RFR: 8325872: Make GuaranteedSafepointInterval default 0 [v2]

[Erik Österlund]

On Wed, 17 Apr 2024 17:30:54 GMT, Coleen Phillimore <coleenp at openjdk.org> wrote:

>> This change keeps the GuaranteedSafepointInterval option for use with -XX:+HandshakeALot and -XX:+SafepointALot and removes it from working with the MonitorDeflationThread.  The MonitorDeflation thread has it's own timers and doesn't require safepoint to trigger anymore, so the GuaranteedSafepointInterval is logically unrelated except for historical reasons.
>> The option AsyncDeflationInterval default is 250 so was used anyway in this code for the monitor deflation thread timer.
>> 
>> Tested with tier1-8.  Also performance tested this which didn't show any improvements.
>
> Coleen Phillimore has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Fix argument conditionals, reran tests with SafepointALot and HandshakeALot.

Looks good!

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Marked as reviewed by eosterlund (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/18820#pullrequestreview-2007034197