RFR: 8268163: Change the order of fallback full GCs in G1

[Kim Barrett]

On Wed, 9 Jun 2021 08:45:32 GMT, Stefan Johansson <sjohanss at openjdk.org> wrote:

>> At the time of JDK-8232588 the `should_do_concurrent_full_gc()` check was preceded by a check of `policy()->force_upgrade_to_full()` that could make the full GC happen.  That seems to have disappeared.
>
> Yes, that was removed when we removed the support for old-gen och alternative memory device. I think having a bug/enhancement to investigate how to improve this is good.

The by-policy upgrade was removed by JDK-8256181: Remove Allocation of old generation on alternate memory devices functionality.

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

PR: https://git.openjdk.java.net/jdk/pull/4342