Linux Kernel Sees Initial Patches For Supporting Intel Hybrid CPUs

[phoronix]

Phoronix: Linux Kernel Sees Initial Patches For Supporting Intel Hybrid CPUs

Intel engineers today sent out their initial Linux kernel patches for bringing up the company's forthcoming hybrid architecture processors...

http://www.phoronix.com/scan.php?page=news_item&px=Linux-Kernel-Intel-Hybrid-CPUs

[Ironmask]

Wow, first time I heard of this hybrid architecture thing. So let me get this straight, x86 is such a bloated mess and Intel is so bad at making CPUs that they have to put a little, less garbage CPU inside of their big CPU because it uses so much power and creates so much heat that it's understandably non-viable for any applications that aren't desktop workstations. Is this how they're competing with ARM? This is just sad.

You don't need a hybrid CPU, you shouldn't need a hybrid CPU. Hybrid cars? Okay, there's some laws of physics going on there where those make sense. Hybrid CPU? That's just compensating for a garbage architecture. That's like making a big, bloated mail app and then a less featureful mail app and telling customers to use the one with less features if they're constrained on time and don't feel like waiting for the larger app to load. Calling this a bandaid solution would be a compliment.

God, I hate Intel.

[Gusar]

Ironmask This design actually comes from the ARM world! Pretty much every mobile device since a few years has a few high performance, high power consumption cores and a few slower, really energy efficient cores.

[boxie]

Wow, first time I heard of this hybrid architecture thing. So let me get this straight, x86 is such a bloated mess and Intel is so bad at making CPUs that they have to put a little, less garbage CPU inside of their big CPU because it uses so much power and creates so much heat that it's understandably non-viable for any applications that aren't desktop workstations. Is this how they're competing with ARM? This is just sad.

You don't need a hybrid CPU, you shouldn't need a hybrid CPU. Hybrid cars? Okay, there's some laws of physics going on there where those make sense. Hybrid CPU? That's just compensating for a garbage architecture. That's like making a big, bloated mail app and then a less featureful mail app and telling customers to use the one with less features if they're constrained on time and don't feel like waiting for the larger app to load. Calling this a bandaid solution would be a compliment.

God, I hate Intel.

There are a bunch of physics at play here too. If you design your CPU to be really energy efficient you end up not having lots of CPU grunt - but you can run off the whiff of an electron. On the other hand, you can add lots of features to your CPU to make it faster at running, but at the expense of having more circuitry - which takes (you guessed it) more energy to run.

big.LITTLE is the arm worlds attempt at having their cake and eat it too, Intel are doing it with Lakefield.

Hybrid x86 is genuinely interesting (from a hardware PoV), and Lakefield is also interesting with the 3D packaging.

now - Intel have been stagnant for a long time and it will take a lot of effort over many more years yet for them to get out of the current quagmire they are in, but - they will get there. I am sure they will solve their manufacturing issues, they will have had a bonfire lit underneath them now that AMD are once again providing competition.

As someone who is on the AMD side of the fence I hope Intel get back on track. Competitive pressure only means good things for me, the end consumer!

I hope AMD find new ways of lowering their power consumption too - they are doing a good job atm, but can still going further

[Duve]

There are a bunch of physics at play here too. If you design your CPU to be really energy efficient you end up not having lots of CPU grunt - but you can run off the whiff of an electron. On the other hand, you can add lots of features to your CPU to make it faster at running, but at the expense of having more circuitry - which takes (you guessed it) more energy to run.

big.LITTLE is the arm worlds attempt at having their cake and eat it too, Intel are doing it with Lakefield.

Hybrid x86 is genuinely interesting (from a hardware PoV), and Lakefield is also interesting with the 3D packaging.

now - Intel have been stagnant for a long time and it will take a lot of effort over many more years yet for them to get out of the current quagmire they are in, but - they will get there. I am sure they will solve their manufacturing issues, they will have had a bonfire lit underneath them now that AMD are once again providing competition.

As someone who is on the AMD side of the fence I hope Intel get back on track. Competitive pressure only means good things for me, the end consumer!

I hope AMD find new ways of lowering their power consumption too - they are doing a good job atm, but can still going further

That's the thing, hybrid CPUs aren't particularly new. All of them tend to grapple with the question of how do you produce a CPU unit with lots of features and that can sip energy.

big.LITTLE has been a fairly successful attempt at this, with one odd exception. This is something that hasn't translated to arm server exploits, were power efficiency and high feature sets is a requirement. That said I don't know of a smartphone CPU that doesn't have the setup.

Nice to see this isn't the only thing that Intel is learning, I'm still wondering about their exploits on 3D stacking dies since that requires modularity. Intel it's not really good at that at the die level simply because they haven't required it, but Ryzen has opened the idea of modular chipsets will wide open because their chiplets have served them well.

[AdrianBc]

Wow, first time I heard of this hybrid architecture thing. So let me get this straight, x86 is such a bloated mess and Intel is so bad at making CPUs that they have to put a little, less garbage CPU inside of their big CPU because it uses so much power and creates so much heat that it's understandably non-viable for any applications that aren't desktop workstations. Is this how they're competing with ARM? This is just sad.

You don't need a hybrid CPU, you shouldn't need a hybrid CPU. Hybrid cars? Okay, there's some laws of physics going on there where those make sense. Hybrid CPU? That's just compensating for a garbage architecture. That's like making a big, bloated mail app and then a less featureful mail app and telling customers to use the one with less features if they're constrained on time and don't feel like waiting for the larger app to load. Calling this a bandaid solution would be a compliment.

God, I hate Intel.

Older Intel CPUs up to 14 nm, i.e. up to Comet Lake, do not really need to use a BIG + LITTLE combination, like in the ARM smartphone CPUs.

The reason is that those Intel CPUs can work in a very extended range of power supply voltages and clock frequencies, allowing the variation of the power consumption in a huge range.

For example a Coffee Lake CPU that I have can work at a clock frequency range between 0.5 and 4.5 GHz, i.e. a 1:9 ratio, with the power consumption varying between less than 0.5 W and 50 W, i.e. in an 1:100 ratio.

I do not know for sure, but it seems that the more recent manufacturing processes no longer allow such a large range for supply voltages, therefore also for clock frequencies. At least a 7 nm Ryzen that I have varies the clock frequency only in an 1:4 ratio, compared to the 1:9 ratio available with the older Intel.

When only a more limited range of voltages & frequencies is available, then one really needs a BIG+LITTLE CPU combination in order to have a good energy efficiency for running all the tasks that do not require maximum performance.

I believe that this is the reason why Intel is transitioning to a hybrid architecture for their laptop and desktop CPUs. This problem does not appear for servers, which have a much less variable computing load, so for those a large number of identical cores will remain best.

Of course, even if this supposition is true, that does not exclude as a big motivation for the Intel Alder Lake to be able to advertise it as a 16-core CPU (i.e. 8 big + 8 little), in the competition with the 16-core Ryzen 5xxx CPUs.

[numacross]

I do not know for sure, but it seems that the more recent manufacturing processes no longer allow such a large range for supply voltages, therefore also for clock frequencies. At least a 7 nm Ryzen that I have varies the clock frequency only in an 1:4 ratio, compared to the 1:9 ratio available with the older Intel.

I'm pretty sure that 7nm Ryzen is only reporting the lowest frequency step (the lowest ACPI power state), but actually goes into deep power saving state internally when this happens. HWiNFO on Windows can estimate the real clock rate for this state, but the actual algorithm is known only to AMD.

Comparing self-reported values for AMD and Intel doesn't provide much insight. They use vastly different architectures not only in cores and their periphery but power deliver systems as well. External independent measurements are the only way to go, but there still will be variance due to motherboard construction.

[pmorph]

You don't need a hybrid CPU, you shouldn't need a hybrid CPU.

Not that I like the idea much myself, but that seems like a weird statement to make at this point. it either works or doesn't work, which remains to be seen.

[jaxa]

Not that I like the idea much myself, but that seems like a weird statement to make at this point. it either works or doesn't work, which remains to be seen.

It didn't work out that well with the expensive Lakefield chips, although maybe drivers have improved since launch.

Funny that ARM is having to move in the opposite direction with the Cortex-X1 core, which is higher performance, lower efficiency, and physically larger than the A-series performance cores. But it's worth it to do this if only 1 or 2 are used per cluster, since single-threaded performance improves and a mix of Cortex-X1, Cortex-A78, and Cortex-A55 offers better performance and efficiency as needed.

At AMD, the Zen 2 cores are already so small and efficient that they can just pack 8 cores into 15 W Renoir and call it a day. One core can do more work than the others. It's unclear that AMD will want to pursue a hybrid design when they can just put 8, 12, or 16 cores into an increasingly smaller area with each major die node shrink.

Alder Lake will give Intel another chance to get hybrid x86 right, but I'm already not a fan of the configuration. They could use the small size of the Atom cores to fit in 8+16 or 8+32 in order to pose a real challenge to the Ryzen 9 3950X and 5950X. Bump up the Atom core count even more while keeping a few big cores, and it could take on Threadripper and Epyc in certain tasks. Intel did kill its Xeon Phi lineup of high core count Atom CPUs, but those specifically had AVX-512 support, which might not be coming to Atom again (to keep the size small).

[boxie]

That's the thing, hybrid CPUs aren't particularly new. All of them tend to grapple with the question of how do you produce a CPU unit with lots of features and that can sip energy.

big.LITTLE has been a fairly successful attempt at this, with one odd exception. This is something that hasn't translated to arm server exploits, were power efficiency and high feature sets are requirement. That said I don't know of a smartphone CPU that doesn't have the setup.

Nice to see this isn't the only thing that Intel is learning, I'm still wondering about their exploits on 3D stacking dies since that requires modularity. Intel it's not really good at that at the die level simply because they haven't required it, but Ryzen has opened the idea of modular chipsets will wide open because their chiplets have served them well.

yeah, hybrid solves the power limited environment stuff nicely - it'll be interesting to see how long it takes Intel to get it "right"

There are lots of ARM setups without big.LITTLE - namely everything without the big part (lots of quad and octa A53 setups)

I too look forward to seeing how AMD continues develops its tech. laptops are a huge market, so I am guessing there is gonna be quite a lot more innovation in power efficiency there too.