I bet >1500 of these threads are sleeping. I can guarantee you that if they were all active your system would not be usable.

 

[imported_ats]

A couple of threads for the web browser app (UI inputs on one thread, loading and render calls on the other), thread for OS and I/O, thread for the garbage collector to do its thing. Or maybe you are downloading a file in the background, or updating an application, or playing back music while reading a website. Hey presto, 4 threads utilised. Not all loaded all the time, but that doesn't really matter- having the extra cores there reduce the number of unexpected latency spikes and greatly improves the user experience.

Any none of that needs more than two or will even show a performance improvement with more than 2. And quite likely will actually show a degradation with more than 2. 2 cores running faster will generally perform better and have overall lower power than 4 running slower. I won't even get into the differentials when you trade 2 strong core designs for 4 weak ones. Do I really need to point out that Apple with 2 cores basically trounces everyone else out there on both objective and subjective latency metrics?

And come on, these cores are a very small part of your smartphone SoC. Here's an overview of the Snapdragon 605:

It doesn't matter how big or small they are. They could be .000001mm^2 and it still wouldn't matter. Unless the cores are actively contibuting to an improved end user experience it is a waste to include them, and the reality is that they aren't improving the end user experience. They are there just for specification based marketing.

 

[imported_ats]

That chart, and most core floorplan diagrams like it, are complete fabrications. That particular image is... well... horrendously inaccurate, to say the least.

Here's their Snapdragon 800... correctly labeled:

The CPU takes up a significant portion of the die. I'd imagine its share is decreasing over time, but it's not trivial.

Yep, replacing 2 of those cores with simple cache would probably result in much better performance.

 

[TheELF]

I bet >1500 of these threads are sleeping. I can guarantee you that if they were all active your system would not be usable.

Well duh...That's the whole point of threading,running pieces of code only if and when they have to run and not all the time,this is the same in general software as well as games.

 

[Nothingness]

Well duh...That's the whole point of threading,running pieces of code only if and when they have to run and not all the time,this is the same in general software as well as games.

Indeed, and that's why I think the number of process can't be used to guess the required/comfortable number of cores