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wtallistoday at 6:43 PM5 repliesview on HN

Please stop framing the multi core scaling issue as a matter of the benchmark being good or bad. Geekbench 5 scores scale better than Geekbench 6 scores because Geekbench 5's multicore test runs N independent copies of the same workload while Geekbench 6 runs one workload that has to be split across the available cores, with non-zero coordination between threads.

The Geekbench 5 approach of pretending Amdahl's Law doesn't exist is sometimes a valid benchmarking strategy, but generally is the wrong choice for benchmarking consumer workloads and devices, and that's what Geekbench is ostensibly targeting.

The fact that Geekbench 6 scores don't increase linearly with the addition of more CPU cores is not a weakness of the benchmark, it's the benchmark demonstrating an important real-world effect.

The change that Geekbench 7 makes to exclude some subtests from the multicore suite entirely will definitely have the effect of making the overall multicore score scale better with the addition of more cores, but most of the audience for those scores is going to miss out on the fact that the multicore test now measures a narrower range of tasks than the single-core test suite.


Replies

jchwtoday at 6:48 PM

Hmm, I don't fully agree. There are a whole lot of embarassingly parallel processes that people interested in many core workstations are interested in; compiling large C++ codebases for example tends to scale very well since each translation unit is independent. This is still going to not quite give you linear scaling so it's definitely still valuable to know what that looks like.

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ostitoday at 6:52 PM

I agree. For me personally I mostly only care about single thread geekbench variant, I believe it's an excellent proxy for general performance of a CPU. Multi thread geekbench (or other benchmarks) for most purposes and for most people, it's kinda useless. You just need to know that you have a quite a few cores on your computer and that it will have enough concurrency for what you do. But single thread will make whatever you do actually faster.

zamadatixtoday at 7:24 PM

It bothers me because there is no reason it can't just give 3 results: single, mixed/low thread, all core and yet there is often debate on which 2 numbers in such benchmarks instead.

But, of all of the 2-pick-only options, choosing a custom mix and calling it multi-core requires guessing your actual workload on both the content of the mixed test suite as well as the scaling profile of the CPU to reason with. On the other hand, just testing "single core" and "all core" at least only requires you to guess based on what you think the scaling profile of the CPU is.

Nothing beats just testing your actual workload, but that doesn't mean all other ways of testing have to be equally good.

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GeekyBeartoday at 8:02 PM

They do mention that the change is meant to reflect how real world programs handle various types of workloads.

> In Geekbench 7, a workload only runs in multi-threaded mode if the task it models actually runs multi-threaded in real applications. For example, the HTML5 Browser test isn’t included in the multi-threaded suite because web browsers are single-threaded (or lightly threaded).

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wmftoday at 8:51 PM

Honestly I think the world would be better off if Geekbench just refused to run on any machine over 28C. Then people could benchmark their workstations using... workstation benchmarks.