RFR: JDK-8262068: Improve G1 Full GC by skipping compaction for regions with high survival ratio [v11]

[Hamlin Li]

On Fri, 26 Mar 2021 10:51:55 GMT, Thomas Schatzl <tschatzl at openjdk.org> wrote:

>> I'm not sure, but per code suggests in src/hotspot/share/gc/g1/heapRegionType.hpp, seems closed region should be a pinned as well. Or miss something? Would you mind to clarify this point?
>>     ArchiveMask           = 32,
>>     OpenArchiveTag        = ArchiveMask | PinnedMask,
>>     ClosedArchiveTag      = ArchiveMask | PinnedMask + 1
>
> Just because a `ClosedArchive` region is by default pinned at this time, it does not mean it will be in the future. There are no immediate plans for that, but I can think of some edge cases where it could be useful.
> 
> The correct (and intended) predicate for this check in this context is `is_pinned()`, although at the moment they have the same effect.

I see, thanks for clarifying.

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PR: https://git.openjdk.java.net/jdk/pull/2760