Initial Tenure Age

Initial Tenure Age will be a function of initial Nursery size. With
larger initial Nursery heaps, initial Tenure Age will be lower. This
helps promoting persistent objects (typically created at startup)
sooner, which reduces startup time and Nursery growth. See:
#3514

For Nursery Sizes of
256K, 512K, 1M, 2M, 4M, 8M, 16M, 32M, >=64M

initial Tenure Age is set respectively to:

9, 8, 7, 6, 5, 4, 3, 2, 1.

For OpenJ9, which starts with 2M Nursery, this will reduce the default
initial Tenure Age to 6 (from 10).

Signed-off-by: Aleksandar Micic <amicic@ca.ibm.com>

gc/base/GCExtensionsBase.hpp

@@ -1403,10 +1403,10 @@ class MM_GCExtensionsBase : public MM_BaseVirtual {
 		, scavengerScanOrdering(OMR_GC_SCAVENGER_SCANORDERING_HIERARCHICAL)
 #endif /* OMR_GC_MODRON_SCAVENGER || OMR_GC_VLHGC */
 #if defined(OMR_GC_MODRON_SCAVENGER)
-		, scvTenureRatioHigh(J9_SCV_TENURE_RATIO_HIGH)
-		, scvTenureRatioLow(J9_SCV_TENURE_RATIO_LOW)
+		, scvTenureRatioHigh(OMR_SCV_TENURE_RATIO_HIGH)
+		, scvTenureRatioLow(OMR_SCV_TENURE_RATIO_LOW)
 		, scvTenureFixedTenureAge(OBJECT_HEADER_AGE_MAX)
-		, scvTenureAdaptiveTenureAge(J9_OBJECT_HEADER_AGE_DEFAULT)
+		, scvTenureAdaptiveTenureAge(0)
 		, scvTenureStrategySurvivalThreshold(0.99)
 		, scvTenureStrategyFixed(false)
 		, scvTenureStrategyAdaptive(true)

gc/base/standard/Scavenger.cpp

@@ -409,6 +409,19 @@ MM_Scavenger::masterSetupForGC(MM_EnvironmentStandard *env)
 	scavengerStats->_tenureSpaceAllocBytesAcumulation += heapStatsTenureSpace._allocBytes;
 	scavengerStats->_semiSpaceAllocBytesAcumulation += heapStatsSemiSpace._allocBytes;
 
+	/* Check if scvTenureAdaptiveTenureAge has not been initialized or forced (by cmdline option) */
+	if (0 == _extensions->scvTenureAdaptiveTenureAge) {
+		/* With larger initial Nursery sizes, we'll reduce initial tenure age, to help promote peristant object sooner. */
+		_extensions->scvTenureAdaptiveTenureAge = OMR_OBJECT_HEADER_AGE_DEFAULT;
+
+		uintptr_t tenureAgeAdjustement = MM_Math::floorLog2(_extensions->heap->getActiveMemorySize(MEMORY_TYPE_NEW) / MINIMUM_NEW_SPACE_SIZE);
+		if (tenureAgeAdjustement < _extensions->scvTenureAdaptiveTenureAge) {
+			_extensions->scvTenureAdaptiveTenureAge -= tenureAgeAdjustement;
+		} else {
+			_extensions->scvTenureAdaptiveTenureAge = 1;
+		}
+	}
+
 	/* Record the tenure mask */
 	_tenureMask = calculateTenureMask();
 

include_core/omrgcconsts.h

@@ -464,10 +464,10 @@ typedef enum {
 #define J9VMGC_SIZECLASSES_LOG_SMALLEST 0x4
 
 /* Default object age for generational collectors */
-#define J9_OBJECT_HEADER_AGE_DEFAULT 0xA
+#define OMR_OBJECT_HEADER_AGE_DEFAULT 0x9
 
-#define J9_SCV_TENURE_RATIO_LOW 10
-#define J9_SCV_TENURE_RATIO_HIGH 30
+#define OMR_SCV_TENURE_RATIO_LOW 10
+#define OMR_SCV_TENURE_RATIO_HIGH 30
 #define OMR_SCV_REMSET_FRAGMENT_SIZE 32
 #define OMR_SCV_REMSET_SIZE 16384