Apple's "unified memory" marketing is so strong that even tech literate people seem to have this misconception!

They have managed to pull this sort of thing off many many times. https://en.wikipedia.org/wiki/Reality_distortion_field

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Rohansi 3 hours ago | parent | next [-]

Yup, the only reason Macs have higher memory bandwidth is because they use more memory channels, which gives them a wider bus. Both Intel and AMD only allow more than dual channel memory on server class processors these days.

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kstrauser 3 hours ago | parent | next [-]

The “Apple only does X better because they do Y” thing has been a meme for ages. I remember dismissals like “PowerPC is only faster at math because it has more integer units” or something along those lines, and thinking, uh, isn’t that a good thing?

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pdpi 2 hours ago | parent | next [-]

There's a qualitative difference between "they're doing a different thing" and "they're doing the same thing, tuned differently". GP is saying that this is a case of "they just tuned it differently".

This distinction doesn't change what the performance numbers look like today, but it does inform what changes would be necessary for those numbers to look different tomorrow. E.g. Apple Silicon isn't fundamentally orders of magnitude more efficient than x86, they just used smaller features. Newer Intel and AMD chips made on equivalent processes _also_ get similar efficiency gains.

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pixl97 3 hours ago | parent | prev | next [-]

Depends on the expense trade off.

If I get 10% more performance for 50% more cost it really depends on one's needs, for example.

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Rohansi 3 hours ago | parent | prev [-]

I am just saying it's not magic and x86 is capable of doing the same. Quad channel memory used to be more common in consumer hardware but now it looks like you don't even have the option anymore for desktops. AMD's Strix Halo was the first sign to reversing that (it has quad channel memory!) and hopefully we see more of that in the future.

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colejohnson66 2 hours ago | parent [-]

AMD does market segmentation and limits consumer chips to dual-channel. You need to cough up the dough and get Threadripper for quad-channel. Or even more for Threadripper Pro to get octa-channel.

	▲	torginus an hour ago \| parent \| next [-]
		Afaik steam deck is quad channel, despite it being a pretty low end chip (with a decent GPU though)
	▲	Rohansi 2 hours ago \| parent \| prev [-]
		As I mentioned above AMD's Strix Halo has quad channel memory and is consumer level. But yes, other than that everything is segmented away.

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Kon5ole 3 hours ago | parent | prev | next [-]

The memory bandwidth is a small thing compared to the massive win you get by not having to move data between two memory pools at all.

	▲	fooker 2 hours ago \| parent \| next [-]
		Often you don't move memory around as a programmer, but that's exactly what happens in the background. It's the address space that's unified, not always the physical hardware. The data movement (when needed) is handled transparently in the background by page faults and other tricks.
	▲	Rohansi 3 hours ago \| parent \| prev [-]
		Depends on your workload. And AMD has supported unified memory long before Apple Silicon existed anyway.

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throwaway85825 an hour ago | parent | prev [-]

Except strix halo.

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Kon5ole 3 hours ago | parent | prev [-]

Having unified memory is a real advantage though, it's not a reality distortion.

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davrosthedalek 3 hours ago | parent | next [-]

The price is that you essentially glue CPU and GPU together, which limits total compute, from a size and thermal perspective.

This is really not a limit because of unified memory -- in principle, PCIe GPUs could read/write main memory without the CPU. But it's a limit for /fast/ unified memory, because fast means close.

So unified memory is great as long as the integrated GPU is strong enough. Then it has two advantages: a) probably faster transfer CPU<->GPU (but that's an implementation choice for the non-unified case b) If you either need a lot of memory for the CPU or the GPU, but not for both at the same time, you pay for memory only once.

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nvme0n1p1 3 hours ago | parent | prev | next [-]

Agreed. That's why it's a good thing all computers made in the past 15 years have unified memory, not just macs.

https://x.com/Lina_Hoshino/status/1820947147312820497

	▲	Kon5ole 31 minutes ago \| parent \| next [-]
		In theory perhaps but the benefit is not as relevant with a weak iGPU. In practice all PC's with performance ambitions had a dGPU until Strix Halo and Panther Lake.
	▲	stymaar 2 hours ago \| parent \| prev [-]
		Is that Marcan's vtuber persona (Asahi Lina) that changed name since Marcan doesn't work on Asahi Linux anymore?

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fooker 3 hours ago | parent | prev [-]

It is a real advantage.

The reality distortion is that people seem to believe it's HBM, or somehow it gives you extraordinary amounts of vram. Neither are really true.