RFR: 8317755: G1: Periodic GC interval should test for the last whole heap GC [v2]

[Thomas Schatzl]

On Wed, 18 Oct 2023 14:27:26 GMT, Aleksey Shipilev <shade at openjdk.org> wrote:

>> See the description in the bug. Fortunately, we already track the last whole-heap GC. The new regression test verifies the behavior.
>> 
>> Additional testing:
>>  - [x] Linux x86_64 fastdebug `tier1 tier2 tier3`
>
> Aleksey Shipilev has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains five additional commits since the last revision:
> 
>  - Merge branch 'master' into JDK-8317755-g1-periodic-whole
>  - Optional flag
>  - Merge branch 'master' into JDK-8317755-g1-periodic-whole
>  - Keep the cast
>  - Fix

Now one can argue that it is up to the user of `G1PeriodicGCSystemLoadThreshold` to make sure there are enough idle periods... let me discuss this internally too; but my impression about the original JEP was that the idle case was the significant one where one would always use `G1PeriodicGCSystemLoadThreshold`.

-------------

PR Comment: https://git.openjdk.org/jdk/pull/16107#issuecomment-1807894609