RFR: 8355743: G1: Collection set clearing is not recorded as part of "Free Collection Set Time"

[Thomas Schatzl]

On Wed, 14 May 2025 09:39:59 GMT, Aleksey Shipilev <shade at openjdk.org> wrote:

>> Hi all,
>> 
>>   please review this change that moves "clear_collection_set" work correctly under the "Serial Free Collection Set" phase.
>> 
>> There is probably no particular impact on timings, but just for correctness.
>> 
>> Testing: gha, gc/g1 tests
>> 
>> Thanks,
>>   Thomas
>
> Makes sense. It does not look that the amount of work done in `clear_collection_set` is trivial, so I would mark this for additional backports to improve GC logging accuracy everywhere.

Thanks @shipilev @walulyai for your reviews.

> Makes sense. It does not look that the amount of work done in clear_collection_set is trivial, so I would mark this for additional backports to improve GC logging accuracy everywhere.

My measurements showed that the actual time taken is very small, although there is some per remembered set group activity (and earlier per-region activity).

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

PR Comment: https://git.openjdk.org/jdk/pull/25222#issuecomment-2882936403