Bug 1770768 - Part 2: Add a GC parameter for the heap growth factor used when balanced heap limits are enabled r=sfink

Differential Revision: https://phabricator.services.mozilla.com/D152863

js/public/GCAPI.h

@@ -233,6 +233,16 @@ typedef enum JSGCParamKey {
    */
   JSGC_BALANCED_HEAP_LIMITS_ENABLED = 17,
 
+  /**
+   * Heap growth parameter for balanced heap limit calculation.
+   *
+   * This parameter trades off GC time for memory usage. Smaller values result
+   * in lower memory use and larger values result in less time spent collecting.
+   *
+   * Default: HeapGrowthFactor
+   */
+  JSGC_HEAP_GROWTH_FACTOR = 18,
+
   /**
    * Lower limit for collecting a zone (MB).
    *

js/src/gc/GC.cpp

@@ -1166,6 +1166,8 @@ uint32_t GCRuntime::getParameter(JSGCParamKey key, const AutoLockGC& lock) {
       return uint32_t(tunables.lowFrequencyHeapGrowth() * 100);
     case JSGC_BALANCED_HEAP_LIMITS_ENABLED:
       return uint32_t(tunables.balancedHeapLimitsEnabled());
+    case JSGC_HEAP_GROWTH_FACTOR:
+      return uint32_t(tunables.heapGrowthFactor());
     case JSGC_ALLOCATION_THRESHOLD:
       return tunables.gcZoneAllocThresholdBase() / 1024 / 1024;
     case JSGC_SMALL_HEAP_INCREMENTAL_LIMIT:

js/src/gc/GC.h

@@ -61,6 +61,7 @@ struct Cell;
     true)                                                                  \
   _("lowFrequencyHeapGrowth", JSGC_LOW_FREQUENCY_HEAP_GROWTH, true)        \
   _("balancedHeapLimitsEnabled", JSGC_BALANCED_HEAP_LIMITS_ENABLED, true)  \
+  _("heapGrowthFactor", JSGC_HEAP_GROWTH_FACTOR, true)                     \
   _("allocationThreshold", JSGC_ALLOCATION_THRESHOLD, true)                \
   _("smallHeapIncrementalLimit", JSGC_SMALL_HEAP_INCREMENTAL_LIMIT, true)  \
   _("largeHeapIncrementalLimit", JSGC_LARGE_HEAP_INCREMENTAL_LIMIT, true)  \

js/src/gc/Scheduling.cpp

@@ -56,6 +56,7 @@ GCSchedulingTunables::GCSchedulingTunables()
           TuningDefaults::HighFrequencyLargeHeapGrowth),
       lowFrequencyHeapGrowth_(TuningDefaults::LowFrequencyHeapGrowth),
       balancedHeapLimitsEnabled_(TuningDefaults::BalancedHeapLimitsEnabled),
+      heapGrowthFactor_(TuningDefaults::HeapGrowthFactor),
       nurseryFreeThresholdForIdleCollection_(
           TuningDefaults::NurseryFreeThresholdForIdleCollection),
       nurseryFreeThresholdForIdleCollectionFraction_(
@@ -148,6 +149,10 @@ bool GCSchedulingTunables::setParameter(JSGCParamKey key, uint32_t value) {
       setLowFrequencyHeapGrowth(newGrowth);
       break;
     }
+    case JSGC_HEAP_GROWTH_FACTOR: {
+      setHeapGrowthFactor(double(value));
+      break;
+    }
     case JSGC_ALLOCATION_THRESHOLD: {
       size_t threshold;
       if (!megabytesToBytes(value, &threshold)) {
@@ -314,6 +319,10 @@ void GCSchedulingTunables::setLowFrequencyHeapGrowth(double value) {
   MOZ_ASSERT(lowFrequencyHeapGrowth_ >= MinHeapGrowthFactor);
 }
 
+void GCSchedulingTunables::setHeapGrowthFactor(double value) {
+  heapGrowthFactor_ = value;
+}
+
 void GCSchedulingTunables::resetParameter(JSGCParamKey key) {
   switch (key) {
     case JSGC_MAX_BYTES:
@@ -349,6 +358,9 @@ void GCSchedulingTunables::resetParameter(JSGCParamKey key) {
     case JSGC_BALANCED_HEAP_LIMITS_ENABLED:
       balancedHeapLimitsEnabled_ = TuningDefaults::BalancedHeapLimitsEnabled;
       break;
+    case JSGC_HEAP_GROWTH_FACTOR:
+      setHeapGrowthFactor(TuningDefaults::HeapGrowthFactor);
+      break;
     case JSGC_ALLOCATION_THRESHOLD:
       gcZoneAllocThresholdBase_ = TuningDefaults::GCZoneAllocThresholdBase;
       break;

js/src/gc/Scheduling.h

@@ -387,6 +387,9 @@ static const double HighFrequencyLargeHeapGrowth = 1.5;
 /* JSGC_LOW_FREQUENCY_HEAP_GROWTH */
 static const double LowFrequencyHeapGrowth = 1.5;
 
+/* JSGC_HEAP_GROWTH_FACTOR */
+static const double HeapGrowthFactor = 40.0;
+
 /* JSGC_MIN_EMPTY_CHUNK_COUNT */
 static const uint32_t MinEmptyChunkCount = 1;
 
@@ -536,6 +539,11 @@ class GCSchedulingTunables {
    */
   MainThreadOrGCTaskData<bool> balancedHeapLimitsEnabled_;
 
+  /*
+   * JSGC_HEAP_GROWTH_FACTOR
+   */
+  MainThreadOrGCTaskData<double> heapGrowthFactor_;
+
   /*
    * JSGC_NURSERY_FREE_THRESHOLD_FOR_IDLE_COLLECTION
    * JSGC_NURSERY_FREE_THRESHOLD_FOR_IDLE_COLLECTION_FRACTION
@@ -634,6 +642,7 @@ class GCSchedulingTunables {
   }
   double lowFrequencyHeapGrowth() const { return lowFrequencyHeapGrowth_; }
   bool balancedHeapLimitsEnabled() const { return balancedHeapLimitsEnabled_; }
+  double heapGrowthFactor() const { return heapGrowthFactor_; }
   uint32_t nurseryFreeThresholdForIdleCollection() const {
     return nurseryFreeThresholdForIdleCollection_;
   }
@@ -669,6 +678,9 @@ class GCSchedulingTunables {
   void setHighFrequencySmallHeapGrowth(double value);
   void setHighFrequencyLargeHeapGrowth(double value);
   void setLowFrequencyHeapGrowth(double value);
+  void setHeapGrowthFactor(double value);
+  void setMinEmptyChunkCount(uint32_t value);
+  void setMaxEmptyChunkCount(uint32_t value);
 
   static bool megabytesToBytes(uint32_t value, size_t* bytesOut);
   static bool kilobytesToBytes(uint32_t value, size_t* bytesOut);

js/src/jit-test/tests/gc/gcparam.js

@@ -46,6 +46,7 @@ testChangeParam("highFrequencySmallHeapGrowth");
 testChangeParam("highFrequencyLargeHeapGrowth");
 testChangeParam("lowFrequencyHeapGrowth");
 testChangeParam("balancedHeapLimitsEnabled");
+testChangeParam("heapGrowthFactor");
 testChangeParam("allocationThreshold");
 testChangeParam("smallHeapIncrementalLimit");
 testChangeParam("largeHeapIncrementalLimit");