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Comment by Scaevolus | Hacker News Reader

Many CPUs have claimed to be competitive with x86, but it rarely pans out. Being able to match the IPC on a microbenchmark is good, but they often struggle with poorly tuned, low bandwidth cache and memory controllers.

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I would like to think Wei-Han Lien's (who previously led M1 at Apple) Ascalon team, as well as Jim Keller (CEO), industry veterans as they are, definitely use industry standard benchmarks, and avoid the mistake of extrapolating IPC from microbenchmarks.

But maybe I'm too optimistic?

I'll bet the publicize whatever benchmark looks most competitive to get the next funding. That's no criticism, just the way every business somewhat has to work in a competitive industry.

Given the choice between exaggerating the performance and getting funded, and not exaggerating and running out of money, I think everyone ends up choosing the former.

I'd say Apple got there with their M1 and M2 chips. But it took 10 years of incrementally improving on an already commercially viable cpu, unlike what tensortorrent is claiming.

Watt for watt, Apple's M2 demolishes anything x86 has to offer so far.

On the same line, watt for watt, pen and paper demolishes anything Apple has to offer. Now and forever.

One single, isolated metric is not the way to compare things

How much energy do you need to put into a human for it to calculate a 10 digit multiplication?

We supposedly consume about 100 watts at rest. Given that my flops are low (less than one!), I don't think I'm an efficient processor. At least for floating point operations. Producing paper and ink cartridges isn't free, either.

I might be competitive with an LLM + GPUs, but I imagine it'll demolish me on throughput.

I run inference pretty efficiently with those 100 watts.

Latest zen4 is very competitive power wise with M2, M2 still has the crown,but laptop battery life is dominated by other parts of the system when you're down to 1 to 2 W of cpu power for light workloads.

only in cinebench or other dense math workloads afaik (especially ones that don't use vector extensions on ARM).

SPEC benchmarks have M1 Max demolishing x86 in a lot of real-world applications. Similarly, in things like CFD the M2 Ultra absolutely demolishes server processors let alone laptops.

https://images.anandtech.com/graphs/graph17024/117494.png

https://images.anandtech.com/graphs/graph17024/117495.png

http://hrtapps.com/blogs/20220427/

cinebench really just tests one thing, arithmetic intensity, and it doesn't represent cache performance, branching, reordering, or anything else in a processor. but those are actually quite important to real workloads.

let's look at perf/w for, let's say gcc (chrome compiles?) or PGBench or something besides cinebench and see how the picture looks then.

Would you say x86 is held back by lack of scalable vector processing, limited to AVX512? ARM must be doing something better power efficiency and parallel processing, that x86 was too complacent in.

Those charts are at 35w for the Ryzen, so calling that a comparison with a server class processor is a stretch. I don't see the power of the M2 in those benchmarks, do you know what it was for reference?

All those charts are showing older x86 CPUs (on worse nodes), and don't contain any Zen 4 CPUs.

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