RFR: 8324995: Shenandoah: Skip to full gc for humongous allocation failures [v3]

[Y. Srinivas Ramakrishna]

On Wed, 31 Jan 2024 21:50:06 GMT, William Kemper <wkemper at openjdk.org> wrote:

>> Shenandoah degenerated cycles do not compact regions. When a humongous allocation fails, it is likely due to fragmentation which is better addressed by a full gc.
>
> William Kemper has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Fix typo in comment

> If anything, the changes proposed in #17561 will reduce the likelihood that we experience a humongous alloc failure, and in the rare case that we do, will increase the likelihood that normal concurrent GC (with degen if necessary) will recover sufficient contiguous memory to satisfy the humongous allocation request.

Does it seem worthwhile then to run perf numbers with these changes along with the changes in https://github.com/openjdk/jdk/pull/17561 so as to get sharper performance numbers that include both changes (as well as each individually as you did here and in the other one). Each seems worthwhile on its own, and I am curious of the composition of the two...

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PR Comment: https://git.openjdk.org/jdk/pull/17638#issuecomment-1935046203