RFR: 8257147: [TESTBUG] Set a larger default loop count for the VectorAPI jtreg tests

[Xiaohong Gong]

On Thu, 17 Dec 2020 17:46:40 GMT, Paul Sandoz <psandoz at openjdk.org> wrote:

> My suggestion for now is to just turn off tiered compilation, which gets us reasonably far, and perhaps keep pushing on compiler threshold investigation as a follow up.

OK, so I will update the patch with adding the `"-XX:-TieredCompilation"` for each test. As for the compiler threshold, I didn't have a deep investigation, but just looked at the compiler log with a simple case with it. It seems there are more uncommon-traps that might make deoptimization happen which might influences the performance a lot. Anyway, I'm not sure whether this is the main cause.

> I will follow up with our Hotspot test engineers to see if there is a way to run these tests less frequently under tiered compilation (as we do for other flags to stress the HotSpot compilers, such as `-Xcomp`).

That's great, thanks for the support!

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PR: https://git.openjdk.java.net/jdk/pull/1621