RFR: 8295158: G1: Increase card-based cost sample reporting threshold

[Albert Mingkun Yang]

On Tue, 11 Oct 2022 14:35:02 GMT, Thomas Schatzl <tschatzl at openjdk.org> wrote:

> Hi all,
> 
>   can I have reviews for this change that makes the threshold that determines whether g1 uses that sample for prediction configurable (as diagnostic option) and increases it to 1000 instead of 10 because testing has shown that that's a much better value, filtering out outliers much better.
> 
> This change is based on PR#10654, please review that one first if still open.
> 
> Testing: Testing: gha, local testing, tier1-5 with other changes in this patch series, perf testing with other changes in this patch series
> 
> Thanks,
>   Thomas

Marked as reviewed by ayang (Reviewer).

src/hotspot/share/gc/g1/g1_globals.hpp line 380:

> 378:           range(1, 256)                                                     \
> 379:                                                                             \
> 380:   product(uint, G1NumCardsCostSampleThreshold, 1000, DIAGNOSTIC,            \

Unfounded hunch: an inclusive threshold here is probably easier to reason.

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PR: https://git.openjdk.org/jdk/pull/10656