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Ask HN: Can competitors catch up to Apple Silicon?

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201–210 of 323 posts

Re: Ask HN: Can competitors catch up to Apple Silicon?

#201
post #148

Earlier quoted context omitted.

But ARM didn't start out as a shitpile of attempted backwards compatibility with an 8 bit CPU. The i8086 was made as an evolution of the i8080.

And it's also not really "nearly as old" considering how fast stuff developed in the early day - the first ARM CPUs launched in 1986, and the i8086 in 1978 - 8 years earlier.

That still doesn’t make ARM “modern”.

Re: Ask HN: Can competitors catch up to Apple Silicon?

#202

Earlier quoted context omitted.

Oh so the M2 is a lot slower than Samsung phones? Samsung Galaxy S20 FE 5G = 2147483647 multi-core score https://browser.geekbench.com/v5/cpu/15129294 But only 8928 multi-core for the new M2. Or maybe that page is kinda unreliable?

Regardless of how fast the phone is, it’s gonna throttle way down under any heavy load, unless you keep it super cool.

They probably dipped it in liquid nitrogen during testing ;)

Re: Ask HN: Can competitors catch up to Apple Silicon?

#203
post #23

The picture you're painting is far too simple. There are many metrics that play a role for different applications. A modern Nvidia card is magnitudes faster than any CPU and the M1 GPUs. A Nvidia A100 card has HBM memory with ~2TB/s bandwidth. On the other hand, there are areas where a ~5GHz intel CPU is competitive, or even older server chips with AVX can compete. So let's see what happens when Intel and AMD step to…

Both Intel and AMD have the major disadvantage of having (or, let's say, wanting) to maintain x86 backward compatibility - which means not only staying compatible with the almost 45 year old CISC instruction set of the Intel 8086, but also with the whole line of CPUs that came after it. All this ballast makes it harder for them to build an energy-efficient CPU. By contrast, Apple was able to just create a new CPU bas…

But you can run x86 software on the M1 at almost native speed through a software translator. Isn't that proof enough that the instruction set itself isn't what's holding back the hardware?

Re: Ask HN: Can competitors catch up to Apple Silicon?

#204
The GPU is not that fast. It is at heart a mobile architecture that excels when the application takes that into account. Otherwise, it is mediocre. It is also worth noting that performance does not scale linearly with power. You can often get something like 75% of the performance at 50% of the power.

Re: Ask HN: Can competitors catch up to Apple Silicon?

#205

And then you try gaming and it is comparable to a Ryzen 7 4800H (45W)/ Nvidia GTX 1650ti (50W).

Several versions of M1 and M2 GPU’s but M1 8-Core GPU (15W) being roughly equivalent to low end 50W GPU’s makes me want to see what Apple could do with a discrete graphics card.

10+ times M2 performance as a discrete 200W card with dedicated memory and 100ish cores could be really compelling depending on the price point. That’s RTX 3090 territory, but much easier to cool etc.

Re: Ask HN: Can competitors catch up to Apple Silicon?

#206

Earlier quoted context omitted.

"even CUDA can be replaced without much disruption in most cases" Tell that to AMD who's been missing out on the very lucrative government data-center market because they can't replace CUDA well enough. BTW, PyTorch and TensorFlow still ship without AMD support despite AMD's ROCm being around for 6 years now.

Is that more an indictment of ROCm immaturity or of PyTorch/TensorFlow unwillingness to support it?

I believe ROCm isn't usable yet.

I don't know anyone who successfully trained a state of the art neural network on anything that was not NVIDIA. AMD keeps offering their own forks of PyTorch and TensorFlow, but last time I checked they were years outdated, and nobody uses them. So either PyTorch/TensorFlow are secretly sponsored by NVIDIA, or AMD's and Apple's CUDA replacements aren't mature enough yet. Given how many bugs there still are in CUDA despite them being around for a long time,

I'd guess that building a GPU-capable BLAS library is just a lot more work than one would think. I mean I also always wonder why CUDA comes with 400 MB of GPU shaders ... but apparently they need that to cover every edge case in a fast way.

FYI, this is the ROCm "getting started" guide: https://github.com/RadeonOpenCompute/ROCm-docker/blob/master...

NVIDIA has a GUI installer for CUDA.

Re: Ask HN: Can competitors catch up to Apple Silicon?

#207
post #138

Earlier quoted context omitted.

Classic ARM mode has been removed. Only ARMv8 is supported now.

The existence of 8086 instructions doesn’t slow AMD64 instructions.

It kinda does make the critical path in the decoder slower.

Re: Ask HN: Can competitors catch up to Apple Silicon?

#208

Earlier quoted context omitted.

But doesn’t your statement prove that there are decisions and things the user of a node can make which effect the end result? Therefore, is not just process node that matters.

Obviously you can choose not to aim for the best possible performance in order to reduce costs. But for the companies that are competing for the absolute best performance at any cost, which doesn't include Qualcomm, by far the biggest factor determining that performance is the fabrication technology.

That’s an interesting take given this thread because Apple has explicitly stated they don’t prioritize performance, they prioritize performance per watt, which is not the same thing. And that also shows there’s a whole design space here and just focusing on one dimension, process node, is overly simplistic.

Re: Ask HN: Can competitors catch up to Apple Silicon?

#209
post #78
post #23

Earlier quoted context omitted.

Both Intel and AMD have the major disadvantage of having (or, let's say, wanting) to maintain x86 backward compatibility - which means not only staying compatible with the almost 45 year old CISC instruction set of the Intel 8086, but also with the whole line of CPUs that came after it. All this ballast makes it harder for them to build an energy-efficient CPU. By contrast, Apple was able to just create a new CPU bas…

Do we know whether that x86 backward compatibility is all that problematic? If I’m not mistaken, it is only used as a “public API” even in current CPUs, and on a microcode level it doesn’t have as much relevance.

Backwards compatibility costs a tremendous amount of silicon to handle the micro-decoding. The more problematic aspect is things like the segment registers from 16-bit x86, which can give you a 4-operand LEA, and other such nonsense. Sure, these operands can be microcoded, but that leaves a lot of performance on the table when a modern program wants to use an old instruction (SETcc comes to mind for branch elimination).

Re: Ask HN: Can competitors catch up to Apple Silicon?

#210
post #158

Earlier quoted context omitted.

For example: Decode. One of the things Apple CPUs keep being praised for is how wide they are. To be wide effectively and keep your execution units busy, you need a wide decoder. With aarch64 it is easy. Every instruction is 4 bytes on a 4 byte boundary. Want a 4-wide decoder? Ingest 16 bytes and copy-and-paste the same decoder 4 times. X86 instructions are variable-length: 1-15 bytes. And you do not know how long an…

And those bytes matter when most Intel CPU cores have only a few dozen KB of L1I cache. Interestingly, the M1 and M2 performance cores have a whopping 192KB of L1 instruction cache.

ARM instructions aren't as compact as their x86 counterparts, so they need a big cache to get similar performance on cache-bound applications.
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