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283 points walterbell | 52 comments | | HN request time: 0.273s | source | bottom
1. darkamaul ◴[] No.45769289[source]
Better (or simply more) ARM processors, no matter who makes them, are a win. They tend to be far more power-efficient, and with performance-per-watt improving each generation, pushing for wider ARM adoption is a practical step toward lowering overall energy consumption.
replies(5): >>45769421 #>>45769508 #>>45769815 #>>45769973 #>>45772372 #
2. coffeebeqn ◴[] No.45769421[source]
How is running desktop Linux on these?
replies(2): >>45769471 #>>45772886 #
3. hmlwilliams ◴[] No.45769471[source]
I run desktop linux via postmarketOS on a Lenovo Duet 5 (Snapdragon 7c). It isn't the most powerful device and the webcam doesn't work but other than that it works well and battery life is excellent
replies(1): >>45770454 #
4. ahoka ◴[] No.45769508[source]
Are ARM processors inherently power efficient? I doubt.

Performance per watt is increasing due to the lithography.

Also, Devon’s paradox.

replies(5): >>45769580 #>>45770046 #>>45770800 #>>45773990 #>>45779586 #
5. ggm ◴[] No.45769580[source]
Aside from lithography there's clever design. I don't think you can quantify that but it's not nothing.
replies(1): >>45770093 #
6. pjmlp ◴[] No.45769815[source]
With the caveat that ARM isn't a industry standard like PC has become, thus while propritary OSes can thrive, FOSS has a much higher challenge other than OEM specific distros or downstream forks.

Stuff like this, https://www.amazon.de/-/en/Microsoft-Corporation/dp/15723171...

replies(2): >>45770548 #>>45780610 #
7. high_na_euv ◴[] No.45769973[source]
ISA is not that relevant, it is all about what you want to achieve with your CPU
replies(1): >>45770731 #
8. jorvi ◴[] No.45770046[source]
They aren't inherently power efficient because of technical reasons, but because of design culture reasons.

Traditionally x86 has been built powerful and power hungry and then designers scaled the chips down whereas it's the opposite for ARM.

For whatever reason, this also makes it possible to get much bigger YoY performance gains in ARM. The Apple M4 is a mature design[0] and yet a year later the M5 is CPU +15% GPU +30% memory bandwidth +28%.

The Snapdragon Elite X series is showing a similar trajectory.

So Jim Keller ended up being wrong that ISA doesn't matter. Its just that it's the people in the ISA that matter, not the silicon.

[0] its design traces all the way back to the A12 from 2018, and in some fundamental ways even to the A10 from 2016.

replies(5): >>45770152 #>>45770164 #>>45771322 #>>45771561 #>>45780873 #
9. eb0la ◴[] No.45770093{3}[source]
Actually power efficiency was a side effect of having a straightforward design in the first ARM processor. The BBC needed a cheap (but powerful) processor for the Acort computer and a RISC chip was When ARM started testing their processor, they found out it draw very little power...

... the rest is history.

replies(2): >>45770718 #>>45772122 #
10. IshKebab ◴[] No.45770152{3}[source]
Do you have any actual evidence for that? Intel does care about power efficiency - they've been making mobile CPUs for decades. And I don't think they are lacking intelligent chip designers.

I would need some strong evidence to make me think it isn't the ISA that makes the difference.

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11. high_na_euv ◴[] No.45770164{3}[source]
As far as I know people aren't part of ISA :)
replies(1): >>45772991 #
12. high_na_euv ◴[] No.45770173{4}[source]
Isn't Lunar Lake first mobile chip with focus on energy eff? And it is reasonably efficient

We will see how big improvement is it's successor panther lake in January on 18A node

>I would need some strong evidence to make me think it isn't the ISA that makes the difference.

It is like saying that Java syntax is faster than C# syntax.

Everything is about the implementation: compiler, jit, runtime, stdlib, etc

If you spent decades of effort on peformance and ghz then don't be shocked that someone who spent decades on energy eff is better in that category

replies(3): >>45770819 #>>45770823 #>>45772691 #
13. fransje26 ◴[] No.45770454{3}[source]
> the webcam doesn't work

But.. ..why? Of all things, I would have expected the webcam to not be cpu-related..

replies(1): >>45770547 #
14. jorvi ◴[] No.45770460{4}[source]
https://chipsandcheese.com/p/arm-or-x86-isa-doesnt-matter

Basically, x86 uses op caches and micro ops which reduces instruction decoder use, the decoder itself doesn't use significant power, and ARM also uses op caches and micro ops to improve performance. So there is little effective difference. Micro ops and branch prediction is where the big wins are and both ISAs use them extensively.

If the hardware is equal and the designers are equally skilled, yet one ISA consistently pulls ahead, that leads to the likely conclusion that the way the chips get designed must be different for teams using the winning ISA.

For what it's worth, the same is happening in GPU land. Infamously, the M1 Ultra GPU at 120W equals the performance of the RTX 3090 at 320W (!).

That same M1 also smoked an Intel i9.

replies(2): >>45771281 #>>45771720 #
15. avhception ◴[] No.45770547{4}[source]
IIRC, it's because the ARM designs tend to use camera modules that come from smartphone-land.

Cameras used on x86-64 usually just work using that usb webcam standard driver (what is that called again? uvcvideo?). But these smartphone-land cameras don't adhere to that standard, they probably don't connect using USB. They are designed to be used with the SoC vendor's downstream fork of Android or whatever, using proprietary blobs.

replies(2): >>45771062 #>>45772735 #
16. antonkochubey ◴[] No.45770548[source]
There are the Arm SystemReady and ServerReady requirements/specifications that enable generic board support by the OSes.
replies(1): >>45770616 #
17. pjmlp ◴[] No.45770616{3}[source]
Thanks, I thought we were still on device trees and little else.
replies(1): >>45771792 #
18. delaminator ◴[] No.45770718{4}[source]
The BBC Micro had a 6502
19. usrusr ◴[] No.45770731[source]
For a CPU vendor, ISA is very relevant: most buyers will start their buying decision with ISA choice already fixed, and a vendor who can't offer a CPU with that ISA simply isn't in the race.

It does not matter whether you are a believer in horses for courses when it comes to ISA, or a believer in "frontend ISA does not matter because it's all translated away anyways": when buyers don't want what you have, you are out. And buyers are more like a stampeding herd than like rational actors when it comes to ISA choice. I'd see offering CPU for multiple ISA as an important hedge against the herd changing direction.

replies(1): >>45770989 #
20. iberator ◴[] No.45770800[source]
Yes they are. RISC philosophy apart from instruction set is also low gate count (so less energy used).

Nvidia can design super clean solution fron scratch - i can bet 50$ that its gonna be more efficient in MIPS/watt

replies(1): >>45771007 #
21. cogman10 ◴[] No.45770819{5}[source]
> Isn't Lunar Lake first mobile chip with focus on energy eff?

Not by a long shot.

Over a decade ago, one of my college professors was an ex-intel engineer who worked on Intel's mobile chips. He was even involved in an Intel ARM chip that ultimately never launched (At least I think it never launched. It's been over a decade :D).

The old conroe processors were based on Intel's mobile chips (Yonah). Netburst didn't focus on power efficiency explicitly so and that drove Intel into a corner.

Power efficiency is core to CPU design and always has been. It's easy create a chip that consumes 300W idle. The question is really how far that efficiency is driven. And that may be your point. Lunar Lake certainly looks like Intel deciding to really put a lot of resource on improving power efficiency. But it's not the first time they did that. The Intel Atom is another decades long series which was specifically created with power in mind (the N150 is the current iteration of it).

22. mrsmrtss ◴[] No.45770823{5}[source]
Actually, if you had made an opposite example, it might have gone against your point. ;) C# gives you a lot more control over memory and other low-level aspects, after all.
replies(2): >>45770980 #>>45771930 #
23. high_na_euv ◴[] No.45770980{6}[source]
Yet how much perf in recent dot nets comes from that, and how much comes from "Span<T>"ning whole BCL?
replies(1): >>45771187 #
24. high_na_euv ◴[] No.45770989{3}[source]
The context is: ISA's peformance and efficiency characteristics
replies(1): >>45775827 #
25. bluGill ◴[] No.45771007{3}[source]
Most of the gates on a cpu are not instruction decoding.
26. viraptor ◴[] No.45771062{5}[source]
A similar thing is happening in Intel land recently, where the cameras use ipu6 / ipu7 chips rather than dumping simple frames over USB. But this way we get a higher resolution / quality at least.
27. mrsmrtss ◴[] No.45771187{7}[source]
There’s much more to it than just Span<T>. Take a look at the performance improvements in .NET 10: https://devblogs.microsoft.com/dotnet/performance-improvemen.... When it comes to syntax, even something like structs (value types) can be a decisive factor in certain scenarios. C# is fast and with some effort, it can be very fast! Check out the benchmarks here: https://benchmarksgame-team.pages.debian.net/benchmarksgame/...
replies(1): >>45771419 #
28. IshKebab ◴[] No.45771281{5}[source]
ARM doesn't use micro-ops in the same way as x86 does at all. And that's not the only difference, e.g. x86 has TSO.

I'm not saying the skill of the design team makes zero difference, but it's ludicrous to say that the ISA makes no difference at all.

The claims about the M1 Ultra appear to be marketing nonsense:

https://www.reddit.com/r/MachineLearning/comments/tbj4lf/d_a...

29. znpy ◴[] No.45771322{3}[source]
You’re conveniently skipping the part where x86 can run software from 40 years ago but arm can drop entire instruction sets no problem (eg: jazelle).

Had been arm so weighted by backwards compatibility i doubt it would be so good as it is.

I really think intel/amd should draw a line somewhere around late 2000 and drop compatibility with stuff that slow down their processors.

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30. high_na_euv ◴[] No.45771419{8}[source]
I know that C# is fast, this is my favourite lang, but it is hard to say honestly which one is faster

I love the saying "i dont trust benchmarks that i didn't fake myself"

31. le-mark ◴[] No.45771540{4}[source]
> jazelle

That’s a blast from the past; native Java bytecode! Did anyone actually use that? Some J2ME phones maybe? Is there a more relevant example?

replies(1): >>45781279 #
32. ◴[] No.45771561{3}[source]
33. lossolo ◴[] No.45771720{5}[source]
> Infamously, the M1 Ultra GPU at 120W equals the performance of the RTX 3090 at 320W

That's not true.

34. jakogut ◴[] No.45771792{4}[source]
Practically speaking, very few systems actually support SystemReady. There's an experimental port of edk2 for the Raspberry Pi, but some hardware is unavailable when using it.
replies(1): >>45772750 #
35. layer8 ◴[] No.45771930{6}[source]
That’s semantics though, not syntax. What’s holding Java performance back in some areas is its semantics.

It might be the same with x86 and power-efficiency (semantics being the issue), but there doesn’t seem to be a consensus on that.

36. iainmerrick ◴[] No.45772122{4}[source]
You're getting your history mixed up.

Acorn won the bid to make the original BBC home computer, with a 6502-based design.

Acorn later designed their own 32-bit chip, the ARM, to try to leapfrog their competitors who were moving to the 68000 or 386, and later spun off ARM as a separate company.

37. snarfy ◴[] No.45772372[source]
Meh, performance-per-watt is not what everybody wants. I only want it in that it affords more raw performance by allowing more watts to be pumped through it without thermal overload. But if that can't actually happen then I'm still more interested in x86. Sure the lights dim when I turn my PC on, but I want the performance.
38. IshKebab ◴[] No.45772691{5}[source]
> It is like saying that Java syntax is faster than C# syntax.

Java and C# are very similar so that analogy might make sense if you were comparing e.g. RISC-V and MIPS. But ARM and x86 are very different, so it's more like saying that Go is faster than Javascript. Which... surprise surprise it is (usually)! That's despite the investment into Javascript implementation dwarfing the investment into Go.

39. throwaway173738 ◴[] No.45772735{5}[source]
It’s usually MIPI or some variant. There’s probably a way to enable the video stream but you also have to talk to the control module itself which is on a different bus.
40. jabl ◴[] No.45772750{5}[source]
The ARM server platforms seem quite decent here? But yeah, pick any small dev board and I suspect it looks quite different.
41. ◴[] No.45772886[source]
42. lambdaone ◴[] No.45772991{4}[source]
People are absolutely part of an ISA's ecosystem. The ISA is the interface between code and CPU, but the code is generally emitted by compilers, and executed in the context of runtimes and operating systems, all designed by people and ultimately dependent on their knowledge of and engagement with the ISA. And for hot code in high-performance applications, people will still be writing directly in assembler directly to the ISA.
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43. high_na_euv ◴[] No.45773546{5}[source]
ISA != ISAs ecosystem

ISA is just ISA

replies(1): >>45775876 #
44. cwizou ◴[] No.45773990[source]
According to an AMD engineer I asked at the time, when they evaluated Ryzen/K12, it was "maybe" a 15% advantage for ARM depending on scenarios.

The efficiency came solely from the frontend which is a lot heavier on x86, and stay up longer because decoding is way more complex. The execution units were the same (at least mostly, I think, might be misremembering) so once you are past the frontend there's barely any difference in power efficiency.

45. array_key_first ◴[] No.45774829{4}[source]
Intel has made SOC designs with power efficiency very, very close to M series. Look at lunar lake and compare it to what was available at the time.
46. usrusr ◴[] No.45775827{4}[source]
What AMD wants to achieve with their CPU: sell them, preferably at a nice profit. If ISA is truly not relevant for performance and efficiency characteristics, all the more reason for them to not bet on any particular ISA but spread out, to already be there wherever the buying herd goes.
47. chrystalkey ◴[] No.45775876{6}[source]
But you get the Environment for free if you choose the ISA, so ISA=>ISA ecosystem. It really does matter when making a decision
48. ◴[] No.45779448{4}[source]
49. ksec ◴[] No.45779586[source]
>Are ARM processors inherently power efficient? I doubt.

In theory yes. In practice none of the x86 design are even close, the lunar lake at same wattage barely competes with M1. And M1 is one node generation behind.

50. pezezin ◴[] No.45780610[source]
It's weird that the book is titled "PC98", because PC-98 usually refers to NEC's line of x86 but not IBM PC compatible computers: https://en.wikipedia.org/wiki/PC-98

Which I think reinforces your argument: there were non-standard x86 platforms, but thankfully they died out. Given the situation of the home computer industry during the 8 and 16-bit eras, it is a small miracle that we ended up having an open industry standard.

51. vardump ◴[] No.45780873{3}[source]
I generally agree, although one should not forget x86 (and AMD64) leaves about 3-10% performance on the table due to having a memory model that doesn't allow to reorder loads with other loads and stores with other stores.
52. hmry ◴[] No.45781279{5}[source]
> Did anyone actually use that?

AFAIK you needed to pay a license fee to write programs using Jazelle instructions (so you needed to weigh whether the speedup of Jazelle was cheaper than just buying a more powerful CPU), and the instruction set itself was also secret, requiring an NDA to get any documentation (so no open source software could use it, and no open toolchains supported it).

I remember being very disappointed when I found out about that