RFR: 8270100: Fix some inaccurate GC logging

Tue Jul 13 09:47:01 UTC 2021

On Tue, 13 Jul 2021 06:16:32 GMT, Volker Simonis <simonis at openjdk.org> wrote:

> Before, the shrink factor was reset on every invocation of CardGeneration::compute_new_size(). With your proposal, it will only be reset if we expand the heap.

Indeed, my suggestion is flawed.

> "decaying" the shrink factor on every CardGeneration::compute_new_size() call makes sense.

Agree.

> so I would probably just set current_shrink_factor and _shrink_factor to 100 at the top of CardGeneration::compute_new_size if ShrinkHeapInSteps is false

Sounds good to me.

Re `NewSizeThreadIncrease`, what's the motivation for having it (used only by Serial) in the first place? Going through the git-log, I can only find the overflow-fix from JDK-8144527.

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PR: https://git.openjdk.java.net/jdk/pull/4727