RFR: JDK-8260200 G1: Remove unnecessary update in FreeRegionList::remove_starting_at [v5]

[Thomas Schatzl]

On Tue, 26 Jan 2021 12:04:02 GMT, Hamlin Li <mli at openjdk.org> wrote:

>> optimize FreeRegionList::remove_starting_at by removing unnecessary reading and setting
>> 
>> FreeRegionList::remove_starting_at(...) traverses from a node and removes subsequent N nodes from free list. But when traverses the free list, it removes nodes one by one by setting the prev and next pointers of prev and next node. it's not necessary do these settings for every node, as we can remove target nodes at once and just set prev and next pointers for just 2 nodes.
>
> Hamlin Li has updated the pull request incrementally with one additional commit since the last revision:
> 
>   JDK-8260200: G1: Remove unnecessary update in FreeRegionList::remove_starting_at

Marked as reviewed by tschatzl (Reviewer).

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PR: https://git.openjdk.java.net/jdk/pull/2181