[jdk11u-dev] RFR: 8228609: G1 copy cost prediction uses used vs. actual copied bytes [v7]

[Martin Doerr]

On Fri, 8 Apr 2022 02:49:21 GMT, Yude Lin <duke at openjdk.java.net> wrote:

>> I would like to backport 8228609 which fixes a prediction error regarding cost per bytes copied.
>> 
>> The patch does not apply cleanly, so this backport is basically changing the calculation of copied bytes.
>> 
>> https://bugs.openjdk.java.net/browse/JDK-8227442 is not in 11u. So this patch also uses G1ParScanThreadState::surviving_young_words() in place of _surviving_young_words to adjust for the correct cset index.
>
> Yude Lin has updated the pull request incrementally with one additional commit since the last revision:
> 
>   remove unused variables and their dependency

Looks technically good and the fix makes sense to me. It extract the essential fix from the original change which differs a lot: https://github.com/openjdk/jdk/commit/9a4c25731eef42d18ba0c20ff3eb42f32ae90c00
An additional person with GC experience should review it.
Approvers will have to judge how relevant it is. A comment from the original author would be helpful.

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Marked as reviewed by mdoerr (Reviewer).

PR: https://git.openjdk.java.net/jdk11u-dev/pull/927