Why not have one main core and many smaller sub-cores?

[eastnileuc]

It seems that in multi-core CPUs, all of the cores are the same. But usually, only one core is used, with multicore processing reserved for certain software/operations. Since this is the most common use case, wouldn't large speedups be possible with one powerful "main core" that does single core work, with smaller "subcores" turned on for multicore workloads? This seems more suitable than having all of the same cores be of the same power level.

[Himommies]

1 minute ago, eastnileuc said:

It seems that in multi-core CPUs, all of the cores are the same. But usually, only one core is used, with multicore processing reserved for certain software/operations. Since this is the most common use case, wouldn't large speedups be possible with one powerful "main core" that does single core work, with smaller "subcores" turned on for multicore workloads? This seems more suitable than having all of the same cores be of the same power level.

You are describing a GPU

[79wjd]

That's a thing on ARM known as bigLITTLE, but more powerful cores aren't really possible right now, and since power consumption isn't a serious concern on computers, it's not deemed worthwhile to waste time with weak cores for light tasks (when the main cpu can just downclock itself). 

[eastnileuc]

Just now, Himommies said:

You are describing a GPU

But in GPU there's thousands of cores, with no emphasis on "single core" work, ever.

[Himommies]

Just now, eastnileuc said:

But in GPU there's thousands of cores, with no emphasis on "single core" work, ever.

That's when your CPU comes in

[airdeano]

welcome to the Linus Tech Tips forums.

already being done. ARM processors do single, dual, quad to allow intensive tasks needing power get assignments and the smaller take care of smaller scheduled tasks.

power savings in a small package.

 

https://en.wikipedia.org/wiki/ARM_big.LITTLE

[eastnileuc]

1 minute ago, airdeano said:

welcome to the Linus Tech Tips forums.

already being done. ARM processors do single, dual, quad to allow intensive tasks needing power get assignments and the smaller take care of smaller scheduled tasks.

power savings in a small package.

But such processors are uncommon. Why no mainstream adoption (Intel & AMD)?

[airdeano]

its been a practice for seven years already.

theyve been in a major portion of cellular industry and small agile compuations.

current mainstream has the same potentials, just that programming developers rather program at one task and allow the OS dictation of 'importance'.

seeing in other programming, as spreadsheets, photo manipulations and other apps do similar.

[Himommies]

4 minutes ago, eastnileuc said:

But such processors are uncommon. Why no mainstream adoption (Intel & AMD)?

Who would buy it?

[TheRandomness]

14 minutes ago, eastnileuc said:

But such processors are uncommon. Why no mainstream adoption (Intel & AMD)?

The complexity of the design would skyrocket the price. Also, you're basically describing a CPU/GPU combo, or a Xeon Phi in a system.

[Pip313]

As others have pointed out we basically do have that already in desktops. Except that one main core is really however many main cores your cpu has and the smaller many cores is the gpu.

 

What you’re trying to say is have smaller cores that programmers can specifically program for. And that is done with gpu’s when needed.

 

Really you’re just overthinking it, trying to make things complicated unnecessarily. Why add smaller weaker cores to cpu’s when you can have full size ones? 4,6,8 core cpu’s are mainstream now and aren’t even being fully utilized. The idea we need even more cpu cores that are actually weaker isn’t based on actual real world need.

[Mira Yurizaki]

Such processors already exist in the mobile space. But here it makes sense to do it, mainly for background tasks and other lower demanding ones that need to run while the device is asleep.

 

This setup doesn't really offer much of a benefit in the desktop space because you basically have unlimited power anyway. Laptops might benefit from it, but at the same time, the efficiency of CPUs for laptops is good enough anyway to match a mobile one in its entirety.

 

Note that if the processor has enough IPC performance, it can beat out any multicore processor anyway.