Integrated: 8030815: Code roots are not accounted for in region prediction

[Thomas Schatzl]

On Fri, 8 Sep 2023 10:06:10 GMT, Thomas Schatzl <tschatzl at openjdk.org> wrote:

> Hi all,
> 
>   please review this change that adds accounting of code root scan to G1.
> 
> Previously this has not been done because code root scan has been thought of being negligible in overhead. However some recent investigations showed that it can be of significant importance.
> 
> The general idea of how prediction of code roots works is the same as for the (card-based) remembered set - given statistics of cost per code roots, try to predict costs for n code roots per region.
> 
> With this change there is some reason for confusion in the naming - we use a plain `rs_` prefix for variables containing information about the card set based remembered set, and this adds `code_root_rs` (for code roots) so the meaning of the former may not be completely clear. There is the follow up [JDK-8315848](https://bugs.openjdk.org/browse/JDK-8315848) that fixes that (https://github.com/tschatzl/jdk/tree/submit/8315848-rename-rs-prefix-to-card-rs).
> 
> Testing: gha, performance testing
> 
> Thanks,
>   Thomas

This pull request has now been integrated.

Changeset: d0385712
Author:    Thomas Schatzl <tschatzl at openjdk.org>
URL:       https://git.openjdk.org/jdk/commit/d0385712130ad1073741d7861f6bee432f8d7210
Stats:     93 lines in 6 files changed: 66 ins; 0 del; 27 mod

8030815: Code roots are not accounted for in region prediction

Reviewed-by: iwalulya, ayang

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

PR: https://git.openjdk.org/jdk/pull/15632