RFR: 8354228: Parallel: Set correct minimum of InitialSurvivorRatio

[Thomas Schatzl]

On Wed, 9 Apr 2025 17:33:07 GMT, Albert Mingkun Yang <ayang at openjdk.org> wrote:

> Updating the lower bound of InitialSurvivorRatio to match MinSurvivorRatio. The two removed test cases set conflicting Min and Intial SurvivorRatio, which, IMO, is an incorrect configuration, so I removed them.
> 
> Test: tier1-7

Changes requested by tschatzl (Reviewer).

src/hotspot/share/gc/shared/gc_globals.hpp line 415:

> 413:   product(uintx, InitialSurvivorRatio, 8,                                   \
> 414:           "Initial ratio of young generation/survivor space size")          \
> 415:           range(0, max_uintx)                                               \

There is code somewhere which sets InitialSurvivorRatio to 3 if it is smaller than that. It should be removed. Somewhere around `parallelArguments.cpp:108).
There is similar code next to it for `MinSurvivorRatio` which is dead code too (`MinSurvivorRatio` is already bounded with 3 at minimum).
Also, previously this value has been overridden silently, bailing out is a behavioral change that requires a CSR.

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PR Review: https://git.openjdk.org/jdk/pull/24556#pullrequestreview-2756365732
PR Review Comment: https://git.openjdk.org/jdk/pull/24556#discussion_r2037149128