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AMD claims Arm ISA doesn't offer efficiency advantage over x86

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Re: AMD claims Arm ISA doesn't offer efficiency advantage over x86

#401

Post by a_wild_dandan »

aurareturn wrote: post #400
legacynl wrote: post #398

Earlier quoted context omitted.

Can somebody who knows about this stuff, please elaborate on if it's 'fair' in the first place to compare apple chips with amd/intel chips? AMD and Intel chips run on loads of different hardware. On the other hand Apple is fully in control of what hardware (and software) their chips are used with. I don't know, but I assume there's a whole lot of tuning and optimizations that you can do when you don't have to support…

Let's say it would hypothethically possible to put an M4 in a regular pc. Wouldn't it lose performance just by doing that? Yes. But an M4 Max running macOS running Parallels running Windows on Arm is still the fastest Windows laptop in the world: https://browser.geekbench.com/v6/cpu/compare/13494385?baseli...

That's absolutely wild. I've been loving using the 96GB of (V)RAM in my MacBook + Apple's mlx framework to run quantized AI reasoning models like glm-4.5-air. Running models with hundreds of billions of parameters (at ~14 tok/s) on my damn laptop feels like magic.

Re: AMD claims Arm ISA doesn't offer efficiency advantage over x86

#402

Post by legacynl »

aurareturn wrote: post #400
legacynl wrote: post #398

Earlier quoted context omitted.

Can somebody who knows about this stuff, please elaborate on if it's 'fair' in the first place to compare apple chips with amd/intel chips? AMD and Intel chips run on loads of different hardware. On the other hand Apple is fully in control of what hardware (and software) their chips are used with. I don't know, but I assume there's a whole lot of tuning and optimizations that you can do when you don't have to support…

Let's say it would hypothethically possible to put an M4 in a regular pc. Wouldn't it lose performance just by doing that? Yes. But an M4 Max running macOS running Parallels running Windows on Arm is still the fastest Windows laptop in the world: https://browser.geekbench.com/v6/cpu/compare/13494385?baseli...

Yeah but an AMD/Intel CPU supports many different types of configurations. Isn't it unfair to compare a chip that only supports one configuration with one that supports many?

It feels to me like we're kind of comparing speeds between a personal automobile and a long haul truck. Yes, one is faster than the other, but that's meaningless, because both have different design considerations. A long haul truck has to be able to carry load, and that makes the design different. Of course they'll still make it as fast as possible, but it's never going to be the same as a car.

Basically what I'm saying is that because it's impossible to strip away all the performance and efficiency improvements that come from apple's total control of the software and hardware stack; is it really possible to conclude that apple sillicon itself is as impressive as they make it out to be?

Re: AMD claims Arm ISA doesn't offer efficiency advantage over x86

#404

Post by magicalhippo »

VHRanger wrote: post #387
magicalhippo wrote: post #338

Earlier quoted context omitted.

Zen 5 also seems to have a bit of a underperforming memory subsystem, from what I can gather. Hardware Unboxed just did an interesting video[1] comparing gaming performance of 7600X Zen 4 and 9700X Zen 5 processors, and also the 9800X3D for reference. In some games the 9700X Zen 5 had a decent lead over the Zen 4, but in others it had exactly the same performance. But the 9800X3D would then have a massive lead over t…

I mean, huge software with a ton of quirks like a AAA video game are arguably not a good benchmark to understand hardware. They're still good benchmarks IMO because they represent a "real workload" but to understand why the 9800X3D performs this much better you'd want some metrics on CPU cache misses in the processors tested. It's often similar to hyperthreading -- on very efficient sofware you actually want to turn…

> but to understand why the 9800X3D performs this much better you'd want some metrics on CPU cache misses in the processors tested.

But as far as I can tell the 9600X and the 9800X3D are the same except for the 3D cache and a higher TDP. However they have similar peak extended power (~140W) and I don't see how the different TDP numbers explain the differences between 9600X and 7600X where the is sometimes ahead and other times identical, while the 9800X3D beats both massively regardless.

What other factors could it be besides fewer L3 cache misses that lead to 40+% better performance of the 9800X3D?

> You'd presumably also see large speedups in this case from faster RAM on the same processor.

That was precisely my point. The Zen 5 seems to have a relatively slow memory path. If the M-series has a much better memory path, then the Zen 5 is at a serious disadvantage for memory-bound workloads. Consider local CPU-run LLMs as a prime example. The M-s crushes AMD there.

I found the gaming benchmark interesting because it represented workloads that had workloads that just straddled the cache sizes, and thus showed how good the Zen 5 could be had it had a much better memory subsystem.

I'm happy to be corrected though.

Re: AMD claims Arm ISA doesn't offer efficiency advantage over x86

#405

Post by freedomben »

pezezin wrote: post #178

After playing around with some ARM hardware I have to say that I don't care whether ARM is more efficient or not as long as the boot process remains the clusterfuck that it is today. IMHO the major win of the IBM PC platform is that it standardized the boot process from the very beginning, first with the BIOS and later with UEFI, so you can grab any random ISO for any random OS and it will work. Meanwhile in the ARM…

I could not agree more. I wanted to love ARM, but after playing around with numerous different pieces of hardware, I won't touch it with a ten-foot pole anymore. The power savings is not worth the pain to me.

I hope like hell that RISC-V doesn't end up in the same boot-process toxic wasteland

Re: AMD claims Arm ISA doesn't offer efficiency advantage over x86

#406

Post by ryan-ca »

epolanski wrote: post #105
tapoxi wrote: post #84

Earlier quoted context omitted.

Since the Pentium Pro the hardware hasn't implemented the ISA, it's converted into micro ops.

Come on, you know what I meant :) If you want to support AVX e.g. you need 512bit (or 256) wide registers, you need dedicated ALUs, dedicated mask registers etc. Ice Lake has implemented SHA-specific hardware units in 2019.

I think AVX is actually power gated when unused.

Re: AMD claims Arm ISA doesn't offer efficiency advantage over x86

#407

Post by camdroidw »

newpavlov wrote: post #108
exmadscientist wrote: post #2

This is an entirely uncontroversial take among experts in the space. x86 is an old CISC-y hot mess. RISC-V is a new-school hyper-academic hot mess. Recent ARM is actually pretty good. And none of it matters, because the uncore and the fabrication details (in particular, whether things have been tuned to run full speed demon or full power sipper) completely dominate the ISA. In the past x86 didn't dominate in low powe…

>RISC-V is a new-school hyper-academic hot mess. Yeah... Previously I was a big fan of RISC-V, but after I had to dig slightly deeper into it as a software developer my enthusiasm for it has cooled down significantly. It's still great that we got a mainstream open ISA, but now I view it as a Linux of the hardware world, i.e. a great achievement, with a big number of questionable choices baked in, which unfortunately…

Reading this and child comments it would seem to me that we need a RISC Vim

Re: AMD claims Arm ISA doesn't offer efficiency advantage over x86

#408

Post by acdha »

p_ing wrote: post #393
acdha wrote: post #373

Earlier quoted context omitted.

Yes, I'm aware that Windows has memory compression, so let's think about why it's less successful and Windows systems need more memory than Macs. The Apple version has a very high-performance hardware implementation versus Microsoft's software implementation (not a slam on Microsoft, they just have to support more hardware). The Apple designers can assume a higher performance baseline memory subsystem because, again,…

Neither macOS nor Windows use a hardware-based accelerator for memory compression. It's all done in software. Linux zram uses Intel QAT but that's only available on a limited number of processors. You seem to be under the mistaken impression that Microsoft cannot gear Windows to act differently based on the installed hardware (or processor). That's quite untrue.

It was software on Intel but they presumably added instructions with the intention of using them:

https://asahilinux.org/docs/hw/cpu/apple-instructions/

> You seem to be under the mistaken impression that Microsoft cannot gear Windows to act differently based on the installed hardware (or processor).

Definitely not - my point is simply that all of these things are harder and take longer if they have to support multiple implementations and get other companies to ship quality implementations.

Re: AMD claims Arm ISA doesn't offer efficiency advantage over x86

#409

Post by bee_rider »

simonh wrote: post #354
ben-schaaf wrote: post #349

Earlier quoted context omitted.

Yes they are, but only one of those is at all affected by the choice of ISA. If modern AMD chips are better at race-to-sleep than an Apple M1 and still get worse battery life then the problem is clearly not x86-64.

Right, so as I understand it people see that x86-64 designs score poorly on a set of benchmarks and infer that it is because they are x86-64. In fact it’s because that manufacturer has made architectural choices that are not inherent to the x86-64 ISA. And that’s just hardware. MacOS gets roughly 30% better battery life on M series hardware than Asahi Linux. I’m not blaming the Asahi team, they do amazing work, they…

> So if I’m reading this right, ISA can make a difference, but it’s incremental compared to the many architectural decisions and trade offs that go into a particular design.

This is true, but only in the sense that is very rarely correct to say “Factor Y can’t possibly make a difference.”

Re: AMD claims Arm ISA doesn't offer efficiency advantage over x86

#410

Post by astrange »

p_ing wrote: post #393
acdha wrote: post #373

Earlier quoted context omitted.

Yes, I'm aware that Windows has memory compression, so let's think about why it's less successful and Windows systems need more memory than Macs. The Apple version has a very high-performance hardware implementation versus Microsoft's software implementation (not a slam on Microsoft, they just have to support more hardware). The Apple designers can assume a higher performance baseline memory subsystem because, again,…

Neither macOS nor Windows use a hardware-based accelerator for memory compression. It's all done in software. Linux zram uses Intel QAT but that's only available on a limited number of processors. You seem to be under the mistaken impression that Microsoft cannot gear Windows to act differently based on the installed hardware (or processor). That's quite untrue.

> Neither macOS nor Windows use a hardware-based accelerator for memory compression.

Not true.

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