New cores (A15)

[Populus]

But, do you think the M2 in 2022 (not the M1X for the next MBPs) will use the A15 as a base architecture, plus built at 3nm like the rumors say? Or will the M2 be based on the future architecture of an hypothetical A16?

I know I’m talking about 2022 products and it is all mere speculation, but still.

 

[cmaier]

But, do you think the M2 in 2022 (not the M1X for the next MBPs) will use the A15 as a base architecture, plus built at 3nm like the rumors say? Or will the M2 be based on the future architecture of an hypothetical A16?

I know I’m talking about 2022 products and it is all mere speculation, but still.

I still think that the M2 is coming next month, not 2022, but who knows.

 

[dgdosen]

All these rumors that highlight Apple's brain drain make following these chip changes much more dramatic than anything on AppleTV+

 

[cmaier]

All these rumors that highlight Apple's brain drain make following these chip changes much more dramatic than anything on AppleTV+

I am pretty sure there hasn’t been much of a brain drain in the CPU group. Just checking my linkedin contacts, all the excellent chip designers I know are still there, other than Manu Gulati (who was a co-TLM lead with me at AMD).

 

[rme]

I still think that the M2 is coming next month, not 2022, but who knows.

Hard to believe they'll go to armv9 for the MacBook first, no?

 

[Populus]

We still don’t know if A15 is armv9...

 

[cmaier]

Hard to believe they'll go to armv9 for the MacBook first, no?

We don’t know what chip will have armv9, if any, and why shouldn’t they go to the MacBook first? The v9 differences aren’t going to make any difference in an iPhone.

 

[Biritto]

What about RAM? Has anyone seen any information whether it is lpddr5? Not as important as pure capacity for my use case, but it’s not something to set aside.

 

[rme]

We don’t know what chip will have armv9, if any, and why shouldn’t they go to the MacBook first? The v9 differences aren’t going to make any difference in an iPhone.

Seems to me Apple decided to delay the move to v9 to 2022.
The confidential compute architecture could be useful in phones.

 

[cmaier]

Seems to me Apple decided to delay the move to v9 to 2022.
The confidential compute architecture could be useful in phones.

I’m not sure it’s all that helpful given the security stuff already in the A-series, but what I think doesn’t matter.

 

[Macintosh IIcx]

Here’s a random thought - could the A15 cores be, essentially, simply revs of Firestorm and Icestorm, with the same microarchitecture and some minor improvements? Maybe they increased the sizes of the caches and SLC - that could account for, say, 10% of the increased transistor count. Then you have the extra GPU core, for another 5% - maybe more if the GPUs are redesigned. Maybe the neural engines were completely redone. Tough to figure out how to add up to 3 billion more transistors. But, anyway, perhaps they’ve decided to decouple the i-device and Mac CPUs, so the M2 is not using the same cores as the A15? It would make a certain amount of sense - the A-series now go only into phones and lower-end ipads, where the CPU performance has more or less become “more than good enough” and where the focus is on other functional blocks (GPU, neural engine, image processing, etc.) to support things like the upcoming VR goggles, etc.

Anyway, just random thoughts. I’ve certainly worked on a lot of chips where we got 10-15% improvement without ripping up the core microarchitecture. And if there was an entirely new design, I feel like Apple might have spent a bunch of time talking about how great it is. Now I feel like we will get our next CPU brag from Apple in a few weeks at the mac announcement.

Thinking a bit about it, there is also the simple explanation that most of the CPU team has been working on the M2 CPU architecture instead the past year if Apple thought that they had to go in a bit different direction than with Firestorm CPU. So only a few was working on tweaking the CPU for A15 slightly ?

 

[Macintosh IIcx]

We still don’t know if A15 is armv9...

Wasn’t the specifications just finalized March this year? I can’t see them having this implemented in CPU design so fast. Maybe next year. But maybe Apple’s instruction set is already customized enough so they don’t need ARM v9?

 

[cmaier]

Thinking a bit about it, there is also the simple explanation that most of the CPU team has been working on the M2 CPU architecture instead the past year if Apple thought that they had to go in a bit different direction than with Firestorm CPU. So only a few was working on tweaking the CPU for A15 slightly ?

That’s certainly a common phenomenon. At AMD, I would sometimes be working on the “plus” version of chips at the same time a whole new chip was spinning up (or vice versa). At various points one team or the other has more people, depending on what has to be done.

What’s interesting is that the N5p node probably required very little work to port to.

Anyway, all this speculation is making me crazy.

 

[Populus]

Crazy in the good sense or in the bad sense?
I enjoy all this speculation

 

[Kpjoslee]

I am pretty sure there hasn’t been much of a brain drain in the CPU group. Just checking my linkedin contacts, all the excellent chip designers I know are still there, other than Manu Gulati (who was a co-TLM lead with me at AMD).

Hmm, well, I think a brain drain still happened when some key people left to form Nuvia back in 2019. Though it is still a speculation if that affected their roadmap a bit

 

[Jorbanead]

That’s pure speculation. Another theory is that Apple went for efficiency gains rather than performance. I don’t think anyone is clamoring for more CPU speed in an iPhone.

This is my theory. They added a brighter screen with 120Hz refresh rate, added real-time bokeh to video (probably using a new neural engine core design?), while still adding hours of battery life. Seems battery and other non-cpu related improvements were the focus this time.

"It appears Apple has not changed the CPU much this generation. SemiAnalysis believes that the next generation core was delayed out of 2021 into 2022 due to CPU engineer resource problems. In 2019, Nuvia was founded and later acquired by Qualcomm for $1.4B. Apple’s Chief CPU Architect, Gerard Williams, as well as over a 100 other Apple engineers left to join this firm. More recently, SemiAnalysis broke the news about Rivos Inc, a new high performance RISC V startup which includes many senior Apple engineers. The brain drain continues and impacts will be more apparent as time moves on. As Apple once drained resources out of Intel and others through the industry, the reverse seems to be happening now.

We believe Apple had to delay the next generation CPU core due to all the personnel turnover Apple has been experiencing."

Apple CPU Gains Grind To A Halt And The Future Looks Dim As The Impact From The CPU Engineer Exodus To Nuvia And Rivos Starts To Bleed In

Apple's leading CPU team looks to be struggling as they have now delivered no CPU gains for the first generation ever. Apple likely had to delay their next core architecture due due to personnel overturn from the Nuvia exodus. Furthermore, with a new exodus surrounding Rivos, the future doesn't...

semianalysis.substack.com

M1 Exploration - v 0.70

M1 Explainer 070.pdf

drive.google.com

Another factor is maybe Apple is putting more of their talent into the Mac line of chips. CPU speeds for the iPhone are plenty capable at this point, so it would make sense for the top engineers to focus more on the new Mac chips, especially if they’re working on extremely high end Mac Pro level chips.

 

[cmaier]

Hmm, well, I think a brain drain still happened when some key people left to form Nuvia back in 2019. Though it is still a speculation if that affected their roadmap a bit

Those people were not very key. And that’s not how chip design works - a few people leaving isn’t going to derail things.

 

[crazy dave]

Wasn’t the specifications just finalized March this year? I can’t see them having this implemented in CPU design so fast. Maybe next year. But maybe Apple’s instruction set is already customized enough so they don’t need ARM v9?

It would be a touch fast. But given that ARMv9 is less of a jump than from 7 to 8 and that Apple is usually quick off the mark, people thought it might come this year. A lot of 9 is mandating optional stuff in 8 plus extra security and vector instructions. I believe like Apple’s AMX there may be matrix instructions too but I can’t remember and even if so I don’t think if anyone knows how close the two are. The new vector instructions though are said to be very nice (which would be good mostly for the Mac side but I’m sure some i-device devs wouldn’t mind having them either).

 

[Kpjoslee]

Those people were not very key. And that’s not how chip design works - a few people leaving isn’t going to derail things.

According to the article, it wasn't a few people but over a 100 engineers along with them. Like I said, it is a speculation but not really far fetched. They left just in time when Apple begun to expend their SoC lineup to Macs.

 

[crazy dave]

Those people were not very key. And that’s not how chip design works - a few people leaving isn’t going to derail things.

I think a sub stack article said 100 people have been lost from Apple to Nuvia and there’s a new one too formed from ex-Apple engineers. Don’t know where they got the numbers from or if all of them were cpu team/support.

Apple CPU Gains Grind To A Halt And The Future Looks Dim As The Impact From The CPU Engineer Exodus To Nuvia And Rivos Starts To Bleed In

Apple's leading CPU team looks to be struggling as they have now delivered no CPU gains for the first generation ever. Apple likely had to delay their next core architecture due due to personnel overturn from the Nuvia exodus. Furthermore, with a new exodus surrounding Rivos, the future doesn't...

semianalysis.substack.com

According to the article, it wasn't a few people but over a 100 engineers along with them. Like I said, it is a speculation but not really far fetched. They left just in time when Apple begun to expend their SoC lineup to Macs.

Link above. Grain of salt needed though. Unsure where the numbers come from or how many were on the cpu team. First time hearing it was this big. Though I suppose Apple is pissed at GW3 for hiring people away for a reason …

 

[cmaier]

According to the article, it wasn't a few people but over a 100 engineers along with them. Like I said, it is a speculation but not really far fetched. They left just in time when Apple begun to expend their SoC lineup to Macs.

I don’t believe the article. A ton of folks I used to work with are still there - these are folks with decades of experience. CPU Implementation Leads, Verification Manager, Power Optimization Lead, Director Custom Silicon Management, etc. All still there.

 

[aeronatis]

I believe the lack of CPU speed improvements can be explained by A15 focusing on battery life instead of absolute performance. They already outperform anyone else, it makes sense to slightly lower the clocks/use less aggressive power curve.

Could it be that they use a lower clocked A15 on iPad Min just so it would not overpower iPad Air? That still wouldn't explain the reason they use 5-core GPU though ?

 

[JMacHack]

Wait for benchmarks(tm)

 

[leman]

Could it be that they use a lower clocked A15 on iPad Min just so it would not overpower iPad Air? That still wouldn't explain the reason they use 5-core GPU though ?

Because if they are using the binning approach people think they are using, that 5-core GPU might consume as much power as the 4-core one.

 

[Lemon Olive]

A15 has the same core configuration (2+4) as A14, which suggests to me that they are of similar relative complexity as Firestorm vs. IceStorm, and the new high performance cores aren’t hardware-multithreaded. Which suggests to me that rumors of 8+2 or 10+2 for M1X/m2 are likely not right. Rumors only made sense if the cores were radically different in relative performance - either the low power cores can handle more pipelines or the high power cores can multi thread to compensate for blocking low priority threads. Based on all that, I doubt the 8+2/10+2 rumors. Also means that the new MBPs coming next month may indeed have M1X instead of M2(x).

YOU DON'T SAY. I've only been telling you this for months.