Deriving G1 flag values from a latency SLO and proving they helped: what `MaxGCPauseMillis` actually controls, the young size bounds, IHOP and adaptive IHOP with an explicit safety margin, region size as the basis of every region-denominated calculation, `G1OldCSetRegionThresholdPercent` and `G1MixedGCCountTarget`, and the measure-derive-predict-validate loop. Use when GC flags were copied from another service, when `-Xms` differs from `-Xmx` in production, when mixed GC violates the SLO while young GC is healthy, when GC overhead exceeds its explicit service budget, when a full GC follows a marking cycle that finished too late, when an IHOP was set to the theoretical cei…