Integrated: 8338440: Parallel: Improve fragmentation mitigation in Full GC

[Albert Mingkun Yang]

On Thu, 15 Aug 2024 06:59:35 GMT, Albert Mingkun Yang <ayang at openjdk.org> wrote:

> Extend `SplitInfo` to support more fine-grained splitting to mitigate the fragmentation issue during full GC. Added comments and diagrams in the process.
> 
> For easier review, it's best to start with `SplitInfo` and then proceed to see how it is constructed in `summarize_split_space` and consumed in `first_src_addr`. The accompanying diagrams should help create a clear mental image.
> 
> With this patch, the exec time of `runtime/ClassInitErrors/TestOutOfMemoryDuringInit.java` using Parallel drops from ~30s to ~8s, the same as other GCs, and gc-log shows similar number of GC cycles as well.
> 
> Test: tier1-8, systemgc micro bm, CacheStress, dacapo, specjbb2005, specjvm2008

This pull request has now been integrated.

Changeset: 1ff5f8d6
Author:    Albert Mingkun Yang <ayang at openjdk.org>
URL:       https://git.openjdk.org/jdk/commit/1ff5f8d65cf6153e517ee7a242d10536eee0d637
Stats:     568 lines in 2 files changed: 209 ins; 145 del; 214 mod

8338440: Parallel: Improve fragmentation mitigation in Full GC

Co-authored-by: Guoxiong Li <gli at openjdk.org>
Reviewed-by: iwalulya, zgu, gli

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PR: https://git.openjdk.org/jdk/pull/20590