8 ms·

With all the discussion about what the “big trick” is that makes the M1 seem to be such a breakthrough, I can’t help but wonder, if the M1 is more like the iPho

With all the discussion about what the “big trick” is that makes the M1 seem to be such a breakthrough, I can’t help but wonder, if the M1 is more like the iPhone: The sum of a large number of small engineering improvements, coupled with a lot of component integration detail work, topped off by some very shrewd supply chain arrangements. Analogous to the iPhone being foreshadowed by the iPod without most experts believing Apple could make a mobile phone from that, the M1 was foreshadowed by the A1 for mobile devices with many(most?) experts not forecasting how much it could be the base for laptops and desktops. It seems, the M1 includes numerous small engineering advances and the near term lockup of the top of the line fab in the supply chain also reminds me of how Apple had secured exclusivity for some key leading edge iPhone parts (was it the screens?). So the M1 strikes me as the result of something that Apple has the ability to pull off from time to time. And that is rather hard to pull off financially, organizationally and culturally. And it more than makes up for some pretty spectacular tactical mis-steps (I’m looking at you, puck mouse, cube mac, butterfly keyboard). EDIT for typo

jolux 6y ago
The first A-series chip was the A4, because it came out with the iPhone 4.
alwillis 6y ago
So the M1 strikes me as the result of something that Apple has the ability to pull off from time to time. Perhaps you haven't been paying attention? Apple shipped 64-bit ARM processors for the iPhone at least a year before Qualcomm could do it for Android devices. The reaction to the A7 was similar to what we're seeing now with the M1—not possible, there's some trickery going on, etc. Apple is pretty good at this processor transition thing, going from 68k to PowerPC to Intel to ARM. And it more than makes up for some pretty spectacular tactical mis-steps (I’m looking at you, puck mouse, cube mac, butterfly keyboard). Except for the recent keyboard issues, you're literally talking about another era. I wouldn't put the shape of the mouse for the 1998 iMac in the same category as transitioning a $9 billion revenue product line to a radically different processor architecture.
- dwighttk 6y ago
  > not possible, there's some trickery going on “...and even if they did it, it doesn’t matter” (though I guess not many are saying that about M1)
  - alwillis 6y ago
    Yes—there was a lot of “it won’t matter” talk when the A7 shipped.
- hajile 6y ago
  > Apple shipped 64-bit ARM processors for the iPhone at least a year before Qualcomm could do it for Android devices. The reaction to the A7 was similar to what we're seeing now with the M1—not possible, there's some trickery going on, etc. That is because it is not possible to ship a top-end design for a new ISA in that amount of time. The more reasonable answer is they had been working on a new core design for some years before. AMD has hinted that their Zen design makes it relatively easy to swap the x86 frontend for an ARM frontend. Apple was considering buying MIPS around that time. I suspect they strong-armed ARM into accepting their ARMv8 proposal because it was good and because Apple buying MIPS would be disastrous for ARM's share price. At that point, it wasn't faster than possible, it was just designing the last part of the chip (or if both frontends were being worked on in tandem, cancelling one of them and focusing everyone on the other). This explains why ARM announced v8 and then took the full 4 years to ship their first low-power core (A53) and even longer to ship their bad first try at a high-performance core (A57 -- with the more baked A72 being superior in almost every way).
- DonHopkins 6y ago
  Don't forget Apple's first transition from 6502 to 68k. That was pretty bumpy though.
  - alwillis 6y ago
    I was only talking about the Mac, which never used the 6502–that was the Apple II. The Apple IIgs did end up on the 65816.
simonh 6y ago
Apple has used exclusive access to advanced hardware as a differentiator several times. With screens it was Retina. They funded the development and actually owned the manufacturing equipment and leased it to the manufacturing subcontractors. Also in 2008 they secured exclusive access to a then new laser cutting technology that they used to etch detail cuts in the unibody enclosures of their MacBooks, and then iPads. This enables them to mill and then precision cut the device bodies out of single blocks of Aluminium. They’ve also frequently bought small companies to secure exclusive use of their specialist tech, like Anobit for their flash memory controllers, Primesense for the face mapping tech in FaceID, and there are many more. For Apple simply having the best isn’t enough, they want to be the only people with the best.
- FullyFunctional 6y ago
  They bought Intrinsity as well, leaving us wonder about the fate of Fast14.
- vizzier 6y ago
  I believe this is the only consumer 5nm chip currently available as well. Ryzen gen 3 is still on 7nm. I'd be interested to see how well general purpose compute on the m1 vs ryzen gen 3 mobile will be.
  - leecb 6y ago
    The Huawei Mate 40 came out two months ago, and uses the Hisilicon Kirin 9000, which is also on TSMC's 5nm. It has about 30% more transistors and a higher clockspeed than the A14.
    - AsyncAwait 6y ago
      AMD has substantially more CPU/Microarch design experience.
    - 1123581321 6y ago
      Would you say that the comparison to the A13 from this article is fair? https://www.notebookcheck.net/HiSilicon-Kirin-9000-Processor-Benchmarks-and-Specs.505389.0.html https://www.notebookcheck.net/HiSilicon-Kirin-9000-Processor...
_ph_ 6y ago
The sum of a large number of small engineering improvements, coupled with a lot of component integration detail work, topped off by some very shrewd supply chain arrangements. I think you precisely have it. There is no single magic reason the M1 is so good, just a lot of things coming together. They start with a better instruction set than x86, have of course the best process available, and perhaps the largest part, they have built up an increadible team over a decade. And they are extremely focussed in what they target. If anything, that is Apples "magic". They are not making a chip which is built in an abstract manner to be sold to random customers. They have exactly their needs in mind and execute towards those. In a sense AMD did that with the chips for the Playstation/XBox. Like the M1 it is basically a SOC. There optimized for great graphics performance. Unfortunately, those chips are not sold separately for building your own PC.
deleted 6y ago
[deleted]
gchadwick 6y ago
> The sum of a large number of small engineering improvements, coupled with a lot of component integration detail work, topped off by some very shrewd supply chain arrangements. I think the vertical integration they have is a major advantage too. I used to work at arm on CPUs. One thing I worked on was memory prefetching which is critical to performance. When designing a prefetcher you can do a better job if you have some understanding or guarantees as to the behaviour of the wider memory system (better yet if you can add prefetching specific functionality to it). The issue I faced is the partners (Samsung, Qualcomm etc) are the ones implementing the SoC and hence controlling the wider memory system. They don't give you detailed specs of how that works, nor is there an method where you can discuss with them appropriate ways to build things to enable better prefetching performance. You end up building something that's hopefully adaptable for multiple scenarios and no one ever gets a chance to do some decent end to end performance tuning. I'm either working with a model of what the memory system might be and Qualcomm/Samsung etc engineers are working with the CPU as a black box trying to tune their side of things to work better. Were we all under one roof I suspect we could easily have got more out of it. You also get requirements based upon targets to hit for some specific IP, rather than requirements around the final product, e.g. silicon area. Generally arm will be keen to keep area increase low or improve performance / area ratio without any huge shocks on overall area. If you're apple you just care about the final end user experience and the potential profit margin. You can run the numbers and realise you can go big on silicon area and get where you want to be. With a multi-company/vendor chain each link is trying to optimise for some number they control, even if that overal has a negative impact on the final product.
- fluffy87 6y ago
  Nvidia makes arm processors, GPUs and SoCs, so this integration will be good for them if the arm sale is approved.
- socialdemocrat 6y ago
  Very interesting comment. I mean you see some of the same things with companies like Tesla also pushing vertical integration. A lot of the examples you see are similar to what you talk about. You can cut down on the friction between different parts. I remember an example of software controlling a blinking icon on the dashboard, where this was a 10 minute code change for Tesla but a 2-3 month update cycle for a traditional automaker due to the dashboard hardware coming from a supplier.
scottlocklin 6y ago
I haven't studied it carefully, but it sure looks like 90% of the performance improvement is using a big cache, which is a totally obvious thing to do. Also the big x86 guys have more or less been asleep at the wheel for almost a decade. My go to example: my 2011 x220 sandybridge stinkpad is faster than my 2017 kaby lake mbp. 2005 machines (I dunno, Lakeport?) aren't even in the same ballpark as modern machines. Had that pace continued up to current year, the M1 chip would be a stinker. As it is, AMD is close and could smoke M1 in next generation 5nm chips, restoring order to the universe.
- CrazyStat 6y ago
  >As it is, AMD is close and could smoke M1 in next generation 5nm chips, restoring order to the universe. Comparing next gen to current gen is a strange way to do things. Apple will also have a next gen M chip.
  - NathanOsullivan 6y ago
    AMD has a public roadmap, and (assuming they execute) their next CPU in 2021 will be 5nm. Apple do not of course, but TSMC have stated they expect 3nm to be produced in volume in 2H22 which tells us we have at least one more round of Apple Silicon on 5nm. In 2021 we will presumably see Apple Silicon parts with increased core counts and desktop TDP This will be our first chance to see how the best of ARM goes against the best of X86 in like-for-like configurations.
- whynotminot 6y ago
  > I haven't studied it carefully, but it sure looks like 90% of the performance improvement is using a big cache, which is a totally obvious thing to do. Also the big x86 guys have more or less been asleep at the wheel for almost a decade. Dude, has Intel called you yet? You've got some serious CTO chops.
Zenst 6y ago
In some ways it is the environment the M1 was born from that helped. mobile space CPU's focus upon low power usage and that has seen many core software tasks get dedicated instructions and why you end up with the M1 in some tests utterly trouncing competition as it has dedicated hardware catering for the common niche things that software ends up doing - the hardware video encoding being a small area, but deep down, more than that. This along with advances in software/hardware integration and being able to synergies that at a level nobody else can. The way to think of it is - if Intel did an operating system from scratch, it would tap the CPU extremely well compared to others due to them knowing the internals better and fully. Then add the ability for them to see that adding some dedicated hardware to replace some software instruction combinations and you start to see a tightly integrated team of CPU and Operating system/software. One area that I've always wished CPU's would take would be a dedicated core or two for the OS that is completely isolated from the other cores, which would be for the software/applications you run. Now if those ran about two different architectures - darn that would be the inner geek in me appeased.
- africanboy 6y ago
  The project HydrOS aimed to build an Erlang operating system that way: one core for the OS, one scheduler per core other than the OS one. Unfortunately it looks the project is now abandoned
  - Zenst 6y ago
    Thank you, not heard of that, had a look https://www.youtube.com/watch?v=8OyRFbf6MDk https://www.youtube.com/watch?v=8OyRFbf6MDk Seems the main/only dev moved onto other things and it stagnated.
- stoat_meniscus 6y ago
  The PS3 did something like this. One processing unit of the Cell processor was reserved for the OS while the rest could be used for games.
- setpatchaddress 6y ago
  What would your goal be? I think locking a modern, general-purpose OS to a small number of cores would artificially constrain performance, assuming a reasonable scheduler.
xorcist 6y ago
> by the iPod without most experts believing Apple could make a mobile phone Except for all the people practically begging Apple to make a phone for years, except all the analysts who wrote essays on how computer companies could make successful phones, except for all the fanboys making fan-art of phones with that big circular wheel.
pmlnr 6y ago
Or... in 10 years, we'll have another round of Meltdown, Spectre, etc, because of the big tricks.
api 6y ago
I don't buy it. I think there is in fact one "trick," which is shedding the X86 decode bottleneck. People always make the point that the X86 decoder is only ~5% of the die. Sure, that's true, but keep two things in mind: (1) While it's only 5% of the die, it runs constantly at full utilization. The ALU is also only a small percentage of the die (5-10%). How hot does your CPU get when you're running the ALU full blast? Now consider that there is a roughly ALU-sized piece always running full blast no matter what the CPU is doing because X86 instructions are so complex to decode. Not only does this give X86 a higher power use "floor," but it means there's always more heat being dissipated. This extra heat limits thermal throttling and thus sustained clock speed unless you have really good cooling, which is why the super high performance X86 chips need beefy heatsinks or water cooling. (2) It apparently takes exponentially more silicon to decode X86 instructions with parallelism beyond 4 instructions at once. This limits instruction level parallelism unless you're willing to add heat dissipation and power, which is a show stopper for phones and laptops and undesirable even for servers and desktops. People make the point that ARM64 (and even RISC-V) are not really "RISC" in the classic "reduced" sense as they have a lot of instructions, but that's not really relevant. The complexity in X86 decoding does not come from the number of instructions or even the number of legacy modes and instructions but from the variable length of these instructions and the complexity of determining that length during pipelined decode. M1 leverages the ARM64 instruction set's relative decode simplicity to do 8X parallel decode and keep a really deep reorder buffer full, permitting a lot of reordering and instruction level parallelism for a very low cost in power and complexity. That's a huge win. Moreover there is nothing stopping them from going to 12X, 16X, 24X, and so on if it's profitable to do so. The second big win is probably weaker memory ordering requirements in multiprocessor ARM, which allows more reordering. There are other wins in M1 like shared memory between CPU, GPU, and I/O, but those are smaller wins compared to the big decoder win. So yes this does foreshadow the rise of RISC-V as RISC-V also has a simple-to-decode instruction set. It would be much easier to "pull an M1" with RISC-V than with X86. Apple could have gone RISC-V, but they already had a huge investment in ARM64 due to the iPhone and iPad. X86 isn't quite on its death bed, but it's been delivered a fatal prognosis. It'll be around for a long long time due to legacy demand but it won't be where the action is.
- imtringued 6y ago
ogre_codes 6y ago
> The sum of a large number of small engineering improvements, coupled with a lot of component integration detail work, Exactly. ARM has been progressing faster than Intel. For the past 8 years or so, Apple has had the fastest ARM CPU out there on the iPhone/ iPad. Apple has sucked up TSMC's 5nm production. They've integrated a pile of relevant coprocessors into the CPU and put fast RAM on the package. The SSD is lightning fast and SSD encryption is done via a dedicated coprocessor. It's not one magic trick, it is countless bits of engineering, manufacturing, and purchase choices.
jonas21 6y ago
> the near term lockup of the top of the line fab in the supply chain also reminds me of how Apple had secured exclusivity for some key leading edge iPhone parts (was it the screens?). Yes, Apple managed to lock up most of the global supply of capacitive touchscreens for about a year after the iPhone came out. The iPhone wasn't the first phone to use a capacitive touchscreen, but for a while, it seemed like it was because nobody else could produce devices with them in large volumes. People used to dismiss Tim Cook as "just" a supply chain guy. But I think it's become clear that supply chain management is at least as important to Apple's success as anything on the design or marketing side.

jolux 6y ago

The first A-series chip was the A4, because it came out with the iPhone 4.

alwillis 6y ago

So the M1 strikes me as the result of something that Apple has the ability to pull off from time to time. Perhaps you haven't been paying attention? Apple shipped 64-bit ARM processors for the iPhone at least a year before Qualcomm could do it for Android devices. The reaction to the A7 was similar to what we're seeing now with the M1—not possible, there's some trickery going on, etc. Apple is pretty good at this processor transition thing, going from 68k to PowerPC to Intel to ARM. And it more than makes up for some pretty spectacular tactical mis-steps (I’m looking at you, puck mouse, cube mac, butterfly keyboard). Except for the recent keyboard issues, you're literally talking about another era. I wouldn't put the shape of the mouse for the 1998 iMac in the same category as transitioning a $9 billion revenue product line to a radically different processor architecture.

dwighttk 6y ago
> not possible, there's some trickery going on “...and even if they did it, it doesn’t matter” (though I guess not many are saying that about M1)
- alwillis 6y ago
  Yes—there was a lot of “it won’t matter” talk when the A7 shipped.
hajile 6y ago
> Apple shipped 64-bit ARM processors for the iPhone at least a year before Qualcomm could do it for Android devices. The reaction to the A7 was similar to what we're seeing now with the M1—not possible, there's some trickery going on, etc. That is because it is not possible to ship a top-end design for a new ISA in that amount of time. The more reasonable answer is they had been working on a new core design for some years before. AMD has hinted that their Zen design makes it relatively easy to swap the x86 frontend for an ARM frontend. Apple was considering buying MIPS around that time. I suspect they strong-armed ARM into accepting their ARMv8 proposal because it was good and because Apple buying MIPS would be disastrous for ARM's share price. At that point, it wasn't faster than possible, it was just designing the last part of the chip (or if both frontends were being worked on in tandem, cancelling one of them and focusing everyone on the other). This explains why ARM announced v8 and then took the full 4 years to ship their first low-power core (A53) and even longer to ship their bad first try at a high-performance core (A57 -- with the more baked A72 being superior in almost every way).
DonHopkins 6y ago
Don't forget Apple's first transition from 6502 to 68k. That was pretty bumpy though.
- alwillis 6y ago
  I was only talking about the Mac, which never used the 6502–that was the Apple II. The Apple IIgs did end up on the 65816.

simonh 6y ago

Apple has used exclusive access to advanced hardware as a differentiator several times. With screens it was Retina. They funded the development and actually owned the manufacturing equipment and leased it to the manufacturing subcontractors. Also in 2008 they secured exclusive access to a then new laser cutting technology that they used to etch detail cuts in the unibody enclosures of their MacBooks, and then iPads. This enables them to mill and then precision cut the device bodies out of single blocks of Aluminium. They’ve also frequently bought small companies to secure exclusive use of their specialist tech, like Anobit for their flash memory controllers, Primesense for the face mapping tech in FaceID, and there are many more. For Apple simply having the best isn’t enough, they want to be the only people with the best.

FullyFunctional 6y ago
They bought Intrinsity as well, leaving us wonder about the fate of Fast14.
vizzier 6y ago
I believe this is the only consumer 5nm chip currently available as well. Ryzen gen 3 is still on 7nm. I'd be interested to see how well general purpose compute on the m1 vs ryzen gen 3 mobile will be.
- leecb 6y ago
  The Huawei Mate 40 came out two months ago, and uses the Hisilicon Kirin 9000, which is also on TSMC's 5nm. It has about 30% more transistors and a higher clockspeed than the A14.
  - AsyncAwait 6y ago
    AMD has substantially more CPU/Microarch design experience.
  - 1123581321 6y ago
    Would you say that the comparison to the A13 from this article is fair? https://www.notebookcheck.net/HiSilicon-Kirin-9000-Processor-Benchmarks-and-Specs.505389.0.html https://www.notebookcheck.net/HiSilicon-Kirin-9000-Processor...

_ph_ 6y ago

The sum of a large number of small engineering improvements, coupled with a lot of component integration detail work, topped off by some very shrewd supply chain arrangements. I think you precisely have it. There is no single magic reason the M1 is so good, just a lot of things coming together. They start with a better instruction set than x86, have of course the best process available, and perhaps the largest part, they have built up an increadible team over a decade. And they are extremely focussed in what they target. If anything, that is Apples "magic". They are not making a chip which is built in an abstract manner to be sold to random customers. They have exactly their needs in mind and execute towards those. In a sense AMD did that with the chips for the Playstation/XBox. Like the M1 it is basically a SOC. There optimized for great graphics performance. Unfortunately, those chips are not sold separately for building your own PC.

deleted 6y ago

[deleted]

gchadwick 6y ago

> The sum of a large number of small engineering improvements, coupled with a lot of component integration detail work, topped off by some very shrewd supply chain arrangements. I think the vertical integration they have is a major advantage too. I used to work at arm on CPUs. One thing I worked on was memory prefetching which is critical to performance. When designing a prefetcher you can do a better job if you have some understanding or guarantees as to the behaviour of the wider memory system (better yet if you can add prefetching specific functionality to it). The issue I faced is the partners (Samsung, Qualcomm etc) are the ones implementing the SoC and hence controlling the wider memory system. They don't give you detailed specs of how that works, nor is there an method where you can discuss with them appropriate ways to build things to enable better prefetching performance. You end up building something that's hopefully adaptable for multiple scenarios and no one ever gets a chance to do some decent end to end performance tuning. I'm either working with a model of what the memory system might be and Qualcomm/Samsung etc engineers are working with the CPU as a black box trying to tune their side of things to work better. Were we all under one roof I suspect we could easily have got more out of it. You also get requirements based upon targets to hit for some specific IP, rather than requirements around the final product, e.g. silicon area. Generally arm will be keen to keep area increase low or improve performance / area ratio without any huge shocks on overall area. If you're apple you just care about the final end user experience and the potential profit margin. You can run the numbers and realise you can go big on silicon area and get where you want to be. With a multi-company/vendor chain each link is trying to optimise for some number they control, even if that overal has a negative impact on the final product.

fluffy87 6y ago
Nvidia makes arm processors, GPUs and SoCs, so this integration will be good for them if the arm sale is approved.
socialdemocrat 6y ago
Very interesting comment. I mean you see some of the same things with companies like Tesla also pushing vertical integration. A lot of the examples you see are similar to what you talk about. You can cut down on the friction between different parts. I remember an example of software controlling a blinking icon on the dashboard, where this was a 10 minute code change for Tesla but a 2-3 month update cycle for a traditional automaker due to the dashboard hardware coming from a supplier.

scottlocklin 6y ago

I haven't studied it carefully, but it sure looks like 90% of the performance improvement is using a big cache, which is a totally obvious thing to do. Also the big x86 guys have more or less been asleep at the wheel for almost a decade. My go to example: my 2011 x220 sandybridge stinkpad is faster than my 2017 kaby lake mbp. 2005 machines (I dunno, Lakeport?) aren't even in the same ballpark as modern machines. Had that pace continued up to current year, the M1 chip would be a stinker. As it is, AMD is close and could smoke M1 in next generation 5nm chips, restoring order to the universe.

CrazyStat 6y ago
>As it is, AMD is close and could smoke M1 in next generation 5nm chips, restoring order to the universe. Comparing next gen to current gen is a strange way to do things. Apple will also have a next gen M chip.
- NathanOsullivan 6y ago
  AMD has a public roadmap, and (assuming they execute) their next CPU in 2021 will be 5nm. Apple do not of course, but TSMC have stated they expect 3nm to be produced in volume in 2H22 which tells us we have at least one more round of Apple Silicon on 5nm. In 2021 we will presumably see Apple Silicon parts with increased core counts and desktop TDP This will be our first chance to see how the best of ARM goes against the best of X86 in like-for-like configurations.
whynotminot 6y ago
> I haven't studied it carefully, but it sure looks like 90% of the performance improvement is using a big cache, which is a totally obvious thing to do. Also the big x86 guys have more or less been asleep at the wheel for almost a decade. Dude, has Intel called you yet? You've got some serious CTO chops.

Zenst 6y ago

In some ways it is the environment the M1 was born from that helped. mobile space CPU's focus upon low power usage and that has seen many core software tasks get dedicated instructions and why you end up with the M1 in some tests utterly trouncing competition as it has dedicated hardware catering for the common niche things that software ends up doing - the hardware video encoding being a small area, but deep down, more than that. This along with advances in software/hardware integration and being able to synergies that at a level nobody else can. The way to think of it is - if Intel did an operating system from scratch, it would tap the CPU extremely well compared to others due to them knowing the internals better and fully. Then add the ability for them to see that adding some dedicated hardware to replace some software instruction combinations and you start to see a tightly integrated team of CPU and Operating system/software. One area that I've always wished CPU's would take would be a dedicated core or two for the OS that is completely isolated from the other cores, which would be for the software/applications you run. Now if those ran about two different architectures - darn that would be the inner geek in me appeased.

africanboy 6y ago
The project HydrOS aimed to build an Erlang operating system that way: one core for the OS, one scheduler per core other than the OS one. Unfortunately it looks the project is now abandoned
- Zenst 6y ago
  Thank you, not heard of that, had a look https://www.youtube.com/watch?v=8OyRFbf6MDk https://www.youtube.com/watch?v=8OyRFbf6MDk Seems the main/only dev moved onto other things and it stagnated.
stoat_meniscus 6y ago
The PS3 did something like this. One processing unit of the Cell processor was reserved for the OS while the rest could be used for games.
setpatchaddress 6y ago
What would your goal be? I think locking a modern, general-purpose OS to a small number of cores would artificially constrain performance, assuming a reasonable scheduler.

xorcist 6y ago

> by the iPod without most experts believing Apple could make a mobile phone Except for all the people practically begging Apple to make a phone for years, except all the analysts who wrote essays on how computer companies could make successful phones, except for all the fanboys making fan-art of phones with that big circular wheel.

pmlnr 6y ago

Or... in 10 years, we'll have another round of Meltdown, Spectre, etc, because of the big tricks.

api 6y ago

I don't buy it. I think there is in fact one "trick," which is shedding the X86 decode bottleneck. People always make the point that the X86 decoder is only ~5% of the die. Sure, that's true, but keep two things in mind: (1) While it's only 5% of the die, it runs constantly at full utilization. The ALU is also only a small percentage of the die (5-10%). How hot does your CPU get when you're running the ALU full blast? Now consider that there is a roughly ALU-sized piece always running full blast no matter what the CPU is doing because X86 instructions are so complex to decode. Not only does this give X86 a higher power use "floor," but it means there's always more heat being dissipated. This extra heat limits thermal throttling and thus sustained clock speed unless you have really good cooling, which is why the super high performance X86 chips need beefy heatsinks or water cooling. (2) It apparently takes exponentially more silicon to decode X86 instructions with parallelism beyond 4 instructions at once. This limits instruction level parallelism unless you're willing to add heat dissipation and power, which is a show stopper for phones and laptops and undesirable even for servers and desktops. People make the point that ARM64 (and even RISC-V) are not really "RISC" in the classic "reduced" sense as they have a lot of instructions, but that's not really relevant. The complexity in X86 decoding does not come from the number of instructions or even the number of legacy modes and instructions but from the variable length of these instructions and the complexity of determining that length during pipelined decode. M1 leverages the ARM64 instruction set's relative decode simplicity to do 8X parallel decode and keep a really deep reorder buffer full, permitting a lot of reordering and instruction level parallelism for a very low cost in power and complexity. That's a huge win. Moreover there is nothing stopping them from going to 12X, 16X, 24X, and so on if it's profitable to do so. The second big win is probably weaker memory ordering requirements in multiprocessor ARM, which allows more reordering. There are other wins in M1 like shared memory between CPU, GPU, and I/O, but those are smaller wins compared to the big decoder win. So yes this does foreshadow the rise of RISC-V as RISC-V also has a simple-to-decode instruction set. It would be much easier to "pull an M1" with RISC-V than with X86. Apple could have gone RISC-V, but they already had a huge investment in ARM64 due to the iPhone and iPad. X86 isn't quite on its death bed, but it's been delivered a fatal prognosis. It'll be around for a long long time due to legacy demand but it won't be where the action is.

imtringued 6y ago

ogre_codes 6y ago

> The sum of a large number of small engineering improvements, coupled with a lot of component integration detail work, Exactly. ARM has been progressing faster than Intel. For the past 8 years or so, Apple has had the fastest ARM CPU out there on the iPhone/ iPad. Apple has sucked up TSMC's 5nm production. They've integrated a pile of relevant coprocessors into the CPU and put fast RAM on the package. The SSD is lightning fast and SSD encryption is done via a dedicated coprocessor. It's not one magic trick, it is countless bits of engineering, manufacturing, and purchase choices.

jonas21 6y ago

> the near term lockup of the top of the line fab in the supply chain also reminds me of how Apple had secured exclusivity for some key leading edge iPhone parts (was it the screens?). Yes, Apple managed to lock up most of the global supply of capacitive touchscreens for about a year after the iPhone came out. The iPhone wasn't the first phone to use a capacitive touchscreen, but for a while, it seemed like it was because nobody else could produce devices with them in large volumes. People used to dismiss Tim Cook as "just" a supply chain guy. But I think it's become clear that supply chain management is at least as important to Apple's success as anything on the design or marketing side.