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Comment by ucha | Hacker News Reader

They're comparing single-core perf

Indeed this is the number for single-core performance. A previous benchmark[1] showed a MacBook Air with M1 getting 1687 on the single-core test and 7433 on multi-core. Compared to a 4-month-old kitted out iMac (1251 & 9014)[2] this is 35% faster on single-core and 17% slower on multi-core (8 cores on M1, 20 cores on the i9).

Getting a better result via Rosetta 2 on the single-threaded benchmark is very impressive. I assumed that their benchmark included some vector instructions (which as far as I understand Rosetta 2 does not emulate) so this would mean that these higher numbers are for general-purpose instructions vs vector. That said, I can't find any reference to AVX or SSE in the "Geekbench 5 CPU Workloads" document, although the one for Geekbench 4 does mention them. It would be interesting to see numbers for Geekbench 4 on M1, if it runs via Rosetta at all. I would imagine that the tool is able to detect what is supported to run optimized code for each CPU being evaluated.

[1] https://www.macrumors.com/2020/11/11/m1-macbook-air-first-be...

[2] https://browser.geekbench.com/macs/imac-27-inch-retina-mid-2...

It is more than likely that Geekbench will use CPUID to establish what it is running on, and then adjust its kernels to suit the host CPU architecture. Rosetta2 would be using a CPUID that excludes the AVX and any other Intel ISA extensions that it does not support, therefore, Geekbench should be running without issues on the fastest vector extension supported, most likely SSE3 or SSE4.x.

Right, that's also my guess. What I meant was that their document describing the v4 tests[1] mentions SSE and AVX, while the v5 version[2] does not. Does it mean that the v5 tests don't cover them? I found find it surprising for a benchmarking tool but they really were mentioned before and now they're not, hence my question.

If indeed v5 tests are not particularly about specialized performance but more about real-world use cases (e.g. PDF rendering, SQLite, image compression as others have mentioned) then running Geekbench v4 on M1+Rosetta would give a comparison of emulated x86 without vector instructions versus native x86 with all of its modern capabilities. Now if the M1 wins that…

[1] https://www.geekbench.com/doc/geekbench4-cpu-workloads.pdf

[2] https://www.geekbench.com/doc/geekbench5-cpu-workloads.pdf

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