Bug 1856574 - Run GC/CC slices before page load only if GC/CC is ongoing, and increase the slice delays, r=jonco

Differential Revision: https://phabricator.services.mozilla.com/D189917

dom/base/CCGCScheduler.cpp

@@ -22,7 +22,7 @@ const TimeDuration kTimeBetweenForgetSkippableCycles =
     TimeDuration::FromSeconds(2);
 const TimeDuration kForgetSkippableSliceDuration =
     TimeDuration::FromMilliseconds(2);
-const TimeDuration kICCIntersliceDelay = TimeDuration::FromMilliseconds(64);
+const TimeDuration kICCIntersliceDelay = TimeDuration::FromMilliseconds(250);
 const TimeDuration kICCSliceBudget = TimeDuration::FromMilliseconds(3);
 const TimeDuration kIdleICCSliceBudget = TimeDuration::FromMilliseconds(2);
 const TimeDuration kMaxICCDuration = TimeDuration::FromSeconds(2);

dom/base/nsJSEnvironment.cpp

@@ -1696,7 +1696,8 @@ void nsJSContext::MaybeRunNextCollectorSlice(nsIDocShell* aDocShell,
     Maybe<TimeStamp> next = nsRefreshDriver::GetNextTickHint();
     // Try to not delay the next RefreshDriver tick, so give a reasonable
     // deadline for collectors.
-    if (next.isSome()) {
+    if (next.isSome() &&
+        (sScheduler.InIncrementalGC() || sScheduler.IsCollectingCycles())) {
       sScheduler.RunNextCollectorTimer(aReason, next.value());
     }
   }

dom/base/test/gtest/TestScheduler.cpp

@@ -265,9 +265,9 @@ void TestNonIdleCC::RunSlice(TimeStamp aCCStartTime, TimeStamp aPrevSliceEnd,
   } else if (aSliceNum == 2) {
     // We're not overrunning kMaxICCDuration, so we don't go unlimited.
     EXPECT_FALSE(budget.isUnlimited());
-    // This slice is delayed by twice the allowed amount. Slice time should be
-    // doubled.
-    EXPECT_NEAR(budget.timeBudget(), kICCSliceBudget.ToMilliseconds() * 2, 0.1);
+    // This slice is delayed, slice time should be increased.
+    EXPECT_NEAR(budget.timeBudget(),
+                MainThreadIdlePeriod::GetLongIdlePeriod() / 2, 0.1);
   } else {
     // We're not overrunning kMaxICCDuration, so we don't go unlimited.
     EXPECT_FALSE(budget.isUnlimited());

modules/libpref/init/StaticPrefList.yaml

@@ -7462,7 +7462,7 @@
 # Maximum amount of time that should elapse between incremental GC slices, in ms.
 - name: javascript.options.gc_delay.interslice
   type: uint32_t
-  value: 100
+  value: 250
   mirror: always
 
 # nsJSEnvironmentObserver observes the memory-pressure notifications and