RFR: 8373026: C2 SuperWord and Vector API: vector algorithms test and benchmark [v4]

[Emanuel Peter]

On Fri, 16 Jan 2026 21:32:08 GMT, Vladimir Ivanov <vlivanov at openjdk.org> wrote:

>>>Also, it makes it harder to reproduce input dependent variance.
>> 
>> I suppose my whole goal was to eliminate input dependent variance as far as possible. Do you think it would be better to make input dependent variance measurable at the `Iteration` level? I fear that this will make the variance of the benchmark very large, and the results of a fork would be quite noisy.
>
> My personal preference is `Level.Trial`. When I work with a microbenchmark, the fewer "moving parts" it has the better. It's easy to spot fork-to-fork variance. Not so much with iteration variance where a single outlier can be caused by many factors.

@iwanowww Why is fork variance easier to spot than iteration variance?

I suppose I can try doing the setup per fork. But that does drive up the runtime of the benchmark, because you need to do warmup for each fork. But I suppose you think that is worth it?

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PR Review Comment: https://git.openjdk.org/jdk/pull/28639#discussion_r2703718518