Bug 1967467 - Add a GC parameter to control the nursery's max collection time target r=sfink

Differential Revision: https://phabricator.services.mozilla.com/D250397

UltraBlame original commit: 6c3309f5718e483e9c32d901e1badc237cb48037

Author: marco-c

dom/base/nsJSEnvironment.cpp

@@ -1978,6 +1978,11 @@ void nsJSContext::EnsureStatics() {
       "javascript.options.mem.nursery_eager_collection_timeout_ms",
       (void*)JSGC_NURSERY_EAGER_COLLECTION_TIMEOUT_MS);
 
+  Preferences::RegisterCallbackAndCall(
+      SetMemoryPrefChangedCallbackInt,
+      "javascript.options.mem.nursery_max_time_goal_ms",
+      (void*)JSGC_NURSERY_MAX_TIME_GOAL_MS);
+
   nsCOMPtr<nsIObserverService> obs = mozilla::services::GetObserverService();
   if (!obs) {
     MOZ_CRASH();

dom/workers/RuntimeService.cpp

@@ -375,6 +375,7 @@ void LoadJSGCMemoryOptions(const char* aPrefName, void* ) {
 #ifdef NIGHTLY_BUILD
       PREF("gc_experimental_semispace_nursery", JSGC_SEMISPACE_NURSERY_ENABLED),
 #endif
+      PREF("nursery_max_time_goal_ms", JSGC_NURSERY_MAX_TIME_GOAL_MS),
 
 
 
@@ -454,6 +455,7 @@ void LoadJSGCMemoryOptions(const char* aPrefName, void* ) {
       case JSGC_HEAP_GROWTH_FACTOR:
       case JSGC_PARALLEL_MARKING_THRESHOLD_MB:
       case JSGC_MAX_MARKING_THREADS:
+      case JSGC_NURSERY_MAX_TIME_GOAL_MS:
         UpdateCommonJSGCMemoryOption(rts, pref->fullName, pref->key);
         break;
       default:

js/public/GCAPI.h

@@ -494,6 +494,20 @@ typedef enum JSGCParamKey {
 
 
   JSGC_HIGH_FREQUENCY_MODE = 56,
+
+  
+
+
+
+
+
+
+
+
+
+
+
+  JSGC_NURSERY_MAX_TIME_GOAL_MS = 57,
 } JSGCParamKey;
 
 

js/src/gc/GC.h

@@ -76,6 +76,7 @@ class ArenaChunk;
     JSGC_NURSERY_EAGER_COLLECTION_THRESHOLD_PERCENT, true)                  \
   _("nurseryEagerCollectionTimeoutMS",                                      \
     JSGC_NURSERY_EAGER_COLLECTION_TIMEOUT_MS, true)                         \
+  _("nurseryMaxTimeGoalMS", JSGC_NURSERY_MAX_TIME_GOAL_MS, true)            \
   _("zoneAllocDelayKB", JSGC_ZONE_ALLOC_DELAY_KB, true)                     \
   _("mallocThresholdBase", JSGC_MALLOC_THRESHOLD_BASE, true)                \
   _("urgentThreshold", JSGC_URGENT_THRESHOLD_MB, true)                      \

js/src/gc/Nursery.cpp

@@ -2452,9 +2452,10 @@ size_t js::Nursery::targetSize(JS::GCOptions options, JS::GCReason reason) {
 
 
 
-  static const double MaxTimeGoalMs = 4.0;
-  if (!gc->isInPageLoad() && !js::SupportDifferentialTesting()) {
-    double timeGrowth = MaxTimeGoalMs / collectorTime.ToMilliseconds();
+  double maxTimeGoalMS = tunables().nurseryMaxTimeGoalMS().ToMilliseconds();
+  if (!gc->isInPageLoad() && maxTimeGoalMS != 0.0 &&
+      !js::SupportDifferentialTesting()) {
+    double timeGrowth = maxTimeGoalMS / collectorTime.ToMilliseconds();
     growthFactor = std::min(growthFactor, timeGrowth);
   }
 #endif

js/src/gc/Scheduling.h

@@ -500,7 +500,14 @@
    * JSGC_GENERATE_MISSING_ALLOC_SITES                                         \
    */                                                                          \
   _(JSGC_GENERATE_MISSING_ALLOC_SITES, bool, generateMissingAllocSites,        \
-    ConvertBool, NoCheck, false)
+    ConvertBool, NoCheck, false)                                               \
+                                                                               \
+  /*                                                                           \
+   * JSGC_NURSERY_MAX_TIME_GOAL_MS                                             \
+   */                                                                          \
+  _(JSGC_NURSERY_MAX_TIME_GOAL_MS, mozilla::TimeDuration,                      \
+    nurseryMaxTimeGoalMS, ConvertMillis, NoCheck,                              \
+    mozilla::TimeDuration::FromMilliseconds(4))
 
 namespace js {
 

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

@@ -60,3 +60,4 @@ testChangeParam("urgentThreshold");
 testChangeParam("helperThreadRatio");
 testChangeParam("maxHelperThreads");
 testChangeParam("semispaceNurseryEnabled");
+testChangeParam("nurseryMaxTimeGoalMS");

modules/libpref/init/all.js

@@ -1021,6 +1021,9 @@ pref("javascript.options.mem.nursery_eager_collection_threshold_percent", 25);
 
 pref("javascript.options.mem.nursery_eager_collection_timeout_ms", 5000);
 
+
+pref("javascript.options.mem.nursery_max_time_goal_ms", 4);
+
 #ifdef JS_GC_ZEAL
 pref("javascript.options.mem.gc_zeal.mode", 0);
 pref("javascript.options.mem.gc_zeal.frequency", 5000);

toolkit/components/nimbus/FeatureManifest.yaml

@@ -3708,6 +3708,12 @@ gc:
       setPref:
         branch: user
         pref: "javascript.options.mem.nursery_eager_collection_timeout_ms"
+    nursery_max_time_goal_ms:
+      description: Set the nursery's maximum time goal, in ms.
+      type: int
+      setPref:
+        branch: user
+        pref: "javascript.options.mem.nursery_max_time_goal_ms"
 
 jsParallelParsing:
   description: Pref to toggle JS parallel parsing.