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Ask HN: How did Apple manage to create such a better chip than Intel?

news.ycombinator.com

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Re: Ask HN: How did Apple manage to create such a better chip than Intel?

#11

Post by kortex »

https://news.ycombinator.com/item?id=25257932

My 10,000' view understanding:

- Small feature size. M1 is a 5nm process. Intel is struggling to catch up to TSMC's 7nm process

- more efficient transistors. 7nm uses finFet. M1 probably uses GAAFET, which means you can cram more active gate volume in less chip footprint. This means less heat and more speed

- layout. M1 is optimized for Apple's use case. General purpose chips do more things, so they need more real estate

- specialization. M1 offloads oodles of compute to hardware accelerators. No idea how their code interfaces with it, but I know lots of the demos involve easy-to-accellerate tasks like codecs and neural networks

- M1 has tons of cache, IIRC, something like 3x the typical amount

- some fancy stuff that allows them to really optimize the reorder buffer, decoder, and branch prediction, which also leverages all that cache

Re: Ask HN: How did Apple manage to create such a better chip than Intel?

#12

Post by throwarchitect »

wpg_steve wrote: post #6

I read that the out of order execution of the RISC was simpler to handle with the fixed 32 bit instructions. They said Apple managed to dispatch 8 instructions in parallel whereas the hi end CISC (x86) tops out at 4.

The greater simplicity of ARMv8 and its fixed sized instructions definitely helps, but also Intel runs their cores at nearly 2x higher frequency, which means a lot less logic can be squeezed into a clock cycle. That makes it much harder to to make a wider processor.

Re: Ask HN: How did Apple manage to create such a better chip than Intel?

#14

Post by gruez »

kortex wrote: post #11

https://news.ycombinator.com/item?id=25257932 My 10,000' view understanding: - Small feature size. M1 is a 5nm process. Intel is struggling to catch up to TSMC's 7nm process - more efficient transistors. 7nm uses finFet. M1 probably uses GAAFET, which means you can cram more active gate volume in less chip footprint. This means less heat and more speed - layout. M1 is optimized for Apple's use case. General purpose c…

>- specialization. M1 offloads oodles of compute to hardware accelerators. No idea how their code interfaces with it, but I know lots of the demos involve easy-to-accellerate tasks like codecs and neural networks

that wouldn't help in benchmarks, would it? Only in the most dishonest benchmarks would they compare x264 to a hardware h.264 encoder, for instance.

Re: Ask HN: How did Apple manage to create such a better chip than Intel?

#15

Post by redisman »

ibraheemdev wrote: post #7

I just wanted to point out that it is not Apple out of the blue made a chip better than Intel's. They have also been designing chips for quite a while. The APL0098 chip that was used in the original iPhone was introduced back in 2007.

Right the M1 is based on A14 - the iPhone/iPad chip. It’s just the first PC one based on that architecture. Making top of the line mobile chips has given them a huge efficiency leg up. The SoC also gives big gains compared to a traditional separation of memory modules and CPUs

Re: Ask HN: How did Apple manage to create such a better chip than Intel?

#16

Post by chubot »

I imagine part of it is vertical integration. If you make the hardware that the CPU integrates with, and the OS that runs on the hardware, you can do a lot of optimization.

Intel CPUs don't know what memory they're talking to, i.e. they have to support a variety of memory. Likewise they don't necessarily know what OS they're running; how it context switches, etc. If it's virtualized, etc. Sure they have optimizations for those common cases, but the design is sort of accreted rather than derived from first principles.

To make an analogy, if you know your JS is running on v8, you can do a bunch of optimization so you don't fall off the cliff of the JIT, and get say 10x performance wins in many cases. But if you're writing JS abstractly then you may use different patterns that hit slow paths in different VMs. Performance is a leaky abstraction.

Re: Ask HN: How did Apple manage to create such a better chip than Intel?

#18

Post by titzer »

Lots of other comments point out the vertical integration.

For raw single-thread performance:

1. ARM64 is a fixed-width instruction set, so their frontend can decode more instructions in parallel.

2. They got one honking monster of an out-of-order execution engine. (630 entries), which feed:

3. 16 execution ports.

Re: Ask HN: How did Apple manage to create such a better chip than Intel?

#19

Post by flumpcakes »

gruez wrote: post #14
kortex wrote: post #11

https://news.ycombinator.com/item?id=25257932 My 10,000' view understanding: - Small feature size. M1 is a 5nm process. Intel is struggling to catch up to TSMC's 7nm process - more efficient transistors. 7nm uses finFet. M1 probably uses GAAFET, which means you can cram more active gate volume in less chip footprint. This means less heat and more speed - layout. M1 is optimized for Apple's use case. General purpose c…

>- specialization. M1 offloads oodles of compute to hardware accelerators. No idea how their code interfaces with it, but I know lots of the demos involve easy-to-accellerate tasks like codecs and neural networks that wouldn't help in benchmarks, would it? Only in the most dishonest benchmarks would they compare x264 to a hardware h.264 encoder, for instance.

Maybe - but how do you know they are off loading to a hardware encoder?

Example: I run a benchmark for AES encryption - a modern CPU will have circuitry designed explicitly for this task and it's asm instructions. An old CPU just supporting the base x86 instructions probably doesn't have a hardware solution. Is it unfair to compare them?

If the utilisation of the hardware accelerators is completly opaque to the user (not importing special libraries) is it unfair that one CPU has specific hardware implementation for common tasks and one only has the generic circuitry?

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