RFR: 8342382: Implementation of JEP G1: Improve Application Throughput with a More Efficient Write-Barrier [v14]

[Albert Mingkun Yang]

On Fri, 7 Mar 2025 13:14:02 GMT, Albert Mingkun Yang <ayang at openjdk.org> wrote:

>> Thomas Schatzl has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   * iwalulya review
>>     * renaming
>>     * fix some includes, forward declaration
>
> src/hotspot/share/gc/g1/g1CardTable.hpp line 76:
> 
>> 74:     g1_card_already_scanned = 0x1,
>> 75:     g1_to_cset_card = 0x2,
>> 76:     g1_from_remset_card = 0x4
> 
> Could you outline the motivation for this more precise info? Is it for optimization or essentially for correctness?

OK, it's for better performance, not correctness. How much is the improvement? As I understand it, this more precise info is largely independent of the new barrier logic. I wonder if it makes sense to extract this out to its own ticket to better assess its impact on perf and impl complexity.

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PR Review Comment: https://git.openjdk.org/jdk/pull/23739#discussion_r1991375754